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STAT
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Bioelectrical Phenomena in the Cortex
of the Larger (Cerebral) Hemispheres.
A.I. Roitbe~k
The conditioned reflex is a central physiological phenomenon
in the normal work of the cortex of the larger hemispheres. (~*:
Hereafter referred to as the cerebral cortex.) Proceeding~fram this
;, .the main gap. in the electxopby'siological study of the cerebral cortex
can be formulated in approximately the Hollowing may; to study on
the basis o~ bioelectrical expressions of activity of cortical neurons
those~3nner nerve processes'xhieh are the basis of the coxiditioned-
reflex activity,. (Footnote: Adr~.an thinks that... "the machanism~
of the conditioned reflex cannot be determined. in terms of neuron
synapse, sad impulse! " (Adr--ion, 1938). The conditioned reflex. is a
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reflex to be realized through temcporary connection, i. e. this is a
physiological phenomenon that has definite structural foundations,
':,and certainly the mechanism of conditioned reflexes can be disclosed
by physiological methods of investigation (see Pavlov, 1932, 193t+3
Beritashvili, 1953)? ~ the other hand, in the opinion of Walter,
this is only a question of technical refinements in order to be able
to observe in the form of electrical discharges ideas that arise in
the brain of man (Walter, 1952). Of course, this notion is not
correct. Thinking cannot be expressed as adequately ideal in
bioelectrical potentials of brain tissue and cannot be reduced to them.)
Apparently the oscillographic method giving an opportunity for
direct observation of the nerve processes moat-play an incomparably
greater role than the method of extirpation and the method of
electrical stimulation, even in case it is limited~by the use of
bioelectrical phenomena as such in the objectives of investigation of
the physiological. ftmctions of the cerebral cortex, the question of
the 'essentiality of the nature of these potentials, i. e. Whether
temporarily it is not to be regarded as the physico-chemical bases
of these potentials, being put aside. Indicative of this are the
large-scale discoveries made during the last 25 years, after thg
Kell-known paper of Sanoilov (1930): in the Yield of the physiology
of the spinal cord, as Well as the quick accumulation~of~cts on
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the electrophysiology of the cerebral cortex.
Having set as ~Y purpose the use of the osaillographic method
for study of conditioned-reflex activity, .I, resolved to carry out a
whole elimina ~`~`'`'`~
P~' ry series of Investigations in conditions of p~teF~
-~~g~'iug experiments on narcotized and on normal animals and to
study bioelectrical reactions of the cerebral cortex arising during
Sts direct electrical stimulation and,.ar~ stimulation of the receptors
or the corresponding nerves. These reactions have been insufficiently
studied even in conditions of ingenious experiments, and on normal
animals they have not been able to be recorded until very recently.
As to the origin and phys~,ological iiaportance of these reactions,
tjhere have been a number of hypotheses, often contradictory.. It-is-
;,necessary~o~~thi~nk that only after solving these problems will. it be
possible to proceed to ~oscillographic~investigation of the condit3,cned-
' ' rePle~c activity of the cerebral cortex.
The work presented is experimental, and little space is assigned
' ~-1J~~ ~,~ .
to considerations not based,direotly on facts. No goal, has been-sct
-~;~
to give a systemat3.c literate survey of all that has been done in
the sphere of the electrophysiology of the cerebral cortex. Special
attention has been allotted to clarification of certain complex,
debatable questions. Although each cycle~of the investigations issued
from the preceding and the separate parts of the work have logical
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connection With one another, it is difficult for them to appear
unified under a common designation. In Part I the results are
~IAJ~A .2
presented of $e~ted experiments on narcotized animals. In Part
~II (not in this book) the results will be presented of experiments
on normal animals.
I consider it a pleasant duty to express profound thanks
to my instructor, Academy Member I.S. Beritashvili, for the
interest which he showed in my Work and for. his valuable instruction
and advice) and to Professors N.N. Dzidzishvili, A.B. Kogan, P. O.
Makarov, S.P. Narikashvili, and S.N. Khechinashvili for the valuable
critical comments made by them at reading the manuscript.
Chapter I
Certain .Data From the Flectrophysiology of'the Nervous System
Which Will be Used During Analys3,e of the Bioelectrieal Reactions
of the Cerebral Corte$
The School bf Physiology Leningrad. University, contrary to
the prevalent principle of "x11 or' nothi " has ~ a NtJQ.~I%,sfJ
n8 s Perar~ted~ various
modifications by which the state of excitation can~be expressed
(see IJkhtomskii, 1939-~+0). According to the concepts developed in
this school, excitation does not obligatorily make off in the form
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of a nave from the region of its origin. In certain conditions it
may keep to the place of origin for a acre or less long time in the
form of a fiaed~ regional excitation, ready to flare up in the form
of an eacitatiort vave~ (IIkhton~skii, 1927, 1932, 1939-~0). Yet
Chagovets (1906) for purely theoretical reasons recognized the need
Qjt;~~'
of a preliminary regional potential for the arising of spreading
excitation. Erlanger and Gasser in 1937 Mrote that the electrotonic
potential is ~7`F~fi~ue electrical phenomenon which precedes
(-at electrical #rrita~i-sn of a nerve) the current of spreading
excitation?('--' ak").
The electrotonic potential that arises at electrical irritation
of a nerve is connected, as supposed, Mith the capacitative properties
of the fibers (Erlanger and Gasser, 1937 H~B~n: 1938)? The
electrical potential quickly (after 50 microseconds) reaches a
ma$imum and is exponentially extinguished. Ta its characteristics
should be added that it grove in proportion to the intensity of the
stimulating current, that ~.t reversal of the terminals of the
stimulating current it changes~ita sign, that temperature changes
~ ~~ -
bardly affect it, and finally that it r~diates `t3.th' Zeg~i~ithmi:e-
??decrement along the nerve fibers.
The local patential of the nerve fiber Mss recorded in 19,38
by Hodgkin. He Mss unable to diacaver the local bioelectr3:ca1
potential in the nerve as a thole because of the very strong .
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polarization developed by all fibers and masking the local responses
that arise in certain fibers-at subthreshold stimulation. He
succeeded at this for isolated nerve fiber of crab. This fiber;
xhich had a diameter of 25 microns xas deprived of-the myelin sheath
that also had a positive side, since the polarization potential is
expressed more highly and radiates considerably further in medullated
fibers. The fiber was stretched xith txo pairs of forceps and placed
on three electrodes: one stimulating and txo deflecting. At gradual
intensification of the irritating stimuli (the cathode on the fiber)
the folloxing phenomena xere observed.
At very xeak stimulations only polarization arose. When the
energy of the stimulation equaled approximately 0.5 of the threshold
(for provocation of spreading excitation), then the potential
changed its character: the regular exponential curve Xas co:aplicated
by supplementary fluctuation; the potential being recorded was a
combination of ca?helectrotonus and local potential. At subtraction
of the polarization potential from this total potential, it is possible
to determine the character of the local potential: ,it quickly increases
(for a period of 0.27.mi11iseconds~~ then gradually .dies, lasting about
1.0 millisecond (Fig. l~ teatpage 6:. Local potential of nerve fiber.
Bioeleetrical'potentials are recorded that arise in the nerve fiber
{of crab) around the irritating electrode; stiniulnting is an electrical
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impulse of short duration. Recordings A and B sr3.th irritability
energy of 1.5 conditional units; A is the stimulating cathode
electrode; B is the stimulating anode electrode. Recordings C and
D are ~rJ.th an energy of 1.0; T and F are SrS.th an energy of 1.0 over
a certain time, tirith reducirion of the e$citability: E is the
irritating cathode electrodes F is the anode. G and B are With an
energy of irritability of 0.61.
In the loxer iLustration recordings E and.F are presented in
enlarged form; the cathode polarization potential is indicated by
dotted 13.ne. The a is the curv? of the local potential, obtained
after deduction of the polarization potential from the total effect
at the cathode (Hogkin~ 1938).)-
At intexu~ification of irritation the local. potential t~tas
increased and became~someWhat more prolongrd, i. e. the amplitude of
the local potential is graduated. in connection `rl.th the change of
energy of stimulation.
When the amplitude of~the local potential reached 1~-20
millivolts (i. e. 0.3 of the current amplitude of the spread3.ng
ezcitation)~ then 3,t overincreased into an ezcitation-cur_rent_,
that Sias expressed in the arising of a tMO~phase'potential (CFO-60
millivolts); the ezcitation spread along the~fiber ands passing
' `fin ~4rr.~,.
under: the i'irat deflecting electrode, reached the 'second (Fig. 1).
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The peak at first has the same course as the local potential:
the locs.l potential overincreasea into n current of spreading excitation
usually then it reaches its suaani.t, i. e. the peak arises approximately '
0.3 millisecond after the moment of stimulation. Thus, the latent
period of the excitation current (spreading) is determined by the time
that is necessary for the local potential to reach Sts ma$imvm. As
for the latent period of the local potential in response to the
electrical stimulation, it is extremely small and equals 50-80 micro-
seconds (0.05-0.08 millisecond.
The local potential spreads along the fiber for a distance
of several millimeters. It spreads further than the polarization
potential. $odgkin assumes that the mechanism of local-response
spread (regional excitation) differs substantially from the spread
of the polarization potential (the electrotonus).
? Satz xaa able to detect local potential in the fibers of whole
sciatic nerve at?frog; its duration proved equal to 0.5-0.6 millisecond
(Matz, 197) .
Castillo and Stark, (1952) on isolated motor-nerve fiber of the
sciatic nerve of frog recorded a local potential at subthreshold
electrical stimulations of the i'iber. ~,e period. of the local potential
of the' medullated fiber proved equal to Q. ~4?-0.7 millisecond; spreading
excitation aroaq at attainment by the local potential of'an amplitude
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equal to 1~~+ of the amplitude of the effective current. Excitability
fl.uctuat3 ~s {"spontaneous") Were far greater than?in the demyelinated
Fiber. According to their data, the local potential at electrical
stimulation of-isolated fiber arises in the region o~ Ranvier?'s node
and is recorded dust from Ranvier'a node and not from the~internodal
section.
Finally, local potentials ~rere detected in nQrelinated fibers
of spinal-cord roots of cat (Roaenblueth and Ramos, 1951). At
repeated subthreshold stimulations s~ith the intervals between the
stimulations equal to 0.1-0.2 millisecond. the phenomene Were detected
of the suaanation of local potentials; during certain conditions, tTith
a certain intensity of stimulation, and after a certain number of
repeated stimulations, the effective emission current arose.
? On tho basis of ~ study of the ,changes of egcitab''ility at
different poihts of ?the'nerve after applicatS.on to the nerve of a
'subthreshold shock of stimulation it tras concluded that in nerve
fibers of frog-the regional process of excitation spreads xith
decrement to a distance of up to 9 ?n~n.? from the' place of stimulation
(Zaracv, 1938;?lrudel'-OBipova, 1953)? ?
According to the data of Fudel'-Oaipova (1953), the increased
excitability in thy.nerve of -frog after appl3cntion~of subthreshold
shock of stimulation lasts 1.5-~ milliseconds. Thus; from co~parison
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of the data of Ceati7lo and Stark and of Fudel'rOsipova~? it can be
concluded that increased excitability after subthreshold shock of
stimulation lasts longer than the local potential. After the phase
~,of increased excitability there is observed ashort-term phase
(1.5-2.5 milliseconds) of reduced excitability; in addition, 8-10
milliseconds after return of the nerve. to the initial functional
state a nex period. of increased excitation is observed, '.Lis
period of increased excitability lasts ~-6 milliseconds i.e. it
is more prolonged than. the first, but, in addition to that] the
degree of excitability increase is considerably less. Tt should
be noted that the sequence changes of excitability in the nerve
that set,.in after the spreading excitation haves as known a definite
r ,~
eZectric~-1 aar~ess3on in tho fcrm of sequence potentials (~'orontsov,
1826; danger and Gasser, 1937); it is. still irapos~sible at present
to link the seq ace fluctuations of excitability, after regional
excitation of a nerve,?likewise detected by Fudel'-Osipova, xith
certain bioelectrical phenomena, since after the local potential
`~~~
in the nerve fiber no sequence' potentials t~-ere recorded. ?
Several hours after the vpers~tion of the fiber removal and
after-lengthy eaperimentativn xith its it loses the capacity to
give spreading excitation; only a local potential arises at the ,
time of any energies of stimulation, then the. Stimulation causes
only the polarization?potential (Castillo and Stark, 1952).
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also causes regional graduated excitation (Vorontsov, 1952)
suitable to i?E; direct electrical stimulation of the parabiotic part
If the excitation spreading along a nerve reaches the parabiotic
party it provokes in it regional excitation and the local potential
Slox potentiaYs. To sloK fluctuations of the bioelectrical
?2. Forms of Bioelectrical Potentials in the Central Nervous System
potential belong fluctuations of duration over 10 mf.lliseconds.
stimulation of the optic nerve and the positive or negative sign of the .
electric reaction arising~in the optic tract of the cortex at
axon. For instance, the components of the comple=~ long-term bio-
on the basis of certain electrical phenomena of the activity of the
For up to 40 years the slax fluctuations of the bioelectrical
potential in the central nervous system has been explained usually
separate components. have been treated from the point of vier of`the
arrival of the ii~ulsea along the a?tons ~ in the 'deflecting part and
the departure of the impulses along the axons from the area in question;.
the bioeleatrical potential being recorded has been considered the
different source of origin (O'Leary and Bishop, 1938)'. Attempts to
various directions that have at each given point of the cortex a very
resultant effective current of the mass of azon elements oriented..in
analyze the s1a~t biopotentiala~.deeming that they consiasted of azonic
action ow~renta emitted from the region of their arising and subordinated
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to the principle of "all or nothing", have cla~hed'K3.th insurmountable
difficulties. _
At the present time it fan be considered demonstrated that the
slag biopotentials do not consist of quick aazonic action currents but
represent a special type of activity (Renshaw, Forbes and Morison,
1940; Li Choh=Luh and Jasper, 1953) and that slow fluctuations of the
biopotential in the central nervous system are the aura-total expression
of elementary local potentials. These elementary local potentials
arise in the bodies and dendrites of the nerve cells in the region of
the synapses under the action of the ia~iulses of excitation of the
synaptie.terminals (Beritov, 1948, 1949; Bremer, 1949).
'Fhe local potential expresses a regional, local excitation
that arises 3n the neuron element under a synapse. (Footnote: Eccles
uses the terra "synaptic potential". HoKever, it should be recognized,
indeed as Beritov, ghat'once this'potent3al does not express the
excitation of the Synapse and expresses regional excitation~of the
oell,_ then it is unfitting to?designnte it a synaptic potential:
There lass remained for these potentials the desigaaation ~"local -potential",
which xill.be?used throughout the present work.) Regional excitation
and the local potential corresponding to it are charactea?istic only to
central nerve elements as spreading excitation and the, current of
action ~p~ak) corresponding to it for?the fibers of"the peripheral
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nerves in xhich, as xe have seen the regional excitation arises
only during certain conditions of experimental reaction.
?As'xas Raid, the local potential in the medullated.fibers
lasts 0.5-0.7 millisecond and in the~denq+elinated 1-2 milliseconds.
in the neurons of the spinal cord the local potentials have a
considerably longer duration. From the gray muter of the spinal
cord of cat .in the region of the posterior horn se ~
( gment iambda7)
~:.~
by needle electrode there xere?deflected, in response to threshold
stimulation of the t3.bial nerve, biopotentials the shortest duration
of Which equaled 12 milliseconds (Beritov~ Bakuradze and Roitbak,
19~+$)?. From the anterior horn of the apineil cord of cat at stimula-
tion of the corresponding motor nerve biopotentials xere deflectEd
with a duratioh of 14 milliseconds (Brooks and Eccles, 19?~$). The
greater length of the slox potentials, recorded from the posterior
horn, is probably explained not by the fact that in the cells of
the posterior horns the local potential lasts longer~th$n in the
motor neurons, but by the fact that at stimulation of the tibial
?aerve a less synchronous discharge of impulses proceeds to the cells
of ,the posterior horn t}ian to. the motor neurons in case of stimul.a-
~tion of the motor nerve containing fibers eimf.lar in conduction rate.
This probably stipulated a certain tentatioe summation of local
potentials in the cells of the posterior horns, xhich was expressed
in the fact that slox potentials were recorded of somewhat greater
duration. Mortover, Is~ccles used ?a more slender microelectrode, Which
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also should play a definite role .in the re'sult?of the experiment.
,Recently there has been success in effecting~3.ntracellular
introduction ofLthe,discharge microelectrgde into the motor neurons
of the spinal cord"(Brock, Coombs, and Eccles, 1952}. In response
to stimulation of the corresponding motor 'nerve from the motor
neuron local potentials were. discharged with a duration of 10
milliseconds.
Quick potentials. At the carrying off of biopotentis.ls from
the central nerve formationri quick potentials are also recorded.
The length of their sequence is from 4.5-1.0 millisecond, but,
when,. they floes together, nare~ proloziged fluctuations can arise ~
the complea~character of which is discovered at quick survey. Quick
potentials arise at excitation of the afferent fibers, their collaterals,
and evidently the syrsaptic terminals during excitation of the axons
of the intermediate and efferent neurons. They, also arise during
the discharge of?the cells themselves (Ecclea~ 1953; L3: and JaspBr,
1953)-. ? .The ,frequency of the: quick-. potentiaas, i. e. of` the~?impulses ?
of excitation in the axon of -the -pyramidal cell of the .cortex, can
during strychnine poisoning r~ch..500-900 per second (Adrian=and
Moruzzi, 1939)?
' Electrical potentials?_ariaing?~in the central nervoussystem
?duz~ing~ regional excitation ~and.~during :,spreading excitation of its
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neuron3.c elements are not epiphenomena devoid of physiological signifi-
cance, With regard.?to the current oP action attending the spreading
excitation, this does not require special explanations if it is assumed
that the excitation spread along the aerme fibers proceeds by means
of the current of excitation and that the transmission of the ezcitati,on
from one neuron to another neuron likexiae proceeds by means of the
excitation currents of the ayne~ptie formations (see ~Athtomskii, 1939-
~+0; Beritov, 19+8; ,calea, 196, et al. ). (Footnote: For the question
of the mechanism of transniasian of excitation, dust Holt not much can
be added to What I~3.slavskii xrote more than 50 years ago: "Finally,
it is difficult to deny the possibility of the development of any
chemical irritant at the point of contact of the terminal nerve
appaxattis With the matter subject to excitation, but at not having
any factual data it is alBO difficult, if not even more difficult, .
to prove it. ~e hypothesis of electrical action or discharge has
for itself a more tangible backing" (l[islavskii, 1895)?)
~~ To local potentials is.noM ascribed an extraordinary role in
the mechanism of the activity of theneuronic elements. ' .Of course,.
if the very important physiological ~a[portance of the,biocurrent that
arises during spreading excitation is recognized, then already a~ .
priori it is necessary to xecognize the physiological importance of
the biocurrent arising during'regiorial excitation.
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At observation of the bioeleatrical phenomena in the central
nervous system We run into tiro phenomena stipulated by the local
potentials in the neuronic elements.
When a local.potential arises in the cel3.s, then an electrotonuc
reaction arises, first in those fibers Which are aeons of the activated
neurons and secondly in those fibers Which terminate With synapses at
these neurons. The electrotonua spreads along the fibers With decrement
and during certain conditions can be detected (from the roots of the
spinal cord) at a distance of up to 10 mm. in the form of a negative
bioelectr3cal potential. Thus, the local potentials of the nerve cells
can stipulate the phenomenon of the.phyaiological electrotonua of the
nerve ,elements.
However, there Were also observed electrical phenomena of another
character that did not attract tcs themselves special attention, namely
at the arising of regional excitation in the cell from the aeon a ?
~po~itive potential xas registered; for example, at~stimulation of the
optic nerve s negative potential Was discharged from the electrode. found
in the outer geniculate body at the level of the. layer of cellular
bodies; a positive,potential.at thin tine Was discharged from.the
electrode found at the level of the axons of these cells (Bishop and
O'Leary, 19!13). Perhaps these electrical phenomena Which We sti11
?run into are phenomena essentially like secondary electrotonuc changes,
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the peri-electrons '(sic; -should be peri-electrotoni?}?(Yvedenskii,
1920}, Footnote: According to the data of Aeritov and Roitbak (195},
in the electrotonic and peri-electrotonic spheres of the nerve trunk
potentials of -opposite sign arise. For example, at comppletion of a
descending current at the cathode a ?negative potential is registered ,
that gradually weakens at removing the deflecting electrode. from the
cathode. Finally, at a certain distance it stops being registered.
Tf too the electrode is removed still further, then at completion
of the current a positive potential of considerable amplitude is
registered, and this sphere of the peri-electrotonus extends for a
considerable distance.) If this is so, then it is possible to?make
the following conclusion: local potentials arising during regional.
~ ~
excitation of nerve ce11s can stipulate electrotonic and peri-
electrotonic phenomena in neuron3.c elements. ?
Ts there the possibility.of?referring certain components, of
the biopotentials to~certain neuronic elements?
The first connection betiteen the data of oscillography and the
data of morphology was established When it was successfully discovered,
on the .basis of oscillographic a~lysis, that nerve trunks of different
d'~:~metlr produce ?at excitation bioaurrents of different length and
~r /~
that the spread. rate of these b'iocurrents (i.e. the excitations}. is
different for fibers of different size. The quick-conduction fibers
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proved to be fibers of larger diameter(the A-fiber), the s1oK-conduction
fibers mere the thin C-fibers (Erlanger and Gasser, 1937).
The establishment of a second such connection eras.possible as a
result of investigations of the b3.oelectrical potentials of the spinal
cord.
3. Some data of the Tlectrophysiolog~r of the Spinal Cord
Ca~sl discovered theft the posterior-root fibers are connected
W3.th the motor neurons of the corresponding side, first immediately
through direct collaterals and secondly through intermediate neurons
(Cabal, 1893a)* On this basis Belchterev concluded that, correspondingly,
the spinal-cord reflexes can be accomplished in a txofold Bey: the
nerve impulse can be transmitteQ directly to the motor cell of the
.anterior horn or the nerve impulse 'be "transmitted ~to~ the intermediate
neuron, Which in Sts turn directly or by means of another intermediate
neuron transmits the impul;se~to the motor neuron (Bekhterev, 1898).
At the beginning of this century it Was found that coordination
of the reflexes is realized in; the posterior half of the spinal cordt?
ithich ie very complexly organized, and that the cells. of the posterior
horns in a number of properties, for instance in sensitivity to'
strychnine, are distinguished from cells of the anterior horn (Beritov,
1910;~Bee also Pavlov, 1912-13), The fine morphology of cells of the
anterior horn and of ce11s of the posterior_horn is different: the
cells differ in size and shspe, as hell as fn distribution of synaptic
terminals on them (Cholokashvili., 1953~~.
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As a result of oscillographic investigations on cats, it ties
found. that direct effect on the motor neurons is realized through
the thickest (12-20 m~l.crons) and that the quick-conduction Yibers?
connected frith the proprioceptors of the muscles, 3. e. direct
posterior-root collaterals leading to the motor neurons, were shown
to have their origin from the proprioceptive Fibers. 2~e intermediate
neurons engage in the action under the influence of impulses from
fibers connected frith the cutaneous receptors (Lloyd, 19~+3a, 19~3b).
(Footnote: Razdol'skii in 1923+, on the basis of a comparison of-
the physiological characteristics of the tendon and cutaneous reflexes
from neurological data, came to the conclusion "that tendon reflexes
are realized by tiro-neuron reflex arcs, and that cutaneous ('reflexes
are realized) by the triple cutaneous and the po7tiyneural".)
.During, the carrying off .of biopotentials from the anterior
and posterior roots oP the spinal. cord gray-matter potenti$ls are
disclosed.(Mislavskii, 189~~), fihich are electrotonically carried out
along the root fibers (Barron and l~atthers; 193$). For observation
.of these biopotentials it ties most beneficial to place the root on
the discharge electrodes so that one discharge electrode ("active")
was # the eye thr~a-itself, but did not affect it, and the second
.~
was as far as possible from .the, brain: After Barron and Matthews
this ,method. fwe-s need by? Bonnet and Bremer (1938-195p )., Beritov and
Roitbak, (197-195(3), Yoronteov (19x1.9, 1951),, Scales {191i.6),..Roitbak
(1950), Fuortes (195?)y,~cstiuk (1955), and others.
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From the anterior roots,, i. e. from the axons of the motor
neurons slow electrotonic potentials are registered that have been
stipulated by the local potentials of the motor neurons. Apparently
the electrotonic reaction of each axon is the consequence and
expression of the local potential, namely of the cell from Which
it took its beginn3.ng.
? When the motor neurons are activated only?by escitati zr~
impulses from the direct posterior-root collaterals (for instance,
at stimulation of the muscle nerve or at threshold stimulation of
a mixed nerve or of a posterior root), then the fol7.owing electrical
effect is registered from the anterior root: a certain time after
the stimulation artefact a quiok potential arises, after.xhich a~
negative_slox potential folloxs. The initial quick~poteatial is
the consequence of ?a relatively synchronous discharge?of afferent
impulses and expresses the excitation.eurrents?of the presynaptic
fibers and of the synaptic terminals of direct posterior-root
collaterals in the anterior horn, being electrotonically carried
along ?the anterior-root fibers (Beritov, 19.6,- l~}9). The? negative
_ ,
slow potential expresses local potentials in motoneurons, arising
' belox the synapses of the?direct posterior-root collaterals.
A~large cumber of synapssea ~re?on each motoneuron of the
anterior horn. Af~te~ 100 of. them are counted one the boat' off' the
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motoneuron of the spinal cord of cat (Cholokashvili, 1953)? ~e~'
average size is 1 micron (Haggar and Barr, 1950). Apparently not
,.
devoid of physiological importance. is the fact that synapses are
arranged on the surface of the motoneuroa in the form of separate
foci that are in their nature "the synaptic fields" of the cell
(Zurabashvili, 1947)..
Excitation of one synapse is insufficient to arouse the cell
and to be discharged to its axon. It is likexise assumed that
insufficient for this is ezcitation of several synapses that remain
far from one another (Larente de Nb, 1938). Excitation of a
motoneuron and discharge to the axon proceed When afferent impulses
come simultaneously to a Mhole group of synapses arranged on the
body of the cell in a certain prozim3.ty to one another. Otherwise,
only regional_eacitation arises in-the cell, With a local potential
corresponding to it; as 'occurs in a nerve.fiber at subthreshold
stimulation (Fig. 2,~tertpage l3: Local .potentials of motoneurons
of the spinal cord of cat. _ A: A microelectrode is,.introc'iuced into
the anterior.horx~ in the region of a group of motoneurons of the
quadriceps muscle. A slow negative potential, 100 microvolts, 10
ntil.liseeonda (Brooks and Eccles, 1948), is registered in response to
a shock of atimu3.ation applied to the quadriceps nerve. B: Potentials
from the 8th anterior root in responds to a~"shock of stimulation to
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the 8th posterior root. The upper-curve is recorded on non-
narcotixed animal. The second and third curves are recorded after
giving'n~mbutal, 70 and 90 mg. (per kg. of weight), respectively.
C (IPA: B looks like a beta in Russian; the 3d letter of the alphabet,
~ ~ ~~~
which Z here ,call C,. looks like a capital B): The same carryir.{~g
off; non-narcotized animal; the gastrocnemius nerve is stimulated.
The upper curve is the discharge of motoneurons, which arose 0.2
millisec. from the beginning of the development of the local potential.
The lower curve is the affect of the same dti.mulation, but at the
time of a state of inhibition of the motoneurons caused by the
preceding stimulation: only a local potential arises (Eccles, 1946).
For all illustrations stimulation artefact proceeds at first, then'
r ?
~fluctua~ion .stipulated liy arrival of afferent impulses proceeds at
first; after this fluctuation the local potential arises (in pure
form or complicated by the excitation current of 'the inotoneurons) .. )
Thus, the arising of the discharge of the neuron assumes seizure by
the excitation of a certain territory of the cell body, as for the
arising of spreading excitation in a nerve fiber, seizure by regional
excitation of a cextain length of the fiber is required (Rushton,
19373 Dfakarov, 1947.) ., .
In experiments with intracellular discharge of potentials of
the motoneurona it?was ascertained that the discharge of the m,otoneuron
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proceeds at attainment of a critical amplitude of 10-7..2 millivolts (1~10-
of the amplitude of the peak potential of the motoneuron) by the local
potential. It was concluded that at excitation of a synaptic terminal
a local potential? arises 1 millivolt in magnitude; thus for a discharge
of the motoneuron to'have set ini simultaneous stimulation of a
\T
minimum of 10 ayu+aptic terminals is required (Eccles 1953)?
A negative slow potential begins xithout an appreciable latent
period after the initial quick f luctuation~ usual;Ly still in the
descending limb of the latter (fox cat it begins 0.7 millisecond
after the moment of the arising of a quick fluctuation). Hence, it
is possible to conclude that the 1oca1 potential 'of the cell arises
under the action of a biocurrent of the synaptic terminals with a
negligible latent period,-as in the nerve fiber in response to its
direct electrical stimulations i.e. with the latent period measured
by fractions of a millisecond. This fact must serve as one of the,
arguments in favor of the electrical theory of the transmission of
an excitation from neuron to neuron.
The discharge of the motoneuron proceeds at the attainment of
a certain critical magnitude by the local.potential~ i,e. by regional'
excitation. The delay in the conduction of the excitation is Stipulated
by th3,s circumstance and is determined?by?the time (2 milliseconds
and mAre) which passea?xhile the local potential that has arisen reaches
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this critical magnitude (Eccles, 1946). Thus,~there is essentially
the same phenomenon as in the nerve fiber, but different time relation-
ships.
As has been said; duration of the local potential in. the cells
of the spinal cord of cat equals 10 milliseconds. A biopotential of
greater length, of the order of 15 milliseconds (the rising phase
lasts 2.5 milliseconds), is discharged Prom the anterior root. This
is explained by the fact that at electrotonic "spread" of the cellular
potentials the duration of the. potential is increased, its form is
somaWhat distorted (Eccles 1946), and its angnitude is sharply reduced.
When the motoneurons are stimulated, this is expressed
oscillographically in this, that the slox potential is broken and a
quick biocurrent of great amplitude arises (Fig. 2). The slox potential
at the time of th,e disahar,~e of the motonau~-^ons can only ~~aken. 'u"`~is
needs to be understood as an expression of'the fact that excitation
of only part of the activated matoneurons has proceeded. In those
xhich xere not stimulated, local?potentiala continue to develop and
then to die. out. However, excitation of the motor axons can proceed?
eTen xithout the corresponding cells having been discharged: the
?Pibere can.be excited under the stimulating ix~.t'luence of currents
stipulated by local cellular potentials. In this case the excitation
impulses of the motor e=ons arise and.praceed an the background-of a
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slox potential (Beritov and aoitbe~lc, 1947b), The anterior-root
aaonic excitation currents in this case too arise at attainment
of a certain magnitude b9 the slaw potentials and disappear., in
connection ~t3.th prolonged stimulation, `-hen the aloM potentials
xeaken to a certain magnitude. Thus, the setting in of the anterior-
root excitation currents depends strictly on the size of the slot
potentials (Beritov and Roitbak, 1954).
In the anterior roots of the cervical portion, from which
the diaphragm nerve proceeds, in connection xith each respiratory
cycle there arise a slow negative potential (electrotonic reaction)
and a group of quick (potentials). The latter 'Mithout decrement
spread along the fibers of the?diaphragm nerve, The s1oR negative
potential arises according to the plisse of 3.nspiration and diminishes
?.
:~
at?the time of the expiration phase. Quick .potentials arise mainly?
on the ascending limb of the slox potential. They are lacking at
time of the, expiration phase (.Gesell, Hunter, and ?I;illie, 1949). .
Thus, under the influence of impulsatton (sic: ~impulss excitation?)
from the respiratory center?there arises in the-?motoueurons essentially
the same bioelectrical reaction as under the influence of the afferent
impulses. Intensified respixatory navementa are associated xith
intensified~slorr potentials snd intensified discharges?.of impulses
and, contrari~riset at weakening of the respiraticn axing to previous
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artificial hyperventilation, both components of the bioelectrical
reaction Weaken. Thus intensity of discharges arising periodically
in the diaphragm nerve under the influence of~the "impul.sation" of
the 'respiratory center proves dependent to a certain extent on the'
intensity of the slox negative potentials discharged Prom the
corresponding anterior roots.
It t+e.s Well knrnrn, even at the time of 8echenov, that if a
subthreshold stimulation of certain intensity, i. e. a stimu]-ation
which does not cause reflez contraction of muacles~ is applied to
a sensory nerve, then it remains xithout effect on the reflex center.
Tn experiments on cat, if xithin 10-1j mi1,13seconds after the .first
subthreshold shock oY stimulation a second analogous stimulation is
applied, -then 3t Dann cause a ~ reflex (flreed and crntoxkera, i932~} . ? ~.'he
curve of .sui~tion~ is identical, in form and in time relationshipa,~
to the slob potentials discharged during these condit3.ons,of stimulation
frost the anterior root (I,lo~d, 191l~6). (Footnotes According to Scales'
ezperimante I(19~+6), the aunm~tion curve in regard to provocation of
the discharge Qf the motoneurons continues 10 milliseeonds~ i~.e.,it
continues'for as long..a time as the local potential 1,asts spontaneously
.in the motoneuron (see also Soatiuk, 1953}.) Consequently, at applica-
Lion to one and the dame sensory nerve of txo excitation discharges
xith ths~ interval such t2m-t the second .discharge of impulses reaches
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the motoneurons in the period of the regional excitation beginning
in them, response to the second discharge is facilitated. Thus,
phenomena of facilitation and sum=oation. Zt has a direct relation-
ship with the mechanism of the arising of excitation impulses. As
in the nerve fiber too, local. potentials here are "forerunners" of
spreading excitation current. Oecillographic investigations have
revealed the accuracy of the theoretical conditions, according to
Which there arises in the nerve cells regional excitation, Which
can be finely graduated according to incoming impulses and Which
can flare up in the form of an excitation wave (iAshtomskii, 1927;,
1932, 1939-~0}? On the other hand, the concept of the regional
state of the central .excitation, created by Sherrington and~his
regional excitation of motoneurons has a relationship with the
sc}iool,~has received confirmation. As known, according to this
concept the central state of~excitation"arising in the motoneuron
under the influence of the discharge of the stimulating .afferent
impulses grows over a .period of several sigmas '(3'!ts ? thousandths
of a second.}~ reaches a maximums and, gradually xeakens further,
rlasting generally about 20 sigmas. The discharge of the motoneuron~
proceeds then when the state of the central excitation reaches a'
certain threshold magnitude; the ao-called. synaptic delay is the
time Mhich,ia necessary for. the central state of excitation to have
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-28-
reached this threshold magnitude {Creed and coxorkers, 1932). As
we see, all phenomena Which are Pound issuing from the hypothetical
idea of the central state oi' ezcitation are ezplained on the basis
of this xhich rtes clarified by direct study of'the local potentials.
A long (about 100 milliseconds) positive sequence potential
is recorded after a slox anterior-root potential, even if it (the
latter) is not con~licated by quick potentials or by supplementary
negative fluctuations. At the time of this sequence potential a
reduction is observed of the excitability of the corresponding
motoneurons ~ (Brooks, Daftn~n and Fccles, 1950). Thud long., resultant
positive potentials arise after regional excitation of neurons and
are associated vita the reduction of their aacitation.
.At intensification of the stimulation of the nerve from the
anterior root double bioelectric effects are discharged (Fig. 3):
after the ,negative potential (or, discharge) already considered, a
second s1o~ negative potential (or discharge) follo~`s. (Legend
to Fig; 3, teat~age~17: ~e biopotentials of motor neurone of the
spinal cord of cat, tthieh.first arise under the influence of 3.mpulses,
from the direct posterior-root collaterals and then under the
influence of impulses i'raaL th,~ intermediate neurons. The potentials
are recorded of the anterior root of the spinal cord of "decerebrattd
cat, that arise in reecponee to separate stimulations of the cutaneous
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nerve of the. corresponding side. A - xeak stinnalation. B -strong
stimulation ~Brooka and Fuortes~ 19`j2).) These data xere confirmed
by experiments xith intracellular discharge of potentials of the
motor neuron: .a second ne~gntive fluctuation arose at a certain force
of stimulation of~the sensory nerve. At'intensification of the
stimulation the latent period of its arising Mss shortened (Eccles
1953}. The duration and amplitude of the second elox fluctuation
xere very chsnged. It xea established. that the second fluctuation
xas connected xith the activity of the intermediate neurons and
expresses regional excitation of the nator neurons arising under
the effect of impulses of excitation from aaona of intermediate
neurons. Impulses from intermediate neurons fail to be registered
from the anterior root because of their asynchronous admission.
TYiis second negative fluctuation, Mhich can be complicated by
especially poxerful and frequent biocurrents.of the anterior-root.
fibers, is cha'ra.cterized by the 'fol3ox}.ng propertia"s: 1) it arises.
only during good functional'stdte of the praparatiori; 2} it arises
in connection xith intensification, as xe11 a~a in ,connection xith '
repetitions of the stimuli; it groxa at .repeated stimulations; 3)
during prolonged, stimulation this Fluctuation primarily weakens,
i. e. this effect is subject to quick eihaustion;; ~) this fluctuation
and the discharges corresponding to it arb eztraord.inarily intensified
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under the effect of strychnine, Whereas the first negative fluctuation
is not significantly Intensified. All` these peculiarities are
{~ The
characteristic_to the iritermedlata neurons (Bez'i-tov, 198).
quick ea~austion of the intermediate neurons as compared xith 'the
motor perhaps is dependent on the fact that the fist are distinguished
by their compara.tivel.y small size, i.e. they contain a relatively
small, amount of protoplasm (lialon, 1932). There are facts indicative
that nerve elements which contain a larger amount of the system being
excited are exhausted later (Berltov, 1932)?)
When the functional state of the spinal cord is poor and When
any intensity and frequency ('up to 5a a second) of stimulation is used,
only short-term aloW fluctuations are recorded, expressing regional
excitation that arises undex the effect of impulses from direct
osterior-root collaterals (Beritov and ~bitbak, lg~7b; Eccles, 19t+6)??
. p
Tn the intermediate neurons at this t3.me under the influence 'of the
afferent impulses there also arias only a regional excitation, local ?
potentials Which can ~ defeated at discharge of potent~la from the .
posterior roots. ?
At discY~e-rge of pot?entlals from the posterior roots, tiro
incidents are distinguished': disaharga from in't'act root and from
the central end of sectioned root. In the first case at stimulation
of .the corresponding nerve at first a quick bioelectrlcal-component
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is registered,~connected xith the afferent impulses that proceed
along the root in question; after it folloxs a slaw potenti+~l
connected with activation of the gray matter of the posterior half
of the cerebrum. Tlie initial quick component of the?bioelectrical
reaction vas conf'iznned by a special study of Beritov and Roitbak
(~,91{?7a) and then by Lloyd (1949). It proved very complex in
character: to the biocurrenta of the at~erent impulses proceeding
under a pair of discharging elect~odea is added a series of quick
biopotentials; it vas found that the latter are carried out from
~~~
the ~e~rebrum?and discharge the ezcitation biocurrents of the
collaterals of the afferent fibers and of their synaptic terminals
(Beritov and Roitbak, 1947x). %? f~
It is known that the slaw potential discharged from the
posterior root is an electrotonic reaction i-hich arises as the
xesult of arrival in the spinal cord of .a discharge of afferent
in~pulsest slox potentials identical in character being registered.
both from the root along xhich these potentials reached the braiin
and from adjacent roots. Since the xork bt' $ccles and Malcolm,
(1946 and Beritov and Roitbak (1947-1950} it has been possible
to consider moat probable that the slow posterior root potential
arises because of activation of. the neurons at xhich.ths fibers of
the stimulated root terminate. (In th,e opinion of certain investigators
?
?{Barron and MQ-tthexs, 1938; Lloyds 1949; and Yorontaov, 1955} slox
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of potentials, to the arising of an electrical current, and to electro~.tonus
posterior-root potentials discharge the.e=citation of the presynaptic
fibers and~or synaptic terminals. !'or~criticiam of this idea see
Eccles (1950).) Activation of the neurons, the arising oaf regional
excitation (of local potentials) in them, stipulates electrotonic
reaction of the posterior-root fibers. When under the action of
afferent impulses in the body or in the dendrite of a given neuron
a local potential arises, this leads to the establishment of a variety
the bra3n,'the slow potential, discharged from the root, expresses local
potentials arising in the .intermediate neurons of the posterior half of
root potentials are a composite expression of a groat number of local
this and in that Which Was not in an active state. Thus, 81oW poeterior-
electrotonic reaction arises both in. the fiber Mhich Was excited before
in those fibers Which terminate With synapses at the neuron in question;
potent3.sls namely of those elements at Which the fibers of the root in
question terminate.
Thus; tits can fudge indirectly about the.exaitation of the
intermediate neurons and about the impulses proceeding from them,
through the anterior-root effects (supplementary negative fluctuation,
supplementary discharge). We coin 3udge concerning, regional excitation
of intermediate neurons directly on the basis of poaterior~root slow
potentials.
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figs. CFO-~2~
,Through the works of Bexitov and Roitbak (19~s
it is knoxn that, to 1~egin t~rith, from the anterior roots poWer~ul
sterior
slow potentials can be discharged and at this time from the Po
there are 'virtually no bioelectrical reactions. It is possible to
The azous
observe this at stimulation of the humeral nerve in f`r'og. 1
of the intermediate neurons of the humAral region of the spina
cord Which axe thereby being ezcited, termin~e-te in 'the lumbar region
directly on elements of the anterior horns. In the second place,
from the posterior roots slrnr potentials can be registered of very
eat amplitude and leagth, and at this time from the anterior roots
6r
only Weak, short-term Potentials can be registered arising under
the effect o~ impulses from the direct posterior-root colt&'terale.
stimulations a[the sensory nerve When
This is observed during strong
~ional state of the preparation is poor. ,On the basis'of~
the funet
these facts, ss Well as on the basis of lack o~ parallelism in.rega~d
otentials of the posterior
to the intensity and temporal course of the p
roots it Was concluded that 'the souses' of their origin
and anterior
xere different. (yater Fuortes (1951) disclosed similar fact's and ..
came to an analogous conclusion. H~rever~ these facts ind3.cate that
cerebral biocurrentd do not spread diffusely along the spinal cord
and that'Nithin the brain eleatrotonic d3.stributlon too of biocurrents
along the fibers is possible only for relatively small distances:
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-3~-
This latter conclusion requires explanations. That electrotonic ,
distribution of the currents ti-ithin the brain is possible for short
distances demonstrates the fact of the arising of an electrotonic
reaction art the anterior and posterior roots: yell them the
anterior- and the posterior-root fibers proceed a certain distance.
~Sthin the brain from th,e cells to the exit from the brain (or,
contrarixise, from the entry into the brain to the place of
termination at the cells). The faet~that the slox potentials
discharged from the anterior root at stimulation of the humeral
nerve are not registered from the correspond3.ng posterior one shows
that Within the brain along the direct posterior-root collaterals
(Which terminate on the motor neurons) electrotonic spread of the
potentials occurs t~ith such decrement that they do not reach the
puce of entry Of the posterior-root fibers into the b'ra~?= 4s
said poxerful~slow posterior-root potentials. do riot register from
. the anterior roots. This shrnts that the eleotro:~onus cannot spread
along the aaonB oi' the ,intermediate neurons ?because,? otherwise, it
Mould be ..detected in the anterior roots (as the afferent impulse
is detected that arrives at the motor neurons through direct collaterals
Apparently a biopotential arising in the nerve cell cazi be
detected ozil.y at a slight distance from it. Supportive of this concept
too is the fact that the amplitude of the local potential of the motor
.?
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neuron at intracellular discharge equals 10 millivolts and at extra-
cellular discharge from.the nucleus of motor neurons 100 microvolts
(Fig. 2,A), i. e. in a 100 times lesser tmgnitude.
~. Concerning Long Nonfluctuating Bioelectriaal.Potentials
As far back as in early inveatigAtions of the bioelectrical
phenomena of the central nervous system, carried out with the aid
of a galvanometer, similar potentials were reported. Mislavskii
(189, 1900, at the discharging of current from the posterior
roots of the spinal cord of frog observed long nonfluctuating
biocurrents during tetanic irritation of the sciatic nerve and
at adequate stimulations of the skin.
Delon and Lapitski3, recorded during discharge of currents
from the spinal cord (1 electrode on the surface of the lumbar part,
of the spinal cord, 2 on a crossHise section) the following phenomena:
quick fluctuations fo7loXing the rhythm of stimulation of the sciatic
nerve up to l00 per second, were placed on a background of a slow
nonfluctuating potential, the amplitude of Which i.*as increased with
increase of frequency of stimulation up to 7,00 a second and reached
1 millivolt (Delon and.Lapitakii, 1935). In Fig. ~,.D is. presented
the oscillographic recording of a nonfluctuating biopotential,
registered from the posterior root during tetanic stimulation of the
sciatic nerve.
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(Legend to Tig. ~~ teztpage 20: bong nonfluctuating potentials
generated by neurone of the posterior half of the spinal cord during
tetanic stimulation of the sensory nerves. Curarized frog With sp~l
cord revealed and circulation undisturbed. L2'C. potentials are
dischn,r~ed from the 9~h~posterior root at a distance of 1
G:,,J ~~~~ ~~t mm. from
the brain. Direct-current booster. Recording by atring~_
oscillograph. A -the trifaci
l
a
nerve of the opposite side is
stimulated; frequency of stimulation 10 per second. B -frequency
of stimulation 100 per second. C -the sciatic nerve of the corresponding
side is stimulated; frequency of stimulation 10 per second; the beginning
and end of brief stimulation. D - ~equency of stimulation 100 per
second; beginning and end of brief stimulation. Time marks for 10
milliseconds. (Roitbak, 1950).)
During tetanic irritations of the sensory Nerves or of the .,
posterior roots as Well as during adequate stimulations, for instance,
of the musaie receptors a long nonfluctuating potential is registered
from the anterior roots' (Barran and Matthe~rs, 1938). .
In ~'ig. 5 aye
presented recordings of the bioelectrical reaction of the ~anter3.or _
stimulation of the sciatic nerve. As assn, a nonfluctuating potential
arises on the background of Which the 2'luctuatiows'are arranged- .
according to the rhythm of the stimulation. At cessation of~stimuZ,ation
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the potential gradually Weakens, but even after 4 seconds does not
reach the abscissa. It is certainly susta3.ned by'"impuleation" from
the intermediate neurons. There is aftereffect too in~regard to
quick fluctuations (Beritov, Kvavilashvili; and Roitbak, 1950).
An analogous recording Was made by Fuortes (1951).
Thus the central nerve elements at? arrival of frequent
impulses of excitation to them generate long nonfluctuating potentials
that certainly reflect the noniluctuating state of the regional
excitation.
(Legend to Fig. 5, teztpnge 21: Prolonged nonfluctuating
potential generated by motoneurons of the spinal cord. Spinal
strychninized preparation of frog. 10'C. Potentials are discharged
. .c_~
from the 9th anterior root at a distance of 3 mm.. from the grain.
slaw potentials. At a stinwlat3.on?frequency of 10-100 per second
from the posterior roots of the apj.nal cord are reeoi-ded considerable
Constant-current booster. Recording by string oscillograph. The
sciatic nerve of the corresponding side is stimulated;-frequency of
stimulation ~0 per Second. A -beginning of stimulation. B -end
of stimulation and aftereffect. C -length of aftereffect 1 second
after recording o~ B. .Recording of D Was made 3 seconds after"C
(Beritov~ Svavilashvili and Roitbak, 1950).)
At stimulation of'the branch of the trifaacial nerve 3n frog
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the potential acquires a nonfluctuating character (Fig. ~+, A and B).
Thus, excitation imnulse.s comae from the cerebrum to the spinal inter-
mediate neurons in the cord, because of xhich an electrotonic reaction
arises in those fibers of the posterior root that form a synapse w3.th
these neurons. Stimulation of the trifacial nerve usually does not
cause considerable bioelectrical reaction of the anterior root even
after strychnine poisoning of the spinal cord xhen stimulation of
the peroneal nerve causes most intense convulsive anterior-root
discharges (Roitbak, 1950). It would be possible to think that
impulses proceeding along the descending courses at stimulation of
the trifacial nerve are subthreshold for the intermediate neurons,
for instance, because of the fact that the corresponding synapses
are placed at a greater distance from one another. But then summation
phenomena xould be.eapected at~a combination of stimulations. of the
trigeminal nerve and of the peroneal nerve. On the contrary, it
appears: if the peroneal nerve is stimulated on a background~of
tetanic stimulation of the trigeminal nerve, causing a nonfluctuating
posterior ,root potential, then the reflex from stimal.ation of the
peroneal nerve proves del"eyed. Thus stimulation of the tritacial
nerves causing a sla+~ potential in the character of a single bio-
electrical reaction in the spinal cord: generated by the neurons oP
the posterior half of the-"spinal cord, stipulates inhibition of the
..
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reflex activity of the spinal cord (Roitbak, 1950 .
? The concept of the cauisal connection of the p~ntral inhibition
rith the slox bioelegtrical p6tentiala has been expressecl?by a number
oP physiologists (see,Beritov,_ l~?8). However, it is interesting
that it is possible to reach this conclusion on the basis of the
~?~ obtained by Sechenov (1882) Sechenov in his outstanding
investigation of electrical phenomena in the medulla oblongata
ascertained that teianization of sensory nerves leads to inhibition
of "spontaneous" discharges in the medulla, oblongata Rye folloring
:from the phenomena described by him deserves special attention.
Tetanic stimulation oP a nerve leads to "deviation of the magnet, so
that it remains diverted to the negative side even during further _ ~~
tetania8tion", i. e. in the medulla oblo ~ a ~~?
? ngata~a nonfluctu~ting potential
arises and inhibition thereby occurs of the "e
pontaneous" discharges.,
~In this Work of Sechenov, devoted~to the study of inhibition on the
basis of galvanic phenomena, We first find indication of the connection
be?txeen the inhibition and the 'nonfluctuating long bioelectrical
potential, to xhich rione?of his comaentatora has tarried his attention.
Tn eaperimcnts r'ith intracellular discharge oP biopotentials
of motoneurons it t~s established that rhea inhibition of afferent`
impulses comes, to a motctneuron, then a positive potential is re stared.
8~-
Prom its body (Brock and c?'aorkers,. X952;. Eccles; Zg52, 1g53~. .(Footnote:
See Roitbak, 1955, Kogtiuk, 1955,,? and. l~otanpi,-1955s on the question of
.the electrical phenomena oP?the inhibition proceas.)~
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Thus, during analysis of the bioelectrical potentials of the
spinal cord it proved possible to eaple~in the~.r physiological
importance and to ],ink certain components of these potentiate x3.th
the activity of certain morphological formations. For instance,
we sax 3 components of the anterior-root potentials successfully
referred to the activity of the posterior-root collaterals, molar
neurons, and intermediate neurons.
It is an incomparably more complex matter than the inter-
pretation of the bioelectrical potentials of the cerebral cortex
at an attempt to refer these or other components of the bioelectrical
reactions of the cortex to the activity of certain neuronic elements
of the cortex, of that portion of the central nervous system xhich
..,
is most c~~plea in organization. Hoxever, only by proceeding in such
a Way can the origin and importance be ezpldined of the bioelectriaal
reactions of the .cortex and: likexise, can the electrographic method
be'used for study of the physiological processes and phenomena of
the cortex. bn the other hand.,. ~t~ solving 'thin problem, it also
becomes possible to refer these very processes end phenomena to
,=
certain morphological bases.and then, to use Pavlov's expression,`
the dynamic. phenomena that break out in the Cortez can 1~e coordinated
to the vary firbe~details of the construction of the apparatus (Pavlov,
1932). It is impossible not to agree xith Pavlov in this, 'that
during a study of the oortical activity only those concepts xhich
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are characterized as spatial concepts have likelihood of mastering
the subject.{Pavlov, 1912, 191~~.
Chapter IZ
Bioelectrical Potentials Arising in the Cerebral Cortex During
Direct Electrical Stimulation of its surface
The cerebrum differs fxom the spinal cord by, among other things,
the fact {and this has drain the attention already of the first investi-
gators of the electrical phenomena of the central nervous system) that
during the absence of special stimulations and during deliberate
exclusion of ezternal atimulationa from the cerebrum and from the
cerebral cortex, in particular, certain electrical fluctuations are
discharged. E~.dently 'die so-ca11.e$ "spontaneous" electrical activity
of the cerebrum, is a..consequence and an expression of the greater
excitability of its nerve elements, in: comparison xith the spinal
neurons. Apparently various negligible external and internal st3.mula-
tions are capable of causing ezcitation of the neurons that compose
the nerve centers of the cerebrum. This should particularly be
referred to cortical neurons possessing highest excitability. We
s'nall come back to'this question again..
As for the speeiall.y provoked bioeleet~ical reactions of the
. ?-
cerebral cortex, this question too comprises the main content of the
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present investigation. The folloiring are ,experimental possibilities
' for excitation of the cortical neurone by means of nerve impulses
the source of Which can be determined. .
a) Excitation of afferent systems of the cortex by ade uate
q
' stimulations of the receptors or by electrical stimulation of the
corresponding sensory neryea.
b) Excitation of the system of calloaal fibers by electrical
stimulation of the cez'tex of the opposite hemisphere or of the corpus
calloaum itself. It should be noted that Dnnilevekii wss the first
to observe bioelectrical reactions in the cortex at stimulation of
the cortex of the opposite hemisphere (1891). ~Q/Yt ~.Q,.~``J~~
c) Excitation of the ayatem of 2'ibers ~in layer I of the cortex
. by direct electrical stimulation of the surface of the cortex.'
. ~ ?d') FinaLty, tt is possible "to send antidromically`eacita~tion
impulses into the pyramidal, neurons of the cartes during stimulation
of?the pyramidal tracts (Woolsey and Chang, 197). .
The first tWO poea.ibilities'xere used during a study of electrical
? phenomena in the eortez even in the la$t century az~d at the.beg~ing
of this century. With the development of an oacillographic technique
quite a .large mamber of similar investigations apQoared (see Cha ter
.p IV}~
In xorld literature until recently there ~+ere only ?2 ai"ticles
relative to 'the bioelectrical reactiona~of the cerebral cortex that set
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in at the time of c'lirect electrical stimulation of its surface. The
,first such investigation xas made by Adrian (1936). Some additional
facts Were reported in Rosenblueth and Cennon's xork (192}~ In'
1950 I presented a paper at a "session of the Georgian Physiological
Society on a method I had xorked out for~the set-up of such experiments
and on the characteristics and. source of cortical bioelectrical
potentials that arise at direct stimulation of the surface of the
cortex (Roitbak~ 1950b). In 1951 Chang, having used a similar method
~~ ~~
(xhiah he described in~detail.and does not substantiate}, published
I ~ \
a number of facts analogous to those on xhich I reported. Recently
articles have appeared of Burns (1951) and of Bishop (Bishop and Clare
1953), testifying to the fact that this aub~ect had attracted the attexttion
Certainly the method of stimulation of the cerebral cortex by-
means of electrodes aet on its surface has many deficiencies. `First of
all, it is quite far from natural conditions of Yts stimulation; then,
at electrical stimulation of the eortical,surface, simultaneous
excitation certainly occurs of many neuronal elements xhich are not
eacited.simultaneously during nor~ml activity off' the cortex. Thus3
it is possible to think that the bioelectrical_xeactions thereby
registered do not reflect normal activity of the cortical elements.
However, it is demonstreited?that?this method gives mn opportunity for
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the clarification of certain questions of the physiology of the cerebral
cortex.. There is nothing unezpected in this, because With the aid of
the method of the electrical stinaalation me~ny important facts have been
obtained Which have riot lost their significance (Fritsch and Hitzig~
1870; Vvedenskii~ 1897; TAchtomakiiJ 1911, et al. ). By the-tray, to
Pavlov belongs the idea~of stadying the action of direct electrical
stimulation of the Qarious points of the surface of the cortex for
effects of conditional stimulants (1926).
A description tii.ll be given further on of the numerous
experiments tr3.th electrical stimulation of the cerebral cortex and
of the registration of the bioelectrical potentials thereby arising,
beginning With comparatively simple experiments and ending ttith those
quite complex in set-up and results.
The e~gxriments rere.made on rats under nembutal narcosis
(2j-1~0 mg. per kg. of freight). 3~e operation consisted of exposing
the larger (cerebral) hemispheres of the brain; the data mater tree
removed directly before beginning the experiments. ~e temperature
of the surrounding air trss~ 30-33'x.
electrodes. 'St(teel or silver. needles served as stimulating
electrodes. lror discharge of the biopotentiala from the cortical
surface silver ones served for electrodes, iror discha~rge~from the
various laarera of the cortez in the first ezpeMmenta~ateel_needles,
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Location. of electrodes'in experimentts Mith sinking of ,the electrodes
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from txo points of the surface oi' the cortex Mas required a special
electrode holder Mas used, xhich presented a plate of pleztglass 7 8
8 cm. in. size. Into the pleziglass plate X1.9 openings xere drilled xith
thread (of screx). After fastening thin plate in the holder, acrexed
to the frontal bone, the diBCharging and. stimulating electrodes xere
screxed into the opanings found, over the points of the cortex involved.
The electrodes xere inata]~led in the following May; to the .silver xire
Tn experiments in xhieh eimultaneouB discharge of the biopotentials
r
~., ~~
sealed xith lacquer to the tip, xere used. Zn subsequent experiments
-discharge Mag effected xith thin electrodes made of ssa~-f`~'~ve%7d constantan
(.a nickel-copper alloy)"? Mire, about 8b mierona in diameter. D sc ge
electrodes xere fixed xith microaarexs to the cranium.
,~~~
xi.th a thickened part of the end crag aolfiered. a flexible isolated
conducting xire on.xhich?are xound several loops of isolation tape;
7~e electrode xas inserted into a metallic tube xith thread (of screx),
xhich xas screxed into the opening in the plexiglass. With the help,
of the electrode holder described it was possible to arrange quickly
and xith great accuracy several stimulating and discharge electrodes
over the-surface of the brain. (Footnote: Recently Daxson (195~?b)
published a deaeript3on of ,the electrode holder xith electrodes extremely
similar to those designed by as (in 195p).)
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into the brain Mss determined by movement. of the microscre~r: Horeover~
in a number of experiments the.diacharge electrodes Were coupled so
that the tap of the first came Mithin? 0.4-1.5 mm. of the end of the
second. When at rotation of the microscreM this electrode vas found
on the surface df the brain} the first entered into the brain to a
precisely determined depth. In a number of cases histological
investigation was made of~this part oP the cortex into which the
electrodes Were driven. In preparations made by Niasl's method it
was possible to find the track left by the electrode; (Footnote:
HiBtological investigations Mere ode by S. Beritashvili.)
Stimulation of the cortex was effected by bipolar, electrodes
~.th 1.5 mm. interpolar diata~nce. The irritating stimuli lasted 0.2
or 0.?5 millisecond. A stimulus that lasted 0.2 millisecond reached
a height of 75y~ after 20 microsecond8 Bind the apes after 60 miero-
`seconds. At frequency increase of the stimulation to 100 per second
the amplitude of the stimuli was reduced 5~r and their character x'as
not altered. '
The bipolar method of stimulation Mss selected as a result
of the fol?7.owing. During unipolar +stimulation under the electrode
located on the surface of 'the aortas there ie a thick field penetrating
the corter:perpendicularly Math a com~ct.cone 'of electrical lines
i3to Mhich the deep layers fall. .At?bipolar stimulation the field
,~
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is far more compe-ct in the region of the surface laycrs_ (Dosser de
Earenri, 193~b), Thus, if the objective is to stimulate the elements
of the deep layers, then it is more advantageous to choose unipolar
stimulation (as xas done in the experiments of Dosser de Barenn and.
Adrian). If the ob~eetive to be pursued is to stimulate surface
layers as isolated as possible, then it is more advantageous to use
gya
bipolar stimvlation.
In the conditions of nor experiments one minute stimulation of
the surface 1,ayers by stimuli 0.2 millisecond in length at a voltage
of 30 volts end a frequency of 70 Per second did not cause any
appreciable irreversible morphological changes of the neuron elements of
the stimulated portion of the cortex (S. Beritashvili, 1952)._
Discharge vas "ur~ipolar".? A thick needle inserted into the
bone over the frontal air-sinue.served as indifferent electrode. As
x111 be.demoustrated, ~.th such a method of discharge the difference
of potentials that is registered is stipulated by the neuron elements
placed in direct proximi.ty?to the "active" electrode (see Renshaw,
Forbes .and [orison, 1910; Eornnt~ller and Schaeder,, 1938; Bishop, 1950}.
The preparation kas grounded; the grounding of the preparation did
not reflect appreciably on the character of the bioelectrical.efPecta
using registered (eee Gardner and i~orin, 1953)? .
Intensification and.-registration. The biopotentiala were
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(la~f,
intensified by boosters 4~ alternating current xith balanced entry,.
i. e. very prolonged electrical fluctuations, if they arise in the
cortex, could not be recorded and~or distorted (see Rogan, 1g~9;
Beritov, Rvav3,lashvili and Roitbak, 1950). Recordings yere made
~~
with a tWO-ray cathode oscillograpli. A series of experiments xere
made xith the use of a booster xith a very great time constant.
A three-ray string oscillograph served for recording.
A'description of the apparatus used, the schemes and charac-
teristics of the boosters of the alternating and direct current, the
deficiencies of the booster apparatus, the possible sources of errors,
the capacity for photorecording and for the marking of time, the
schemes of the relaxation stimuli, the general schemes of the layout
of apparatuses, etc. -all these are given'in,detail in the published
papers of Kvavilashvili (1g~5, 1950) and in Beritov, 2C'vavilashvili,
and Roitbak's article (1950), so Z da not think it necessary to cite
'these data in the present Kork. ~?
? Scheme of stimulation and .d#sci~~e. With the usual .Layout, of
the stimulating and, discharging electrodes on the cortex, stimulation
by even the xeakest currents causes "driving in" (or "atopping.up")
~~L 6~.~ra.~t~
of stimulus the lamp is locked, i. e. the colossal voltage that.
arises becaude of the, polarization of the rtisue; falls on the mantle
(of the .lamp) . Polarization ? currents, that ,of one direction 'being
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under one pale and that o~ the other being under the other pole, arise
around the poles of the stimulating pair for a large territory. Their
amplitude and length are so considerable that if the oscillograph too
is not stopped up, then they cover up the biologics]. effect.
One might think that on the cortical surface points could be
found in xhich the catelectrotonus and anelectrotonus neutralize one
another, as in the nerve there is a portion indifferent 3.n regard to
the electrotonue betxeen the C and A direct current.. Actually this
can be discovered from the start on brain treated xith formalin.
On living brain the problem proved more difficult because of the
conaplea and variable conditions of moisture, blood supply, and other
conditions affzcting the c2~aracter of= tha shunting of the. current.
When the'~discharge electrode lies on the cortex at an equal
distance from each of the txo stimulating electrodes, then at sxitching
on the stimulating current the booster usually is not ahut.off and
in response to the stimulating oertain electrical potentials are
registered that change their character at boosting and increasing the
frequency of the stimulation.and at~changing the direction'of?the
stimulating current.
In Fig. 6 are presented a seriea-of oscillogra,ms shoxing the
xeaults of such experiments. The stimulation and discharge electrodes
are placed on the aigmoid convolution; the distance from the discharge
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electrode to each of the txo stimulating electrodes equals 1.?5 mm.
With an intensity of stimulation of 2 volts and a frequency of 12 per
second the following effect is registered (osc. A); after a'.quick
variation of the ray, Which is c~nsed by the stimulating impulse
itself, a slox potential.folloxs~ Which quickly reaches a maximum
and then almost ezponentially dies out. At ~? volts (osc. B) the
amplitude of the potential is increased; its character remains the
same. This potential expresses iteel.f mainly by a polarization of
the corte$. The discharge electrode in the case in question eras
found under the dominant influence of the cathode, i. e. it recorded
the catelectrotonus. The fact that this is mainly the polarization
potential is demonstrated by the fact that at change of direction
of the stimulat3.ng.curxent the potential, changes its direction
(osc, BZ)s but With this the complete symmetry of the polarization
potentials of~the opposite sign, so characteristic at polarization
of the nerve fiber or of the nerve trunk, is Lacking.
At boosting the stimulation to 8 volts (osc. C)'an additional
? an
potential,Jalter+ed'polarization potential appears: superimposed on
the catelectrotonus is a double fl.uctuation~ oxing to which the total
length of th,e electrical potential is increased. At change?of
direction of the stimulation current (osc; C1) the anelectrotonus
which arises also is represented.by a ~oteni;ial, the direction of
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which is the same as Xith the catelectrotonus.~ Thus, the additional
potential that appears at a certaia intensity of stimulation, super-
imposed on the polarization potential, in distinction fxom the latter
does not change its sign at. change of direction of the stimulating
current.
At increasing the frequency of the stimulation to 25 a second,
the character of the potentials is changed by the course of the
stimulation: the supplementary potential considered gradually Weakens
and then disappears; the polarization potential is left in pure form
{osc. D and D1). Thus, the additional potential is a bioelectrical
reaction. It is po8sible to fudge its form, amplitude, and length if
the polarization potential is deducted from the overall potential
(biopotential
polarization potential). The character of the latter
(at a given 3ntensity~of?stimulation) can be ?concluded through. the
potential which remains after prolonged stimulation of relatively
high frequency ehen the biopotential ceases to be provoked, evidently
from eahauation of the nerve elements. '
At increase of the distance between.the discharging and stimu~,ating
electrodes the amplitude of the potentials being registered; both the
polarization and the biopotential,.is reduced. For inatance,.in Fig. 6,
E, potentials are shown discharged at 3.ntenae~stimulation at a distance
of S mm, from the point stimulated (the discharging electrode in this
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case was in the region of another (cerebral) convolution).
(Tlegend to Fig.. 6, teatpage 28; (~; Here, as in the preceding
paxagraph.s~ Z have used the Hnglish alphabetical sequence from A->~'for
the illustration which thus read doxnxard from left to right; A, B;
Bl, C; Cl, D; D1, E; and F.) polarization and local potentials which
arise at electrical stimulation of the cortical surface. Cat No. 7,
July ~, 19.9. Deep nembutal narcosis. Stimulating (Ag-AgCl) and
discharging electrodes xere p7.aced on the surface of the gyros
sigrnoideus post. Distance betxeen them equaled.l.~ mm. A is an
intensity of 2-volt stimulation. B is of ~+~volts. Bl is of f+ volts
and the other direction of the stimulating current. Cis of 8 volts.?
Cl is of~8 volts and the other direction of the stimulating current. ?
D is the beginning of frequent stimulation (25 per second), l6 volts.
Dl is 1 minute after stimulation. E is the discharge electrode placed
on the gyros suprasylvius at a distance of 8 mm. from the stimulating
electrodes; the intensity of the stimulation is 16 volts. All these
experiments xere made xithout the use of a compensator. Fare the
polarization potentials balanced by means of a compensator. The
biopotentials are discharged from a?point ~ min, distant from the stimula-
tion electrodes; stimulation intensity 8 volts. Osci7.lation upxard
deriotes~negati'vity under the active electrode. Foltage and time
designated for these illustra,tiona : 1 millivolt and. 20 mi 71 iseconcl8. }
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. The recording illustrations ahoxn are essentially like those
which were given in works devoted to recording local potentials in
length of the local potential in the nerve fibers.
of layer I because their length is very great as compared with the
brain the biopotentials do not have their origin in the nerve fibers
incomparably more complca, but arising at direct stimulation of the
HoMever, certainly the conditions of polarization in the brain are
a'nervc fiber (Hodgkin, 1938) and in the nerve trunk (8atz, 19~.7~).
As seen from the recordings presented and as other such
electrical intermediate (neutral) point far from always coincides
considerable residue of unbalanced, polarization potential.. The
electrode. from place to place. Usually it fails to be rid of a
in pure form xhen the "neutral" point is found by transposing the
endeavors have shown, it is very d3f'f icult to record a biopotential
with the geometric, and complete compensation has succeeded in being
reached by mean$ of a compensator. 'In Fig. 7 is presented the scheme
(F.ig. 7, teatpage 80: Sohime of'eaperiment set-up .for registration
of stimulation and discharge used in the present~investigation.~
of bioelectr~cal potentials arising Yn'the neuron element8 of _the
which xere discharged ht a'distance of ~ sea. Prom the stimulating
In Fig. 6, F! are shoirn biopotentiel.a not altered. by polarizatioII,
cortex at it's direct electrical stimulation. Ct. ~? (?our $t.) stimulator.)
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?electrodes. Stimulation and discharge xere?carried out according to
the above-mentioned scheme.
? ? 1. Negative Potentials
At stimulation of the surface of the cerebral cortex of deeply
narcotized cat with electrical stimuli 0,2 millisecond in length and
at a distance of several millimeters in circumference from the point
of~stimulation~it is possible to register the bioelectrical potentials
Comparatively intense stimulations must be used for their provocation:
the threshold of provocation of a biopotential with the stimulation
conditions in. question usually equals 3-~ volts. (Footnote: With the
length of the irritating stimuli at 0.5 millisecond the threshold can
a
be lowered to 1 volt,) The threshold of stimulation of the sciatic
nerve for provocation of the cortical-bioelectrical reaction is usually .
less than 1 volt. Perhaps this is explained by the fact that the nerve
is stimulated at an interpolar distance equal to several millimeters
and the ?brain was stimulated at an iriterpolar distance of 1.5 r?n. Tn
special experiments xith stimulation of the nerve-muscle preparatiozi
of frog it was shown that' at~ reducing the interpolax distance b~1.Q~r~3 mm.
the thresholds of stimulation are increased because of the shunting effect
of the tissue fluid or of the physiological solution betxeen;the electrodes
"(Beritov,,, 1930). It is necessary to think that high thresholds of
provocation of the cortical bioelectrical reaction are connected with
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the shunting of~the stimulation current. ,On the other hand, there
evidently also occurs a shunting of the answering biocurrent {Bishop
and Clare, 1953). Technical difficulty in recording the biopotentials
of the corte$ in answer to its direct stimulation, of which we spoke
above, was aggravated by this circumstance, i. e. b9 the necessity
of using intense atimuiations (up to 30 volts).
The effect of a single stimulation. With deep narcosis one
shock of stimulation or the first shock of rhythmical stimulation
causes a negative slow fluctuation of the bioelectrical potential;
after the negative fluctuation a xeak positive one may follow.
Min3.mal length of a negative potential equals 10 milliseconds (Tig.
8, textpage.31; Bigelectrical potentials registered from the"cortical,
surface near the point stimulated. Cat No.?lOj Odt. 2~?, 1g1?9.
Nembutal. Discharge .and stiawlating el.ectrodea axe arranged on the
surface. of the gyros supra$ylv3.us; the discharge electrode is found
at a distance of 1.5 mm: from the atimulating.electrodea. The
- ~W:
intensity of the stimulation is 30 volts (the threshold $ volts
The affect of the f3xst txo ahocks'? of stimulation sr3.th a frequency
of 16 ~b~~t'~,,(per)~.aecond (see Big. 12,, B). The Brat shock of
stimulation causes a s3.mple negative potential xith a length of
approaime~..tely,l0 milliseconds; the second ahocl~ causes a more complex
effect: a series of additioneel negative fluctuations arise, designated
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by arrows (2,3). Conditions: ?0.5 mfllivo],t, 5 milliseconds graphically
indicated.). The potential quickly, after 2 milliseconds, reaches its
peak and then fa]?1s. Tts amplitude depends on?the functional state of
the settee and can reach 1-1.3 millivolts. During deep narcosis these
potentials are xegiatered at a distance no greater than 5-8 mm., the
amplitude of the potentials being registered gradually diminishing
(rig. 11) at moving the discharging electrode away from the stimulating
electrodes.
The following circumstances show that these potentials are
biological potentials stipulated by the aotivity of the cortical
elements, and not the polarization ones.
].~ At shifting the direction of the stimulating current the
character of the effect is not changed.
2) .7?uring deep narcosis potentials are? not registered from
other convolutions (of the brain) even at a moat proaimsl distance
from,the part being stimulated (Fig. 6). these tWO circumstances
Were already indicated by Adrian (1936).
3) ~ey_oease to be provoked 15-6Q seconds after the heart
has stopped. Chang (1'951) demonstrated that during anozia, Which
,was caused by the animal's having breathed pure nitrogen, they
disappear after 1.5 minutes.
~)~At reducing the temperature of the cortex bales 28'C. and
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at increasing it above ~0'C, their amplitude is reduced; they cease
to arise with the temperature belox 22'C. and above 50'C. (Chang,
1952).
5) They are intensified during local strychnine poisoning (a
0.1~, solution) of the cortex under the dischnxging electrode (Fig. 10,
textpage 33: Changes of the bioeleatrica]. potentials provoked by
stimulation of the cortex after local strychnine poisoning of the
cortex under the discharge electrode, Cat No. 35, Nov, 13, 1950,
Continuation of experiments carried out in preceding illustration.
Stimulation and discharge electrodes Were changed to another area
of the gyrus suprasilvius. Distance {between stimulating electrodes
and discharging electrode = 6 mm. A is the effect of 30-volt
stimulation, 10 per second before poisoning. After this, strychnine
(0.5~ solution) Mss applied to~the brain under the discharge electrode; ,
the poison xas removed after 2 minutes. 8 is the effect of the same
stimulation 3 minutes after the moment of poisoning, C is after 1.~?
minutes, and. D is, after 20 minutes.' After this, strychnine (0.5~C,
solution) Mss applied to the brain under the stimulation electrodes;
the poison lay there for 2 minutes: T is the, effect of the same
stimulation {30 volts, 10 per second) 3'minutes after poisoning. F
is after 4.0 minutes. Conditions indicated in illustrations: 20
miilisecond:e', 0.6 millivolt. (TN:. As before, in translation the
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designations are interpreted Mith $ngliah alphabetical sequence; thus
'by 13.nes: A; B; C and D; E and F.))
6) Bey often~eease?to be provoked during local poisoning of
the cortex under the discharge electrode or under the stimulation
electrodes by a concentrated solution of strychnine, and these
disturbances are reversible (Fig. 9, textpage 32: Changes of bio-
electrical potentials provoked by electrical stimulation of the
cortex in consequence of local strychnine poisoning of the stimulated
Dart of the cortex. Cat No. 35, Hov. 13, 1950. A and B are of the
&yrua suprasylv3.us of the left hemisphere. Distance betxeen stimu-
lation electrodes and discharge electrode is 6_mm. A is the .effect
of stimulation With.a Frequency of 5 per second (30 volts) prior .
to poisoning. After tag, a ball of cotton soaked in a saturated+ .
_ solution of~?strychnine nitrate Was applied to'the brain under the? ?
stimulating electrodes. The strychnine xas'removed after 1.5 minutes,
the brain Was dried at this place and meshed Frith physiological
solution, grid the stimulation electrodes Were placed at the previous
site. ?B is the effect of the same stimulation 2 minutes after applica-
tion of gtrychnine:to the cerebrum under the stimulation electrodes.
The effects frets reduced 30 minutes after taking off the strychnine.
C and E are. .of the gyros suprasylvius of the, right hemisphere.
Distance betti-een the stimulation,electroded and the discharge electrode
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is 6 non. Cis the effect of stimulation (30 volts, 5 per second) prior
to poisoning; after this 'the area under the stimulation electrodes
stas poisoned xith a 0.59, solution of strychnine; the strychnine Was
removed after 3 minutes. D is the effect of the same stimulation 3.5
minutes after aPPli~tion of the strychnine to the brain under the
stimulation electrodes. T is the effect of the name stimulation. 15
minutes after the recording of D. Indication of 0.3 millivolt for A,
of Q.6 millivolt for C. ). In 'the ezpeximents of Beritov and Roitbak.
(195ob~ on sp3:nal cord of frog it Was discovered that at relatively
great concentration of strychnine (general or local poisoning) it
is possible to?observe txo stages of its effect: at first, the
posterior and anterior root potentials attenuates and only after
several rdinutes do they begin. to intensify. Thus} Weakening. of the
cortical negative potentials after strychnine poisoning should be
ascribed to its parabiotic action on the neuron elements. Histological
investigation of the part of the cortez subjected to poisoning by ?
saturated solution of strychnine showed drastic morphological-changes
of the cortical~neu~ons (3. geritashv3.li, 1950? In connection with
xhat has been mentioned abode, it is possible to set forth the following
fact obtained by Chung (1951).s -the negative_potential,ad~usted to be
Provoked S nin. after a strip of paper?saturatsd With a 296 solution of
cocaine rise placed on the cortex beti~een the atinulation and the
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2 minutes after poisoning of the .cortex under the discharge
electrodes by a saturated solution of strychnine.
t~rafstein, 1952: it ceased to be recorded after'~+.8 minutes. In
~ experiments the bioelectrieal potential ceased to be provoked
discharge electrodes. In analogous experiments of Burns and
With a frequency stimulation of 2550 per second the
potentials considered quickly attenuate (see below).
Effects similar 3n character arise at stimulation of any
part of the dorso-lateral surface of the cortex, i.e. the character
of the effect is not appreciably altered in areas of the cortex
different according to functions.
At powerful stimulations and at repeated stimulations addition-
al .negative fluctuations can arise (Tig. 8), but this is not charac-
teristic to'effects during deep narcosis and will be specially
considered in a subsequent part of this chapter.
At a distance of 1.5-2 bnn. between the stimulation electrodes
and discharge electrodes the negative potential sets in 2-2.7
milliseconds after the moment of application,of stimulation. At
removing, the discharge electrode, togethtr with ireduction of the
amplitude of the potential the latent period of its arising is
increased and its character changed: it reaohes the peak more
sloKly. Increase of the .latent period cannot always be detected.
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because of the fact that the interval between the moment of stimulation
and the moment of the arising of the biopotential 1s masked by an
unbalanced residue of polarization potential (this took place in
registration A, Fig. 11). (Legend to Fig. l.]., teatpage 34: Decrement
spread of ne~tive potentials. A is cat Ido. 22, May 12, 1950. B3.o-
currents are discharged simultaneous7.y from a point of the surface of
the gyr. sigmoideua post. at a distance of 1.5 mn, from the stimulation
electrodes (upper curve) and from a point at a distance of 3 mm. from
the stimulation electrodes (lower curve). Intensity of stimulation
25 volts, frequency about 10 per second. B is cat No. 7, Ju7,y ~, 1949,
Gyr. sigmoideus post. Distance between stimulation electrodes and
discharge electrodes 2.5 mm.; the effect of one shock of stimulation
{8 volts}~ Cie the. effect of a single stimulation shock.{8 volts)
._
after the discheu^ge electrode was shifted a distance of. 5 nnn. from
the stimulation electrodes: D and E'are of cat No. 37, Jan. 7; 7.951:
Slight narcosis (6 hours after nembutal? infection).' Stimulation
electrodes P1 are placed at the posterior pole of the gyr. suprasylvi.us;
at a distance of 5 and 71 mm. from them on the surface of this convolution
are placed discharge electrodes El and E2; the second stimulation P2
pair are placed on the surface of the gyr. sigmoideus post, at a distance
of 2 mm. from 7~. In Fig. !' is given the arrangement schema of etimula-
tion and discharge electrodes. The biocurrents~are discharged
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simultaneously from point E1 (upper curvy) and F~ (lrnrer curve). D
is stimulation, carried out through Pl electrode, frequency 16 ?a second
(25 volts). E is stimulation effected through R2 electrodes, frequency
of atimulation?12 per second (25 volts). Indications for .A: 0.3
millivolts 20 mi113~econda.) Fn recordings B and,C in Fig. ll (right
? upper thirds left and right respectively) the effects are shotni of
stimulation of the gyr. aigmoideus. In experiment B the discharge
electrode tree 2.5 mm. from the pair of st3.mulating electrodes; the
latent period of the arising of the biopotential equaled 3.3 milliseconds.
In experiment C the distance bett~een the points of stimulation and of
discharge equaled 5 mm.; the latent period of the arising of the
biapotential equaled 8 milliseconds; If the rate of spread is calculated
on the basis of the differences of latent periods and of th,e distances
in experiments 8 and C} then the magnitude reached is approximately
-0.?5 m. per second. Thum, if it' is assumed that ?the activity` is in any.
tray spread from the point of ~atimulati.on to the point of discharge,
then the rate?of this-spreads on the basis of the above-mentioned
ezperiment~ is of the? order of 0.5 m. per second, t~.7:h. agrees ,frith
Dome's data {199) in respect to the spread rate of potentials in the??
torte= of the cerebellum. Chang thus found that the spread rate of the
negative potentials ccnsidered~in the cortex of cat equaled l m. per
second, (1951);
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According to Adrian and L'hang~ the negative bioelectrical
potential discharged from the cortical surface'of cat at ~.ts.stimulation
is not registered at a distance greater than. 5 mm. from the stimulation
electrodes and is not registered from another convolution even'3.f the ?
distance from the site of stimulation in very small.. ~e recordings
presented in Fig. 11, D and E (lower 2~3 on the lefty upper and lower,
respectively), contradict ~,.hese txo positions. The net-up of the
experiments xas the folloxing: on the surface of the cortex of cat
under relatively shallox narcosis xere placed 2 pairs of stimulating
and 2 discharge electrodes (see F3.g. 11, F (lower 2~3 at the right);
the first stimulating pair (Pl) and the first discharge electrode
(El) are established on the posterior portion of the gyr. sigmoideus
and the second. stimulating pair (P2) and the second discharge
electrode (T~) are placed on the gyr. suprasylvius. The distance Pl
E2 = 11 mm. At stimulation through electrode Pl (experiment D) and
electrode P2 (experiment E) negative potentials are registered in
both convolutions; their amplitude is leas at the more remote point.
Thus, negative biopotentials at stimulation of the cortical surface
can arise at a considerably greater distance from the place of ?
stimulation than ~-as astimated. They ~y arise in another convolution.
We have'thus been confronted with nex facts, Mhich ~ri.ll be considered
in detail in th+e follaring pe~ragraphs , of this chapter. ~ .
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(Pl stimulation) and during spread from the gyr. sigmoideus into the
gyr. suprasylvius'(P2 stimulation). Attention is attracted to the
fact that the rate of spread in the case in question is greater than
in experiments B and C and this can perhaps be connected Xith the
during the spread from the ~y~c. suprasylviu8 into the gyr. sigmoideus
As for the rat? of spread of activity in experiments D and E,
Fig. 11, it is of the order of 0.85 m. per second and it is identical
different depth of narcosis in these txo cases.
According tv Burns' data (1951), in isolated part of non-
narcotized cortex direct electrical stimulation of its surface
Its rate of spread equals 2 m: per second. Thus, the rate of spread
of activity here is even greater in eaperiments.With non-narcotized
cortex. (Isolated from subcortex and from the rest of the cortex,
~ strip of gyry?suprasylvius off' cat, 20 mm. in length, was kept
connected With the~rest of the cortex only by the blood vessels.?)
The fact that at increase of distance between the stimulation
causes the same negative potential as described for narcotized animals.
electrodes and the discharge electrode the 1e.tent period of the
bioelectrical reaction being registered is increased is demonstration
that extremely local biopotentials arise at direct electrical.
stimulation of the cortez. The latent period xould not be increased
xith increase of the distance between the stimulating and the discharging
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trocies'.
limited practically to the region of spread of the stimulating elec-
?indirect provocation of. neuronic elements of the Cortez has been
a distance o~ 2-3 mm. these loops of current could s}~oK such a
stimulating effect on the neuron elensents'as xould lead to the
arising of the potentials being considered. Tl~us,~the area of
current does not occur, at least to ~-uch a degree, in order that at
stimulating electrodes are applied, i. e. shunting of the stimu7.at3.ng
and excitation namely of that point of the cortex to Which the ,
electrical potentials being~regigtered are stipulated by stimulation
shoxs that xith the conditions of stimulation in question the bio-
biopotential is increased at moving the discharge electrode axay
Ukhtomskii, 1911). The fact that the latent period of the cortical
proximate parts of the gray or xhite matter (Fvedenskii, 1897;
stimulation of the tortes is due to shunting of currents to other
its direct electrical stimulation room for doubt has alttays been left
as to xhether or not one or another external effect to be observed at
is limited practically to the, region of their arising.
As kno~ra, during investigations of the cortex by the mathod of
electrodes if the potentials arising are spread simply physically
Frith decrement. Thus, the region of the discharge of these biopotential8
On the other hand, the fact considered (lengtYi of latent period
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in connection xith the moving a~-ay o~ the discharge electrode) shows
the accuracy of the oscillographic method being used. The discharge
electrode shunts,preeisely the bicelectrieal activity of that part
xith xhich it comes in contact. This is-a good argument against
those electrophysiologista who think that the potentials discharged
are alxays the expression of the sum total of a great number of
potentials resultant from the bioelectrical activity of hardly the
xhole of the cortex and that at excitation of any part of the cortex
potentials, purely physical, can be discharged from remote parts of
it, etc.
Very persuasive positions have been exposed on the extraordinary
local character of stimulation and discharge by experiments xith
strychnine poisoning of the parts being stimulated and subject to-
discharge which?were spoken of above. During local point possoning
under stimulating or discharge electrode the bioelectrical effects
that arise at stimulation can temporarily cease being registered. ?
When this occurs es the result of poisoning under the stimulating
electrodes (Fig. 9), this ahoxa the extremely local character of
the stimulation: the loops of current do not stimulate parts?of the
Cortez found at a distance of several n~il.limeters beyond the poisoned
point. When this occurs as the result of poisoning under-the discharge
electrode (Fig. ~10), this shoWS the eztreme~local character of the
'discharge of biopotentials: the discharge electrode does not discharge
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biopotentials from a portion of the cortex found beyond the poisoned
point, from parts in Khich biopotentials of greater am~pl3tude~arise
than those arising .normally under the discharge electrode because
they are found closer to the site of stimulation.
The facts obtained oblige referring quite skeptically to the
possibility of a diffuse and territorially spread phrysical influence
of the biopotentials that arise during excitation of any complex of
neuronic elements, for example to the possibility of the diffuse
anelectrotonie influence of the potent3,als through tissue fluid on
a great number of surrounding neuronic elements, as this was proposed
earlier by Beritov (1937b, 19+8) and by Beritov and Roitbak (lg~8b),
or to the possibility of the anelectrotonic or catelectrotonio effect
of currents of the granular layers of the cortex as was considered
probable by tJkhtomakii .(1939-0 ?
The effect of rhythmical stimulations of the cortex during _
'deep narcosis. (Legend to Fig. 12~ textpage 37'; Negative 'potentials
caused by electrical stimulation of the ~ surface of the cortex t~1.th
different frequency of stimulation. Cat No. 10, October 24, 199.
Nembutal. The discharge electrode and the stimulation electrode's '
are placed on the surface of the gyr. $uprasylvius; the discharge
e]:eotrode is a distance of 1.5 mm. from the stimulating electrodes:
Intensity of stimu3,a,tion 30 volts?(threshold 8 volts). A is a
stimulation'frequenay o~ about 3 per second; B is 16 per second; the
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B1 are effects after 1 minute of atimule,tion. Cis frequency of
stimulation of about 50 per second. C1 is after 30 seconds of
_ stimulation. D is frequency of stimulation of 100 per second. E
is the discharge electrode removed a distance of 2.5 mm. from the
stimulating electrodes; frequency of stimulation at 15 per second
is instantaneously s~itchecrto 100 per second; EL is after one
minute of stimulation With a frequency of 100 per second, and
change-over occurs to a frequency of 15 per second (Roitbak, 195~a).
20 milliseconds and 1 millivolt indicated.) During a stimulation
frequency of 3 per second the subsequent shocks cause greater
effects than the first (Fig. 12, A). With a stimulation frequency
of 10-20 per second growth of effects occurs for the first 0.2-0.~
second oP stimulation (Fig. 12, B); furthermore, the effects are some-
times complicated by additional t~taves arieing.~ At stimulation
frequencies of 50-100 per second the effects progressively and quickly
attenuate and in the course of the first 0.2-0..5 second tetan3.zation
can dwindle to nothing (Fig. 12, C-~).
? When the functional state i$ poor} stimulation of the cortex
provokes negative potentials of little amplitude, With a stimulation
frequency of 10-20 per secamd~the character of effects in?the Course
of stimulation is not changed, i. e, the phenomenon of Sra~-th?in
amplitude of the potentials is lacking (Fig. 13, teztpage 38: Bio-
electr~.cal~potentiale that arise in response to stimulation of the
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Cortez during deep narcosis. Cat No. ~, June 6, l9~?9. Deep
narcosis after injection of a double dose of nembutal. Stimulation.
and discharge electrodes in the gyr.?sigaaideus post.: distance
.betfreen them 3 mm. Intensity of stimulation 30 volts. A is
frequency of stimulation at 8 per Second. B is 15 per second. C
is ~+0 per second, and C1 is after several seconds of stimulation.
D is frequency of stimulation at 80 pex second. 20 milliseconds
and 0.6 millivolt indicated.). At frequency of stimulation of 50
per second the effects quickly dxindle to notb.ing; at a frequency
of 100 per second only the feW first shocks cause appreciable
bioelectrical potentials.
In Fig. 1~+, At an experiment is set forth with cerebral
stimulation at a frequenoy of 25 per second. At first the magnitude
of the effects gro~rs, and after the fourth stimulation shock the
effects progressively attenuate. '1.'he twentieth stimulation shock
causes a three times Weaker potential than the second. In experimbent
B the frequency of .stimulation is momentarily increased to 125 per
second. After slight fluctuation caused by the first shock oP
tetanic stimulation the subsequent shooks produce no effect., T:3
recording C after 2.7 seconds of tetanizatian at a rhythm_of 125 per
second the frequency of stimulation is again Shifted to 25 per second",?
thereby effects arise the Sams in a~plitude as prior to application
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of stimulation at 1~5 per second. Thus these 2.7 seconds of tetanization
have influenced little the character of the effects of the infrequent
stimulation.. In recording D after 3 seconds of stimulation at a rhythm
of 25 per .second when the effects have considerably attenuated.a shift
of frequency of stimulation to 125 per second, xas made, and. then, after
a stimulation of several seconds at a rhythm of 125 per second the
frequency was again changed to infrequent. The effects of infrequent
stimulations after this intensified approximately four times, and
these intensified effects lasted rather long. Thus, the impression
is created that partial repose of the cortical elements being activated
has occurred after a period of tetanization of the cortex.
(Legend to Fig. 1~, tertpage 39; Bioelectrical potentials
provoked during d.ifYerent conditions of stimulation of the cortical
-surface. .Cat, No, 26; June 3, 1850. .Stimulating electrodes?and
discharge electrode'are~placed'on the surface of the gyr. suprasylvius;
distance betxeen the discharge electrode and the stimulating electrodes a
2.5 ~. Intensity of stimulation 30 volts. A-frequency of stimulation
at 25 per second. B - a continuation of recording A; ,the frequency of
stimula,tion?is momentarily sxitched from .25 per second to 125 per second.
C - termination of 2.7-second ?tetanization at 125 per second and.
change to a stimulation .frequency of 25 per second. ~D - after 3.seconds
of stimylat3.on at a frequency of 25 per second a ah3ft 'is mace. to a
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frequency of 125 par second. B -after l5?seconds of tetanization
at 125 per second the frequency of stimulation is chnnged?to 25 per
second. F -the. effect of the application of 30-volt~atimulation
at 20 per second after 1 minute of repose (Roitbak, 19511x). Indications
of conditions on the illustrations 20 mi71'iseconda and 0.11. millivolt.)
- Thus, xe rim into th:e follaxing phenomena. First, xe encounter
ezhaustion when the relatively infrequent stimulations at prolonged
stimulation begin to give gradually attenuating effects. ascondly,
xe run into sharp attenuation or absence of effects xhen there is
an increase of frequency of the stimulation to 50-100 per second.
This is not an expression of ezhaustion, because at lengthening the
interval of stimulation an effect arises im+nediately (see also Fig.
12, E), i. c. xe apparently run into phenomena of the w~orat-beet
("pes~simum-optimum") order-. In the third place, xe run into "repose"
at the time of prolonged tetanic stimulations, but a1so,-as in the
experiments flf Yved:enskii, the present repose is much more effective
than "repose" at the time of the worst ("pesaimum") tetan3zation'~
(Fig. 14, F). .
At consideration of these fadts~obtaine~. during direct
electrical. stimulation of the cortical suri'+eice analogy intrudes
xith the "pessimum-optimum" phenomene~ studied by YTedenskii in
muscle-nerve prepaxation (18$6) .and in? spinal cord (19011?). Hoxever,
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xe later perceive that the correctness of such an analogy can be
confirmed xith doubt.
Patentiala, dfiacharg~ed from different layers of cortex at ~ ,
stimulation of its surface. BelaK are mentioned the results of
experiments xith discharge of potentials from different ].ay~ers of
cortex during electrical stimulation of its surface.
In Fig. l5, A and B, are presented. electrical effects
discharged from the surface of the Cortez at a distance of 2 mm.
from the stimulating electrodes at different intensities of
stimulation. At 12 volts (osc. A) negative potentials arose
xith an amplitude of about 1 millfiv.; at 30 v. the amplitude of
the potential exceeded 1.5 millfiv. and an additional negative
fluctuation arose (osc. B). Then ,the discharge electrode xas
sunk more deeply into the cortex; histological investigation
showed that the end of the electrode xas in .layer V. 'In ~`ig.
15, C-E~ are presented the electrical effects discharged Prom
layer V during different conditions of stimulation of the cortical
surface (the position oP the stimulating eleotrodes xa~a not changed).
At 6 volts tYze effects xere not provol~ed~ xhereas from the surface
xith this threshold intensity of stimulation considerable negative
potentials Mere discharged; at 12 v.~insignificant positive
fluctuations xere discharged from the depths (osc. C)'; at 30 v.
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from layer Y considerable positive potentials xere discharged xith
to the abscissa (osc, E); at cessation of stimulation a slaK txo-
an angpl3tude of 0.75 millivolt (osc. D}. At tetanic stimulation
xith a r}~ythm~pf 5? per second a long positive oscillation xas
obtained, after xhich a negative arose and then the ray came back
phase fluctuation also arose. Analysis of this curve shoxs that
throughout the xhole tame of stimulation a long, oonatantly attenuat-
ing~ positive potential occurred (see Roitbak, 1950x). After these
eaperimcnts the electrode War placed on the surface in line xith
the place of puncture. In response to.atimulmtion negative potentials
again arose of somexhat lesser amplitude than those discharged prior
to deep placement of the electrode (osc. F and G). This indicates
that the ptmcture dcea not damage the cerebral :tissue to any
considerable extent, as xas established by.e~periments on~apinal
discharged from the. surface and fram the depths of the cortex at
(Legend to Fig. 15; ts=tpage ~1: Bioelectrical potentials
ne~tive fluctuation (osc, H) . ,
of 50 per second it is necessary to assume the arising of a long
cord (Beritov and Roitbak, 1948x). A,t atimulstion xitb.a frequency
stimulation of the cortical surface. Cat No. 16, 1~'eb. 11~ 1950.
On the surface of the gyr. euprasTlvius sre placed !tiaulatin6
electrodes and at a distance of 2 mm. from them a discharge
mieroelectrode. The provcoation threshold of the biopotentiala
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is 6 ~. A is 12-v, intensity of stimulations and the beginning of
stimulation is at a frequency oP 10 per second. B is intensity of
stimulation of 30 v. Cis discharge electrode sunk by means of a
microacreW to layer Y; intensity of stimulation 12 v,, frequency
10 per second. D is iritenaity of stimulation 30 v. E is beginning of
brief tetanic stimulation during a frequency of S0 per second (30 v. );
T1 is end of stimulation. ? is microeleetrode raised and placed on
the surface of the brainy intensity of stimulation 12 v.~ frequency
10 per second. G ie intensity of stimulation 30 v, His beginning
of brief' tetanic stimulation at frequency of 50 per second; H1 is
end of stimulation. Condition indicated on illustration at G is
1.2 millivolts.)
(Legend to Fig, 16, textpage 42: Bioeleetrical potentials
-discharged from the surface of the cortez, from the depths of the
cortex, and from the Mhite matter at stimulation of the aur~ace of
the cortex. A is. for cat ITo. 15, Feb, 8, 1980, Biopotentiala are
discharged by microelectrocles from the surface of the brain (upper
curve) end fxom a depth of 0.7 mm (layer curvo};.gyr, supxasylvius,
its posterior pole.. Stiaulating electrodes are placed on the surface
of the brain at a distance of 1.5 ms. from the microelectrodes.
The intensity of atimulatica~rrss Q5 y,, the frequency 10 per secand.
B D is far .cst loo. 27, June 7, -1950. Biopotentietls discharge
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electrodes are found at a distance of 3 mm. from El; frequency of
of the aortas. B is xith.E2 stork to a depth of 0.1-0,2 mm,; stimulating
(loKer curves), Rye stimulating electrodes are placed on the aurface-
from .the surface of the cortex by the very fine electrode El (upper
eurvea) and'from the depths by the needle-shaped electrode E2
stimulation 1+0 per second (25 v, ),
white matters a positive~potentisl is~registered' the negative potential.
Prom the stake and from layier II (osc. B), from the surface and from
the Mhita, mutter (oso, C and D). ' On the basis? of these. experiments
it is possible-to make?lmportant factual conclusions: xhereas from
the suMaee.of the Cortez a negative potential ?is regiatQred~ in the
different layers of the corresponding point"of tie oortex potentials
different in sign?are registered; in layers 'I ana, II there is a r
negative potential; at somexhat greater depth (0.5 mm,) no certain
potential can be registesr~ed~~or a. ~eak? positiva fluctuatiaa is
registered; in layers Y sad. iti~, as, well, asunder. the cortex from the
layers. of oorter, from the surface and from a~ depth of 0.5 mm. (oac. A),
ezperinants M3.th simultaneous diaeharge of biopotentials from different
C is t~ith E2 sunk down to the
rhite matter; stimulating electrodes are found at a distance of
6 mm, from El; frequency of stimulation +40 per second. D is xith a
Prequeaey of stimulation of lQ per second,)
In Fig, 16 recordings are presented that ~rere obtained in
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discharged from the surface being 3.n almost ~rror_imsge formr,
? The "inversion" of the sign of the. potential xhen the discharge
electrode is sunk dat~n into the cortex occurs ar~yxhere close, to the
surface of the cortex, xhiah,shoxs directly that the neuronic elements
,of the surface layers are the source of the neglative potential
discharged f~^om the surface of the aortez.
Adrian 0936) came to such a conclusion on the basis of the
fact that after thermocoagulation of the surfle-ce layers of the Cortez
the negative ,potential in this part ceased to be stimulated. Bishop
and Alare (1953) in ezperiments Xith discharge of biopotentials of
the cortex simultaneously froaa three levels from the surface layers,
the .middle layers, and the t~hite rsatter~ found that at Stimulation
of the surface of ,the Cortez of the upper 1/3 of ~ the corte$ a negative
potential is produced and. at stimulation of the loxer 2/3 either no
potential is produced or the?middle electrode is positive in respect
to the xhite substance. ~ ?
Thus, fram? the facts to be had it' folloxs that' the negative
potential, discharged from the ~urfaee of the..cortez at direct
atiaiu7.ation of , its ezpresses ezcitation of the neuronic elements of
the surface layers o! the Cortez. r
Hiatologid-1 information as layer ,I of the. cortex. At
stimulation of tY~e Cortez by electrodes placed on tts aurPacc, the
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stimulating current should priasrily act on the nerve elements found.
b
on the surf~eice, i. e. on the elements of ].dyer I of the cortex.
? Intormtion on layer I of the aorta=, quite meager in ordinary
teztbocake, can be found in the xorks of 1} Ca~e-1 (1893), 2)Bekhterev
(1898,, 3} and ~+) Lorente de ~o (1933, 1943}, 5} Bliumenav_(1925), 6)
O'Leary and Bishop (1938): 7) Zurabashvili (197, 1849), 8) Sarkieov and
Poliakov (1948), and 9) Chang (1953).
Presented beloM are data ozL the.atructure of layer I, on the
derivation of the fibers of layer I, and on their distribution and
terminations. 8or brevity, literary references are designated by
the ~iguree corresponding to the above.-arentio~ied lint.
At examination ~of cortical preparations ata~ined ~by the Caul
method or by Golgi's method the foll.aring Mell ltnoaa,and; at the
same time, iit~ortant fact is conspicuous: inlayer I of the cartes
the predominant nerve fibere?are those that proceed on a?tangent xith?
r
the surface of the aortas; in layer II dendritic offshoots predominate
xhiah arias from the pyramidal calla of the sub~soent layers. ?
The~fibera of layer I. Part of these fibers are devoid of
medullary membrane, others are n~el.iaated and form thick tufts2'3), .
especially in the upper and.la+ror levels of the layer6). '!fie fibers
arranged in the deepest pwrts of layer I and on the boundary frith
layer II xere described by Belchterev as a rpeoiai layer .of fibers.
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Among the fibers of layer I is s certain number of thick fibers
proceeding for great d.istancee3~. To them apparently belong the
axone of the horizontal cells of layer I, the length of which is
eo cansid,erable that it is 3nspossible to trace them to the end,
haMever large the section may be~~, even ehbuld it measure Several
? millimetereS~, and likewise aaane of cells with the anon proceeding
3~
.
from the subjacent layers of the cortez
Fibers of the outer part of the lager have ma3.nly a direction
diametrical to the length of the convolution, Whereas the fibers
described by Belshterev have a direction corresponding to the length
of the cerebral convolutions. According to Bekhterev, the first
serve as a connection for the tMO xLeighboring convolutions and the
second serve.as a connection between the most diverse parts of one
2}
and the same convo].utiori., often more or less remote from one another .
I,orente de No finds that part of the thick fibers of layer S
do not go beyond the limit of a given cyto-architectonic field, others
3~
.
come from ad~aaent fields
Bekhter4v came to the conclusion that "the first layer of the
cortex genere~llq represents to the h3~hest degree conditions favorable
2~
. C1'I,eary and Bishop, ~0 y~sars at`ter BekYiterev,
to associated. aetivityn
considered it quite, probable that the fibers of Byer Z participate in
the formation. of aesociatian cooties like certain courses. in the white
matter.-
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Origin of fibers of layer I. The fibers of layer I are chiofly
szons or collaterals of different cortical neurone; moreover, collaterals
proceed into layer I of certain afferent fibers. ~e follaxing kinds
of fibers are Pound in layer I.
t
1) The fine collaterals of the associative and collosal fibers.
(This Was ascertained by Bekhterev, and this xas confirmed by the mast
recent histological investigation~a~~9).
2) Collaterals of the aeons of the pyramidal cells of layers
TI=VI2'3'6). In the higher u~mma~lB the horizontal dendrites of the
recurrent collaterals of the cells of the deep layers form in layer
I sturdlr tufts of myelinated fibars~'}. By the flay, Bekhterev thought
the eo7.]mterala of"the cells or the subjacent layers the chief source
of the layer of fibers discovered by him at the boundary of ~.ayers I
and II. ~ "
3} Azons and collatemis of neurons xith a short azon of
cortical layers"I-V13'6}. Concretely, in the forms~tion of layer I
the follc~ing kinds of neurons ~-ith short azon participate:? a)
ce11s xith ascending axon of layer II;~ b) cells tdth ascending ,
aion of lays+rs ,III and IP; c) cells of layers III and IP, similar to
the pyramidal, xith ascending azon;.the azon produces colhtterals
along the xey; d) wall cells xith round forms of layers III and
ITT xith azon rising into layer~I, giving off eollaterals along the-
trey; ej cells of globular form of layers III and,IP; the azon forms
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a pl.eaus around the ce11~ and the?riaing dendrite produces in layer
I several tangential fibers3); and f) cells oY layer V xith the
aeon or Sts collaterals rising into layer 16).
O'Leary and bishop indicate tWO rosin types of neurons With
short axon in the granular layer (IV): neurons xi`.th rising axon
and neurone xith descending aYOn; the axons of the first reach
layer I. Bliumenau attaches great importance to the fact that,
although cells xith rising aaon reach layer'I, they are contained
in all layers of the eortea~ but there is an especially great number
of them in layer TP. We shall come back again to this circumstance.
Dendrites of layer I. In layer I the ramifications are completed
of the top dendrites o! the pyramidal cells o! the subjacent layers.
Aacoxding to Caul, the fibers o! layer I form a netxork in the
meshes, of xhich the?tops of the dendrites terminate, studded., as
~~ekhterev`also confirms thins xith a great number of thornlike off-
shoots to xh:ichs after 8uk~uzOVs 9arkiaov end Poliakav attach
eatraordinsry importances assuming that they serve for contact xith_
the synaptic terminals (6arkisov and Poliakovs 1949; see also Chang,
1952)., The top dendrites st having attained layer Is or somewhat
earliers split iota den,dritie branches, assuming a horizontal direction;
the length o! the horizontal dendritic branches does. not eaceed 2 mm.9'~,:
according to the data to be had.
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Into Layer I enter the dendrites o! the tiny ce118 of layer
II and-thee dendrites of th,e spindle-shaped cells of layers =IT and
IP and ascending dendritic branches oi?certain neurona?xith short
anon from layers III and IV, but likeviae the top dendrite's of the
pyramidal neurons comprise the overwhelming mass of dendrites of
layer I.
Synaptic connections of tha system of fibers of layer I.
It has been found that the thick long fibers_of layer 2, xhich are
the rising axons of the cells of the aub~acent layers, produce a
great number of collaterals that ramify not,~only in layer I but
also in layer I13~ and that the collaterals of the axons of the
cells of layer I (of Cabal's horizontal cells) enter not only into
layer II but even into layer II16}. Nevertheless, Bekhterev
concluded that the top dendrites "present to the highest degree
favorable conditions for association" through contact x3.th the
hranche~s.of the aaons?that penetrate here. Cd~al sax that the
fibers>_of lsy~ar I, particularly the s=ans of the cells of layer I,
terner3nate xith ramifications in the top dendrites of the pyramidal
(cells). Bekhterev presents an illustration (1893, B. 213} in
Mhich are Shawn the top dendrites and ;the terminations ~of the
fibers of layer I on them. Zurabashvili found in preparations
stainsd. for the synapses (s~ccord.ing 'to Hof'f''s mpdified method
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that there are numerous synaptic tui'ts to the top dendrites in layer
II and~the whole layer is strewn Math preaynaptic fibers7~. According
to Lorente de Ro, the top dendrites receive imPulaation chiefly from
fibers of the layer T plezus and not of the layer TI. According to
has data, the number of ryriapees for dendrites of the pyramidal cell
in layer i is 1000 times greater than in layer T13~. 8ynapsee
congrege-te chiefly in the ores of the bifurcation of the dendrites
and in dendritec branches after bifurcation for dendritic offshoots
of the motoneurons of spinal cord of cat; there are fexest of them
in the part of the dendritic trunk imnedi;stely before its bifurcation7~.
Zt is possible to think tb+at analogously for the top dendrites the
greatest number of syna~ptie terminals of the fibers of layer .Z is in
layer T in the region. of their bifurcation anti in their horizontal
branches. ~ .
On the basis of knaxn neurological data in regard to layer .I
of the tortes, it is passible to ~me-ke the ~follaWing conclusions. .
1. In 1,ayer T there are medul].atsd and unmadullated fibers
attaining great length. These fibers connect with ane another the
adjacent convolutions, the different parts of a convolution, ad well
~as the,d~.fterent cortical fields.
2. Ttiabifurcations of the fibers of layer Z terminate
prineipally in layers Y And IZ of the torte=. In layer I they form
.numerous.aynaptie terminals in the top dendrites of the pyxamtcira,l
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neurons. In layer Ix they participate in.i?he formation of a complex
netxork of fibers terminating in the neuronic elements of layer II and,
among them, in the trunks of the dendrites oi' the pyramidal ael].s.
3. At stimulation of the fibers of layer I activation occurs
mnin7.y of the dendrites in layer I of the cortex. Thus, in the
corte$ of the larger hemispheres (cerebral) there are anatomical
reasons for the possibility of Hare or leas isolated activation of
dendrites, a clarification of the function of xhich is the present
problem of nettrophysiology.
~+. Since the fibers of 1,ayer I proceed mom the pyramidal
neurons of all sub~aent layers of the eortea and from the cells xith
axon ris3,ng from all $ub~aeent layers of 'the aortea, then, consequently,
the top dendrites of the pyramids can be?activated from a vast number
of sources; eaaitation of the neurons of any layer of the Cortez can
be traneferrea through the system of the~fiberB of layer=T to.the,
tops of the dendrites of the pyramidal net~ona.
Origin of negative.biopotentials discharged from the cortical
surface at direct electrical stim~,ilation of i:t:. , It can be considered
established that the alo~- negative potential arising directly in
response to electrical stimulation of the surface of the cortex
e~cpresses mainly the state of eiaitation. of the dendrites ~ke-
~~es-~oi the cortical surface layers and is a "dendritec potential".
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Beritov came to this.conalusion in 19.1 on the basis of the data
of Adrian (Beritov, 191). Chang (1951), Eccles (1951j, and. Bishop
and Clare (1953) have arrived at the same view.
The faets.obtained,in experiments with stimulation of the
different layers of the cortex testify in favor of this, that the
arising of negative potentials at stimulation of the surface of
the cortex is connected With ezcitation of the elements of layer Y.
Stimulation of the cortex vsa made by the "unipo],ar" method, by
during atimulati.cn of the middle and deep layers can be ezplaj.aed by
the Yact`~hat stimulation thereby occurs of the collaterala and a$ons
of f~bera of layer I ~.s found. The arising of the negative potentials
from the surface of the cortex in resporiae to the stimulation a
negative potential i-aa discharged. At ainlsing the electrode further,
i. e. at stimulation of, the middle and deed layers of the cortex, fxom
the, surface of the ,cortex xaa registered (at a given intensity of
stimulation) a negative potential of far less?ampl3tude than at
stimulation of the surface layer of the'eortez (Burns and Grafstein,
1852). R~us, th,e ?greateat activaition of the top dendrites oceure at
~tt3.n[ulation of the surface layer of the cortex in which the ayetem
a depth of 0.1,0.E mm., then during a certain intensity of stimulation
When the.stimu].stion electrode Was on the surface of the cortex or at
imcpulses 0.5 millisecond in length, and by means of a glass microelectrode.
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that rise into layer I or of thrr corresponding ce11s oP these layers,
i. e. by the fact that the system of Fibers of layer I is again thereby
excited.
Slox negative potentials are recorded even during deep riercosis-
at aconsiderable distance Prop the part of the cortex stimulated,, the
Latent period oP their arising being more prolonged in the more remote
points than in the more prozinal. The following fact can serve as
proof that the spread of these potentials through the cortex is
connected with the spread of the ezcitation by the elements of layer
I: after incision of the cortex betxeen the stimulat3.ng electrodes
and the discharge electrode to a depth oY_0.13 ~., the negative
potential ceases to be registered (Burma send Cirafstein, 1952}.
In layer I there are, as said, ramifications of the top
dendrites and of the system of the tangential fibers,- The?lerigth '
of the horizontal dendritic branches inlayer I does. not exceed
2 nun. (Chang, 1951); consequently, it is Pitting to thank that the
spread of the negative slox potentials occurs by means of the Fibers
of layer I. The rate of spread~of the slox potentials is determined,
thus, by the rate of spread. o! this excitation along the fibers oP
layer I. It is knoKn that the very fine fibers of the peripheral nerves
aoaduct th,e a=citation nt a rate of the order of 0.7 meter per second,
i. e. at a rate, Mh,ich approal.m~tes that xith Mhich? the activity in `the
surface leiyers oP ttLe cortez is spread during deep narcosis. ~ ,
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The rate of spread is considerably altered in connection xith
change of temperature of the sorts=: at 29-32'C. it equals 2 m. per
second, at 26' 0.7 m.~ per second, and: at 22' 0. ~ m. ' persecond (.Chang,
1952).
Tccles in a survey article on the basis of literary data also
ezpreases the opinion on it that activation of dendrites at stimulation
of the surface of the cortex should proceed through the fibers of layer
I (Eccles, 1951). However, Dom even earlier proposed a similar
clarification to the spread of activity arising in the cerebellar
cortex during electrical stimulation of its surface (Dox~ 199).
At intensification of the electrical stimulation of the cortical
surface increase of amplitude occurs of the negative potential being
registered. 7~is iaust be explained by the fact that at increesin~ ,
the intensity of the. stimulation the number of fibers excited in
layer T increases. As a result of this, in the area of discharge
the number of synaptic terminals excited, under~Which excitation
in the dendrites arises, 3a~increased. ~e amplitude of the dendritic
potential is increased in connection Mith intans3fication of stimulation
up to a certain, liffii.t~ neverthelasa.~ grarrth of amplitud,~ of the
- -------- -- -.????~. ?.~.,.. .+J ~.ac uwnuvr vi ay~ptilC tierasna
~s?.,
of ].aver I to 'the dendrites of the. discharge portion.
Clarification, according to xhich activation of the,. dendrites ig
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realized thraiagh the fibers of layer I, ran into difficulty, ~+hich
consisted of this, that the quick (potential) rhich itself eapresaes
the current of effect of the excited fibers of layer I (see recordings
of the dendxitic potentials 3.n all the trorks published and in the
above-mentioned oscillogranis) does not precede the slow dendritic
potential. gtill in a number of cesea it proved possible to register
the effects of direct stimulation of the surface of the cortex in
trhich the quick potential of complex character, trhich consisted off'
a group of asynchronous in[pulsea of anon origin (B'ig. 17), preceded
the slag negative potential. This initial component is altered in
connection w3.th the :change of direction of the stimulating current
and in connection~tiith change of place of stimulation, 'i. e. at
change of the conditions of stimulation of the surface of the cortex.
At prolonged stimulation ~t a rhythm of 50 per second msny components
' ~ a
of thin initial effect fall out.
The fact that quick potentials tiers not usually registered
before the slox is probably explained by the poor conditions for
discharging quick fluctuations from the surface of the cortex.
' of
' At the mov3.ng~the disehi-rge :electrode at~y from the point
stimulated the anq~litude of the dendritic potentials being registered
is reduced, ~.. e. there is 'observed,. as it here, a log~e-rithmie decrement
spread of~the activity. .~ecles explains this phenorenon by the manner
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of spread of fibers of layer I. This must be comprehended in the
follaxing xay: for ezample, eaaitation f'~om the part stimulated
comes to point A through 10`fibers of layer I. From col?7.?terals of
these fibers the dendrites placed here are activated, part of these
fibers terminating than and'thare. Impulses are admitted to point
B through 6 fibers, to point C through 3, etc. The degree of
decrement of the dendritec potential is proportional to the decrease
of the fibers ezcited.
As xe have seen, nat only the rate of spread, but also the
degree of decrement and., consequently, the distance of spread depend
on the depth of narcosis. During deep narcosis dendritic negative
potentials are registered in cat at a distance of 5 mm. from the
site af.stimulntion. In Bursa' ezperiments (1951) an isolated
strip of non-narcotized cortez.it xas registered at?a distance of
10 mm,; in the recordings presented as obtained on slightly x~rcotized
animal it xas at a,distance of 11 imn.
We,._have seen that during deep narcosis and generally at decline
of the functional?atate of the Cortez first the activity begins to
?spread to an even lesser distance and, secondly, its rate of spread
is reduced. ~.s is perhaps connected xith the e=Yect of the narcotic
on elements responsible for th+e spread, ~,.e. the fibers of layer T.
It can be thought that these fibers. are verb sensitive to the. action
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of the narcotics and fall into a parabiotic state. Furthermore it
is possible to assume that the stimulation applied to them at this
time causes excitation which spreads x3.th decrement along the fibers.
and their collaterala; the attenuated biocu~rents of the torminals?
closest to .the oollaterals~are still capable oY shoxing a stimulating
action on the neuronic elements and of stipulating the arising of
local potentials.
Thus, electrophysiological and histological data permit
concluding that electr3.ca1 stimulation applied to the surface of
the corte$ leads primarily?to excitation of the fibers of layer I.
The excitation, spreading along the fibers and their collaterals,
reaches the synaptic endings that are located mainly on branches?
of the top dendrites of the pyramidal neurons; the dendrites are
activated and generate bioelectricsl potentials ~-hiGh are discharged
fxom the surface of the cortex close to the point stimulated, it
the form of negative potentials. - ?
(Legend to Fig. 17, textpage ~+8; Quick potentials before
slaw potentials. Cat.No. 32, July 10. 1950. The discharge electrode
is placed on the .surface of the gyr.. ?sigmoideus: A -~ effects
rcgistered.?when a point of the same convolution yas stimulated at
a distance of ?l0 ~ from the discharge electrode. B -effects
registered ghen a point of the, same convolution ~+as stimulated at a
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'distance of 8 mrn. from the disoharge electrode (intensity of
stimulation in both oases 30 v. ).)
Chsng proposes an entirely different eap7.anation for the arising
and spread of the potentials being considered. The slrnt negative
potential (discharged in his experiments at a distance of up to 5 mm.
from the stimulating electrodes) ezpressea the dendritec potential
itself, provoked by direct stipulation of the horisontal branches
of the top dendrites. The negative potential is registered When
the ezoitation impulses arrive through the branches of the dendrites
from the site of their stipulation wod.er the discharge electrode.
The spread rate of these potentials corresponds to the excitation
spread rate ~in the dendrites (Chang, 1951)?
8oxever, as~saidt;the horizontal branches of the top dendrites
have, a length no greater than 2 mm.;~in the experiments of Chang
himself the potential teas defeated at a distance of-5 mm, from the
site of stimulation and in?the case presented,in Fig. 11~ D and E,
the potentials mere registered at a distance of 11 ma.~ a fact vhich
it is by no means possible to eap1,~-in from Chang's comment:
' The position that the dendrites potentials 'arise at stimuLe~tion
of the surtfe~ca of the sorts=~ grovaked by direct stimulation of the
det~drites~ Chang supports by, the-. fcllo!~in8 facts : 1) ? in oomiection
~-ith intensification of the atimulatian of th+e cortsz the 'amplitude
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of the dendritie potential relatively quickly reaches a mazimal
magnitude. Chang thinks that if its origin xas stipulated by
transmise~ion of the ezeitation to the dendritic synapses, then
the amplitude off' the potential.xould be increased xithin immeasurably
greater 13mita. 2) Dendritic potentials are not appreciably changed
under the effect of strychnine. This fact cannot, hrnrever, serve as
proof of the fact that dendritic potentials arise during stimulation
of the cortical surface xithout the agency of the synapses. It is
xell knoxn that strychnine does not appreciably change the amplitude
and character of local potentials of the motoneurona (arising through
double neureanic axcs, i. e. directly under the influence of afferent
impulses) as xell as of local potentials arising in the elements of
layer IiT of the cortex under the effect of afferent impulses (see
the strychnine acts on selectiw~ely in the sense of elevation of
ezaitability:
al~+ays connected xith excitation of the intermediate neurons, xhich
~of the surface of the cortex. ~e apasm4dic strychnine effect is
same too in reapeat to dendritia potentials provoked by stimulation
Chaptex IV). Under the influence of $tryahnine a certain increase
occurs of the amplitude of these local potentials, but xe see the
It~~s already been said that the aegA~tive potential is registered
from the surface of the cortex and during point stimulation of the middle
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sunk into the cortex. In the opinion of burns and Grafatein (1952)
at a distance of several millimeters from the -stimulating~microelectrode
and deep layers of the Cortez, the negative potential being registered
-this fact shows that the negative potential ari~sea xithout participation
of the fibers of layer I, that it is stipulated by excitation of?the
horizontal branches of the top dendrites, i. e. they think that dur~8
stimulation in the depths of the cortex the top dendrites are excited
and then the excitation spreads along their horizontal branches in
i.~yer I of the cortex. HoMever, this fact is easily explained otherwise
if it is taken into consideration that the fibers of layer I arise
from the subjacent neurons, chiefly of the middle and deep layers of
the cortoz. It is not remarkable that at stimulation of these elements
negative potentials arise: excitation spreads along the ascending
axons (.or eollaterals),~ then along their horizontal branches in layer I
and stipulates the arising of 1oca1 potentials in?the top dendrites
on Khich the fibers of layer I termina:te? synaptically.
With the method of stimulation used and with YiarcoBia,?stimulation
of the motor area of :the cortex did not lead to the arising of movement,
Whereas from the surface of the motor area of the cortex around the part
stimulated slow negative potentials of greeter amplitude xere registered.
Thus, iri the dendrites of the pyrami.dsl~neurons excitation arose. The
pyramidal neurons'as a whole.vere not excited. Ao diacharge~ of
excitation into their a-zons occurred, i. e. into~the pyramidal courses.
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-93-
It is characteristic that when a ne?ative potential is diaeharged.
from the surface of the cortex in ,response to stimulation of the Cortez,
then in the name part of the cortex, from the mieroelectrode found at
the level of the cellular bodies of the larger pyramidal neurons (at
a depth of 1.3 mm.) quick dischaugss are sever registered (Burns and
Grafatein, 1952).
It is knaMn that if by thermocoagulation the upper three layers
in field ~ die, then at stimulation of this part the same motor
reactions are provoked as prior to destruction by layer; the threshold
of electrical stimulation is not thereby altered. After destruction
of ali lay+era of the Cortez, only very poxerful stimulations provoke
a motor reaction because of direct stimulation of the xhite matter
(Dosser de Barenne; 1933as 1930? Since the threshold of provocation
of the motor reaction vae not change3 after thermocaagulation, then,
aonaequently; during the ,given.conditiona of experiment reactions xere_
provoked laecause of direct stimulation of the cellules elements, of the
deep }sayers. St is also kno~rn that the threshold of provocation 'of
motor fieactians trhen there is stimulation of the motor vortex depends
on 'the .method of stimulation (Dosser de Barenne, 193~+a): at unipolar
stimulation it is lamer then at bipplar stimulation, at Mhich electrical,
' ~~~'..
lixses run mainly through the dendrites of the pyraaidal cells,. Hence,
it is_possible to conclude that isolated stimulaticn of the ,dendrites
does not lead to eze~.ts-tion of the ~correeponding cellular bodies.
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-~-
On the basis of the_data of Clare and Bishop (1954) it likexise
. ~ is possible to conclude ttlat when the'top dendrites of the association
pyramidal neurons undergo direct electrical stimulation (stimulating '
microeleetrodes at a depth of 0-0.3 m~a.), then discharge of excitation
impulses into their axons does not occur; when the {cellular) bodies
of the association pyramids (the microeleetrodes xere sunk into layer
Iy} are stimulated directly, then diaoharges of impulses in their
axons arise under the effect of the same stimulation.
The facts obtaizied in experiments with simultaneous registration
of biopatentiala from different layers testify that when excitation
arises is the dendrites wader the effect of ia~ulses from the fibers
of ].e~y~er T, the (.cellul,ar} bodies of the pyramidal neurons are not
aroused by impulses into the axons; likewise, no local excitation arise~~
4
in. them that Mould be expressed in registration of a characteristic
negative potential from elements of the deep layers. Consequentlg,-
excitation of dendrites of the pyramidal neuron does not lead toy
excitation, spreading or regional, of the rem~sining parts of the neuron
('cellular body and axon). Thus, when excitation in~ulsei~ come to?the
top dendrites of?the pyramidal neurons, the rsactioai is lisited by
the arising of regional excitation of the. top dendrites.
With itbak single stimulations of the cortex and ~-ith deep
narcosis and strong atisulation,s a simple~bioelectrical reaction
.arises, a negative biopotential~ the miaisal length of which is .
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equal to 10 milliseconds.. ~e minimal length of such a negative
ypotential developed by the motoneurons and-by the intermediate
neurons of the spinal cord of cat is the same.' On the basis of
this it is possible to assume that the length of the elementary
local potentials i.,e. of the regional?ezcitation, is approximately
identical for the:varioua neurons of the central nervous aystem~
for instance for the neurons of the spinal cord and of the cerebral
cortex. Footnote: fit direct electrical stimulation?of the optic
covering of frog the negative potentials discharged from its surface
likewise have a length of about 14 milliseconds (Roitbak~ 1952).)
On the basis of experiments x3,th simultaneous discharge of
biopotentiels from the various layers of the cortex it was concluded
that the level at'Which alteration of the sign of the potential
occurs lies some'Where close to the surfaces apparently at -the
boundary of layers II and III: a negative potential expressing
regional excitation of the dendrites is~registered only from layers
I-II {Fig. 16). At deeper'placement of the discharge electrode in
the cortex, they stop discharging e~ny considerable e~'fects or they
cYLange their sign. Hence, it is.possible to conclude that xegional
excitation {and?a local potential corresponding to?it) arising in ,
the top dendrite does not spread=doirrntards?through the dendrite for
any 'considerable distance and th~-t it is virtually. limited to the
' place of its arising' under the excited. synaptic endings. If~ We
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Were persuaded earlier of this, that bioelectrical potentials are
extremely local in respect to spreading along the surface'of the
cortex and that the loops of stimulating current xith the stimulation
method in question are not spread through the Cortez to such a degree
as to cause excitation of` the nerve elements at a point of the Cortez
laying in line xith it, then too it is possible to conclude in regard
to the physical spread of the biocurrents and of the stimulating
currents in the depths of the eortez: this issues from the possibility
indicated of isolated activation of surface layers oY Cortez. Hoxever,
finally, in natural conditions of activation oY the cortex isolated
activation of the surface layers cannot proceed. As xe have seen,
the main source of the fibers of layer T consists of the ascending
axons of cells With short anon and the recurrent eollaterals of the
pyramids. , Thus, the excitation of; the fibers .of layer I and the subsequent
activation of the top dendrites (and other elements of"the surface layers)"
presumes the preliminary excitation of the neurons of other layers of
the cortex, particularly of the neurons of layer N, Which is the'main
regional ending of the aff'exent f 3bera of the corr~sx.
Thus, on the beBis of an analysis of the dendritec potentials
the dendrites provoke in,_them regioml'nonspreading excitation; 2?)
basic theoretical conclusions: 1) excitation i;gpul~es,arriving at
of. the .pyramidal neurone. it is possible to melee the follo~ring txo
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regional. excitation of the top dendrites does not lead to excitation
of the corresponding pyramidal neurons. (Footnote: This conclusion
Mss msde.on the basis of the results of pointed experiments Mith
exposure of the cerebral cortex. Hence, as A.E. Kogan pointed out,
the folloMing ob3ection is possible:? during exposure of the cortex
the top dendrites fall into a psrabiotic state and, in response to
the inrpulsea that come tv them, respond xith regional excitation.,
8ormall.y they conduct excitation to the body of the cell.} These
conclusions agree Mith the conclusions of Beritov concerning the
activ3.ty of the dendrites, that Were made on the basis of an
analysis of numerous facts from the histology and physiology of
the central nervous system~(eee Beritov, 1941, 1948, 1949, 1953)?
They da not agree Mith the prevalent concept, according to Mhich
the dendrites conduct excitation to the body of the cell. and even
are detectors "collecting" the straam of nerve impulses from different
sources and transmitting them to the axon (Gesell; 3.940;?Poliakov~
1953)?
In virtue of the .fact 'that the pyramided neurons ?~-ere oriented
vertical to the surface of the cortex, experiments ~`r1.th deep sinking
o! the dischsrg+e microelectrode from the surface aP the cortex vertical
to the Mhite matter permit concluciing~ona.thE.profile of the outer '
electrical fields Mhich arises`~at regions'! ezcitatioa~ of the dendrites:
..?
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points around the part excited, i.e. around the top dendrite, are
negative, and the points around the cell. body~and axon are positive
in respect to the remote "indifferent" point (Fig, 18, textpage~52:
Potentials opposite in'sign, recorded from different parts of the
pyramidal neuron at excitation of its top dendrite. P - stimulating
electrodes on the surface of the cortex. 0-.01 - conditional level
at ~~frhich the "inversion" of potential. occurs. The scheme floe con-
structed on the basis of results of electrophysiological experiments.)
Beritov thinks that d?nclrite~s do not conduct excitations
because the fine, bare bifurcations of the dendrites develop an
active process of little intensity, and this process up to the body
of the cell is not in a condition to spread,'ow3.ng to the biocurrent
that thereby arises {Beritov, 1948, 1949). Hoxever, it can be thought,,
in addit~.on, that the neuroplasm of the dendrites is different in~its
properties from the neuroplasm of the cellular bodies. For instance,
the various staining properties of the cellular bodies and of the
dendrites to be detected even frith Nisisl's method indicate this. ~~
Finally the fact that excitation of the dendrites during natural
conditions of their-stimul:ation (i. e. under the effect of the excitation,
impulses conducted tb them by the fibers) does not lead to excitation
of the neuron is perhaps :ezplained _likefrise by the fact. that the
presyriaptic.fibers-terminate differently on~the polies of the neurons
and their dendrites {see ~belofr) ..
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Sherrington concluded that the axon type of excitation
conduction is natural not?only to axons of nerve celZe but also
to their bodies and their dendritic offshoots and?that the synapse
by its unique structure is capable of changing'th3:s type o?
excitation conduction. In regard to the dendrites, this conclusion
was made by him on the basis that the dendrites may be nerve fibers
having cerebral-spinal ganglia in the ~orm.of a neuron (Sherrington,
1906. However, as Malone rightly notes (1932), it is necessary
to distinguish relationships in the central nervous system and in
the posterior-root ganglia and it ie impossible even to assume that
dendrites of the central nervous?system are sim3.lar in their properties
to sensory-nerve fibers.
Up 'to the present time the~idea~that dendrites of all neurons
conduct excitation in a way similar to that by Khich the peripheral
nerve fiber conducts i~t Kos prevalent, but facts obtained by oscillographic
study of the central nervous system h~i3!e led recently to a change? of
opinions on this +atatement by a number~of American physiologists:
Chang thinks that at electrical stimulation of the?top,dendrites
excitation spreads not only through their horizontal branches, but
also through the dendritee trunk daWnvards to the body of the pyramidal
neuron at the rate of 1-2 m. per second. ?Excitation of the dendrites,
according to Chang, is normally transmitted to the body of the pyramid
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and then to the Gaon. Hoxever, during narcosis the excitation of the
dendrites does not provoke excitation and discharge of the corresponding
pyramidal cell,'since blockade occurs of the excitation at the site of
the transition of the body of the cell?into an axon. By this is explained
the fact that the. shock of electrical stimulation applied to the surface
of the motor area of the cortex, provoking a negative potential, does
not provoke a motor reaction. Nevertheless, as xas pointed out, the
local potential is registered only at the level of layers I and SI.
Thus, there are no bases for considering that the excitation reaches
the body of the pyramidal neuron and is blocked at the place of
emergence of the axon.
The difference in methods of activation of the pyramidal
neuron,, through the cell body .or through the dendrites, according
to Chang; consists of this, that because of the lox rate of excitation
condu>vtion through the dendrites?the.latent period of excitation is
in the second case considerably ~by. 3.5 t~ii113seconds, in has estimation)
greater (Chang, 1951}.
Hoxever,, later on and issuing from hiatolagical data on the
presence-of tKO types of synaptic connections betxeen the cortical
neurons ~ the axosomatic and the rszodendritic,. Chang came ? to several'
other vl.exs. Tai his opinion, in connection xith th,e fact 'that
presynaptic fibers terminate on the body of 'the pyramidal neuron,
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xith numerous thickly distributed synapses e~ccitation of these fibers
usually causes the discharge of the pyramidal neuron in question;'
presyaaptia fibers on the dendrites of a pyramidal neuron terminate
with a moderate number of linearly distributed synapses, and excitation
of these fibers usually does not lead to the discharge of the pyramidal
neuron in question; the discharge can proceed with simultaneous
,,;
excitation of a great number of paradendritic synapses (Chang, 1952}.
At excitation of the body of the pyramidal neuron the excitation
spreads, according to Chang, on the one hand, into an axon, and, on
the other, upKard through the dendrites to the surface of the corte$
(Chang and Saada, 1950). Thie universally adopted point of viex,
according to which the dendrites. conduct the excitations 3s also held
by Lorente de 1Vo. On the basis of a study of the biopotentials of
neurons of the nucleus of.a sublingual nerve at theSr antidromic
excitatian, he came to the conclusion that the rate of spread of
excitation in the nerve cell ('body of the cell + dendrites} 3s of
+~,a? n,~r ~~ 2 m. roar second. Se thinks that the antidromic impulses
spread along the dendritec bifurcations by?.the same principle as in
the nerve~~'iber~ i.e. because the current of excitation subsequently
stimulates portions of dendrite~a along the travel line. oi' the excitation.'
I,iketirise, he cang3,ders "the question unsolved, ~thether imcpulses 'reach
the very fine biftiircations of the dendrites (T,orente d.e Ida,. 197}.
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Bishop and Clare (1953) on the basis of the data obtained in
experiments with discharge of potentials from different layers of 'the
cortex at stimulation of its surface formed the conclusion that
dendrites of pyramidal neurons do not conduct excitations do~raward
to the body of the cell, i:e. entirely the same .conclusion as was
made by me on the basis of like experiments. HoWever~ on the other
of the cortex, they reached the conclusion that dendrites of pyramidal
neurons conduct excitation from the body of the cell upward to the
hand, on the basis of experim~snts xith stimulation of the deep layers
(i. e. to the body of the cell), but antidromically (i. e. from the body
surface of the cortex. ~r~e still come back to paradoxical conclusions,
according to which dendrites do not conduct excitation orthodromically
of the cell).
`~
(Legend to Fig. l~, textpage 54: ~ppressi~on of
"spontaneous"
electrical, activity during~~stimulation of the surface of the cortex.
Recordings Aand B -cat No. 26, June,3, 1950. Relatively deep
nembutal sleep. The stimulating electrodes and discharge electrode
are placed on the surface of the gyr. suprasylvius. The discharge
electrode is a distance of 2.5 mtg. from the stimulating electrodes.
A _ ~ginn~,ng of tetanic stimulation (.frequency 50 per second,
intensity 30 v. ). B -after 10 seconds of tetanization; end~of
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'Recordings Cand D -cat No. 2~, May 20;.1950. Relatively
deep nembutal sleep. The stimulating ,electrodes (P) are placed on
the gyr. sigmoideus post.; potentials are discharged simultaneously
from a point on the surface of the same convolution at a distance
of 2 mm. from,P (E1, upper curses) and from the surface of gyr.
suprasylvius 10 mm. distant from P (E2, loxer curves). D -beginning
of short tetanic stimulation (50 per second, 25 v. ). D -end of
stimulation. T -scheme of arrangement of electrodes (Roitbak,
1953x).)
T.nh.ibition of "spontaneous" electrical activity. In the
course of investigation xe xere repee~tedly confronted ~3.th facts
evidently related to the phenomenon of car?bical inhibition.
At the time of stimulation?of the surface??of the cortex at
a rhythm of ,50-100 per second, attenuation and even coiaplete oppression
of "spontaneous" electrical activit~t (Fig. 19)?can occur; reduction of
it occurs after 0.5-1 second throur~h cessation of stimulation.
r~!
? :pppression of "spontaneous" electrical activity proceeds at those
points of the cortex at xhich negative slox fluctuations occur 3n
response to-st3anulation, i.e. during deep narcosis this occurs?in
a small territory around the stimulating electrodes. At those points
of the cortex there the stimulatsion in question does?not cause
negative biopotentia~ls '"sponta,neoua" electrical activity is not
~~//
altered (F,ig.-19, G and D)?. !Oppression of "spontaneous" electrical
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activity at tq~ltanization of the surface of the cortex occurs too
~-hen, as a consequence of local etrychninization, this activity is
sharply intensified (Fig. 20, textpage 55: Oppression of "spontaneous"
electrical activity at stimulation of the surface of the cortex. Cat
No. 12, Dec. 2, 199. Stimulating electrodes and discharge electrode
on the surface of the gyr, auprasylvius;, distance between them 2 mm.
11 minutes after local poisoning of the brain under the discharge
electrode with a O.l~i solution of strychnine. A -intensification of
electrical activity (after poisoning) and beginning of tetanic
st3anulation (50 per second, 25 v. ). B - immediate continuation of
recording A. C - electrical activity 0.5 second after cessation of
stimulation. For this period of 0.5 sec. the electrical activity
remained depressed.).
On the basis of the facts cited it is possible to assume that
oppression of-"spontaneous" electrical activity during tetanization,
of the surface of the cortex is causally connected with the negative
slow poteritials~arising thereby, i.e, thatappreasion of "spontaneous"
electrical activity is stipulated by ezcitation of the dendrites in the
surface layers of the cor-tez.
It would be possible to give this phenomenon another explanation
by admitting that the "spontaneous" activity is -stipulated mainly by
the act~.vity of the nerve elements of the surface layers of the cortex
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and that the elements activated as a result of the tetanizing
stimulation no longer produce rhythmical fluctuations of "spontaneous"
activity. However, it is knoxn that after thermocoagulation of the
upper two layers of the cortex "spontaneous" electrical activity of
the part in question does not disappear but only attenuates somewhat
(Dosser de Barenne and MacCulloch, 1935, 1936). Recently it xas
established that during con~aratively xeak stimulations of the surface
of the cortex at 50-100 a second a prolonged negative potential of
a nonfluctuating character arises (Beritov and Roitbak, 1953)? 'i'he
ar~Iitude of this potential is increased at increase of frequency of
the stimulation and reaches 1 mill3.v. and more. The slox negative
potential reaches a maximal amplitude 1-1.5 seconds after the beg3xming
of tetanization~of the surface of the cortex and-lasts 3-~} seconds;
gradually attenuating, (Fig. 21, tegtpage~56: Long potentials of
nonfluctuating character that arise during electrical stimulation of
the surface of th,e cortex. Cat under deep nembutal narcosis. On the
surface of the gyr. suprasylvius the stimulating electrodes xerje~placed
~7 ; f Y~1,V' ' 1 ~1 v~~.}4,~ E(tR'
and 3 and 10 mm. distant from ,the diaeharge electrodes. Hooste~r with
~?-
a `gr-ea~r_ time constant. Le~ngth~ of 3~i~fteot#ng stimuli 0.5 millisecond.
A -frequency of stimulation 9 per second. B~-- frequency of stimulation
50 per second. C - eficct of repeated stimulation after 10 seconds.
Intensity of stimulation in ezperiments A - C 10 y. 'D - Intensity of
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stimulation 5 v., frequency 100 per second. Deflection upward
denotes negative character of discharge electrode very close to
the point of stimulation (Beritov and, `~#oitbek, 1953). ). ?
tilith the beginning of the development of the pegative potential
the "spontaneous" electrical activity immediately attenuates or ceases
and remains oppressed throughout all the time of the beginning of
this potential. Thus, regional, fixed, nonfluctuating excitation
of the system of dendrites in the surface layers of the cortex
stipulates inhibition of activity of the neuronic elements of the
cortex.
On the other hand, during comparatively intense stimulations
of the surface of the cortex at a rhythm of 50-100 per second a
prolonged positive potential can arise that is attended by intensification
of the "spontaneous" electrical. activity (Beritov and Roitbak, 1953).
tahen from~the surface of the cortex a long negative biopotential
is discharged, the inner layers of the cortex are polarized iii a positive
gray (Fig. 15). It can be thought that activation of the dendritic
plexus of 1:ayers I and II stipulates the-anelectrotonizat3on of the
cellular bodies of the pyramidal neurons in the inner layers of -the
cortex and by this very thing oppression of "spontaneous" electrical
activity.
The facts obtained at passage~of a~conatant current through the
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Cortez can serve as argument for the correctness of this assumption
(Burns, 19511). If to a sma11 part of the surface of the Cortez an
anode aas applied, then with a current energy of about 100 microamperes
excitation occurred of the cortical neurons. This phenomenon did not
arise with a reverse direction of the current. In another series of
experiments a microelectrode Was introduced into the cortex to a depth
of 1.2 mm., i.e. into layers P-YI. When it was connected With a
cathode of constant current, then an eaeitatian arose of the cortical
l,;
neurons. When it was connected With the anode, no excitation arose.
Intense rhythmical stimulation of isolated non-narcotized strip
of cortex aroused excitation of neurons of the deep layers of the pert
stimulated, With prolonged aftereffect. If at this time to the surface
of this part of the Cortez a cathode of constant current Was applied,
then the aftereffect broke immediately. The same effect"Was obtained
if the anode Was applied to the ~microelectrode introduced into layers
Y-VI of this part of the Cortez. Thus, during negative polarization
'of the.aummit dendrites inhibition occurs of the activity .of the
pyramidal neurone of .a g3.ven point of the cortex as a consequence of
positive polarization of their cellular bodies: the catelectrotonus
of the dendrites is.associe~ted With the ~anelectrotonus of the cellular
bodies. ,Is it ia~ossible to compare this phenomenon With pericateleetro-
tones, With the phenomenon of anodic reduction of the ezcitability in
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-108-
the 'region of the neuron adjacent to the xegion of the eatelectrotonus?
? On the. basis of the facts dust cited it ie possible to conclude
that during artificial polarization of the cortex when the cathode
is on its surface there is created an electrical field the same in
configurat3.on as in the case of natural ezcitation.of the top dendrites
through tetanization of the fibers of layar I that bring about their
excitation.
? Vorontsov (19+9) thinks that at ezcitation of the dendritec
ramifications very xeak currents should arise that may shoK only an
insignificant effect on the bodies of'neurona. Hoxever, he considered
the results of excitations of the very fine ramifications of the
dendrites. We too have seen that dur3.ng regional excitation of the
top dendrites 'of the pyramidal neurons a positive potential of great
amplitude, is registered from the bodies of?these neurons.
In connection With What has been said above, the fblloking
fact which We have already mentioned is of`interest. In experiments
Stith registration of?biopotentials of the individual motoneuron
through a microelectrode inserted therein it has been established .
that'when exciting afferent impulses reach the zmotoneuron, then an
ordim.ry local. potential (ueg~tive)_ arises in it, t~hich xe have
already spoken of above. When inhibiting?afferent impulses arrive
'at the natoneuronj then~a poaitiv+e potential of the same length and
form. as the nepettii-e local "potential is registered from the mAtoneuron
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(Eccles, 1952, 1953)? Thus, the process of. regional excitation and
the process of inhibition have an electrical display opposite in sign.
Proceeding from the dendritic hypothesis o~ inhibition (Beritashvili,
1953~),?it ia,neaesaary to assume the~t inhibited impulses are impulses
coming to the synaptic endings on dendrites-of the motoneuron. The
body of it is .thereby polarissci. in a positive way, as xe astir in regard
to the body of the pyramidal neuron during regional excitation of its
dendrites {see Roitbak, 1955, fbr more detail).
Contribution to the question of the lability of the dendrites.
As known, the higher boundary rhythm of excitation is the standard
of lability (functional liveliness). With characteristics of lability
these bring a reaction xhich is most specific to the tissue in question
(Ukhtomskii, 1939-~+0}. The lability of the nerves is determined by
the higher.rhythm of the currents of effects since the excitation
that is spread is most specific to their reactions. As xe have seen,
regional ezcitation far the dendrites is a specific reaction,?and if
the same principle is applied here, then the lability should be?`
determined by the higher rhythm of the local potentials.
`The higher rhythm, so determined for the .,dendr~.tes is equal at
leap narcosis to 100-125 per second. The lability quicklydrops in
the course of stimulation: the rhythm of stimulation (50-100 per
second} is reproduced only at the ver~i?beginning of stimulation,-then
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the effects quickly attenuate and go daxn to nothing (Fig. 12).
Thus, stimulation frequencies of 50-100 per second for the cortical
surface can, as it,~Were, be noted as the Worst; the optimal xill be
frequencies of 10-20 per second.
on What principally are these terminations found?~ The nerve fibers,
summed up during stimulation of the aur~ace of the cortea~ in the
fibers of layer I, in their synaptic endings, or in the dendrites,
cord it is in the intermediate neurons. But When this state is
experiments of Seritov and Roitbak (1950x) on strychninized spinal
in the motor neurons of the anterior horn. In the oscillographic
In experiments on it ~-ith strychninized spinal cord (1904) it is
In 9vedenskii's experiments Mith nerve-muscle preparation
(1886) the trorst state `ran sunmrsd up in the nerve-muscle lamina..
the conductors, always possess greater. lability than their station
of destination. This evidently is the general rule and the fibers
of Layer I of the cortex, in spite of the fact that~the heater part
there are also factual~inc'lice-tions that during prolonged several-
of them are devoid of my~elixi,; hardly present an exception. .However,
second atiaulntions of 'the surface of the cortex at a rhythm oi' S0-
100 per second the nerve fibers of layer I continua conducting
excitation and transmit it through. the synapdea-to the neuronic
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Thus, it should 1? concluded that the phenomena of intensification
and of attenuation of the bioelectrical potentials being considered during
changes of frequency of stimulation of the cortical surface reflect the
very processes occurring 3.n 'the dendritic offshoots of the pyramidal
neurons.
Certain: preceding discussions lose their significance 3f the
original position is inaccurate, that the higher rhythm of the local
potentials is the criterion of lability for the dendrites. Indeed
can the rhythn of local potentials testify unreservedly to the
functional liveliness of the dendrites or of the cellular bodies?
As said, at application to the spinal sensory nerve of subthreshold
(in the sense of provocation of the reflex discharge in the motor
?nerve) shock of~stimulation in the corresponding motoneurons of the
spinal co%;d a regional excitation or~local potential develops and ?
,.
after 10 milliseconds attenuates. Sf stimulations are applied with
such calculation that From each subsequent shock of stimulation
afferent impulses come to the motoneurons even to attaining the
preceding local potential in its height, then the phenomenon is
? observed of suneuation of local. potentials: a nonfluetuating slox
potential of greater amplitude arises, i. e. "the curve of the bioelectrieal
potential no longer ref7.ects the rhythm of tha stimulation. Hrn(ever,
-it is absurd to consider this the expression of the Horst state of
the motoneurons, since dust the phenomenon of sunaw~tion of regional
stimulation lies at the basis of the excitation, of the discharge of
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the neurons. The same refers also to the local potentials of?the
nerve fibers. Dendritic potentials cease to arise through the
rhythm of stimulation at irritability frequencies of ~0-100 per second,
..but it is incorrect~to consider these frequencies as the worst. A
nonfluatuating potential thereby arises, the amplitude of which is
higher than the amplitude of the elementary dendritic potentials
that arise at individual shocks of stimulation. Sts amplitude is
increased at increase of frequency of stimulation within the limits
of 20-100 per second. This nonfluctuating dendritic potential is
not an epiphenomenon, but is connected, as we see, with a process
of inhibition.
Certain high frequencies of stimulation at xhich?a~nonfluctuating
potential arises less in intensity and length than during certain ,
lower frequencies can perhaps be considered as the "worst" frequencies
in regard to local potentials. For instance, in the egger3.~ents of
Delov and I~apitskii (1935)?the slox potential discharged from the
surface of the spinal-cord of frog during stimulation of the sciatic'
nerve at a stimulation frequency of 100 per second reached an amplitude ,
of 1 milliv. and. lasted for a long time during uninterrupted stimulation,
At-a stimulation frequency of 200 per second the potential after a
?the slox nonfluctuatirig potential discharged front the surface o~ the
small rise (0.3 milliv.) quickly dwindled to nothing. Or'; for instance,
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medulla oblongata of frog during stimulation of the sciatic nerve
has at, a ~ stimulation frequency of 100 per second a lesser~Wamplitude
than at a frequency of 10 per aec~; at a f~Tsquency of 100-per.
eeeond during unintei-rupted~stimul,ation it quickly attenuates,
~rhereas at a frequency of 10 per second it preserves far a long
time its initial aaSplitude {Roitbak, 1952}~
2. Supplementary Negative Potentials
During deep narcosis the bioelectrical patential$ that arise
in response to direct electrical stimulation of the surface of the
cortex are relatively siri~le and constant. They are altered from
intensity: frequency, and duration of stimulation in a certain
siurple dependency on these factors, ~rhich bras painted out in the
first part of this chapter: Hrnrever~ at light narcosis in a xay _
liko that by Which motor reactions on the terminations are complicated
and~beeome altered (but~not stereotypic as they are at deep narcosis ?
.i~rom direct electrical stimulation of the motor area of the cortex `
{~khtomskii, 1911, the bioelectrical responses of the cortex are
-complicated and become altered. at direct electrical stimulation ~of it.
These complex bioelectrical effects xill be examined further on.
Further back a detetiled e~nalysis eras given of those potentials
simple in character xhich,express regional excitation of the ?top ..
dendrites of the p3'z'arnids that sets in immediately under the effect
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of impulses from the fibers of layer T. The characteristic bioelectrieal
reaction to stimulation of the cortical surface during deep narcosis
is a negative biopotential of 10 milliseconds' duration. For instance,
~in xecordings A and B of Fag. 12 the first shock ~of stimulation causes
this simple bioslectrical reaction, a negative potential lasting 10
milliseconds and reaching an amplitude of 0.75 milliv. Subsequent
shocks with a stimulation frequency of 3 per second {recording A) and
16 per second {recording B} cause potentials of greater a~plitude
(1.2 milliv,) and of greater duration {up to ~0 milliseconds).
The increase of amplitude and duration of the.. negative slow
potentials occurs because of the rise of additional negative fluctuations.
In Fig. $ are indicated the first 2 effects of stimulation at a rhytshm
of 16 per second. Additional fluctuations are indicated by arroxs. '
The first shock of stimulation causes~an elementary dondritic potential
not complicated by supplementary fluctuations. The second shock provokes
a more complex e~'fect: the elementary negative potential ,is complicated
by two additional. negative Fluctuations. They arise on the descending
part of the potential and-stipulate increase of the length of the effect.
At a stimulation frequency of 1 per second and less the effects.reme~in
simple: and in response to eingle?shocks of stimulation stereotypic
responses arise. '
Su;pplem+entary fluctuations can be expressed not only in the
fprm of "humps" on the 'background of the mein dendritic potential but
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can be fluctuations of considerable amplitude sharply .separate from
.the first negative potential. During certain conditions their
amplitude can considerably exceed the amplitude of the initial negative
potential.
(Legend to Fig. 22, teatpage 60: Supplementary negative
potentials. A, B~ and Q -cat Ho. 23, May 17, 1950. 6timulating
electrodes and discharge electrode on the gyn. suprasylvius; 2.5
mm. between them. Stimulation frequencytabout l2 per. second. A -
stimulation intensity of 5 v., B - 10 v., t3 - 30 v. D -cat No. 30,
July 1, .1950. Stimulating electrodes are placed at the anterior
pole of the gyn. suprasylvius; at a distance of ~ and 10 mm. from
them in the same convolution are placed the discharge electrodes E1
and F~. The potentials are registered simultaneously from point El
('lower curve) and E~. Stimulation intensity 30 v., frequency 10 per
second. E -cat No. 9, July 28; 19+9. Distance between stimulating.
electrodes and discharge electroiia ~ mm. Intensity of stimulation
16~v., frequency about 13 per second. ?' -after one minute of
stimulation, .El -effect of txiee.aa powerful stimulation 30 seconds
after the heart has stopped. t~ -cat ao. 32, July l0i 1950. .Stimulating
electrodes and discharge electrode are placed on the gyn. gigmoideus
post. (P - ~ :.4 1mn.-~. Stimulation intensity 30 v.,.frequency 10
per second: Stimulation did not provoke motor reaction of the~animal.~
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These supplementary waves arise first in connection with
intensification of the stimulation. (Fig. 22, A-C), secondly, as we~
have already seen, in connection with the inexease of frequency of
the stimulation, asrl.finally in connection with repeated stimulations
spina]. cord (Beritcjv and Roitbak, 1950b~).~)? During strychninization
the latent period of a supplementary fluetuatiiin~ is reduced. (gig. 2~?)
An analogous conclusion was made on the?Uasis of experiments on the
intensification occurs of local potentials, i.e. of. regional excitation.
effect of strychnine indicates that under the effect of strychnine
certain intensii'ication~of the initial 'negative potential under the
the initial rie~,at3.ve potential increases very little (Footnote: A
additional fluctuations are extremely intensified (Fig. 23), whereas
a supplemeni'.ary negative potential. Under the effect of strychnine
but already the?Eth shock and all subsequent ones ceased to provoke
2d, 3d; ~-th,'and 5th, shocks of stimulation caused double effects, ?
the latent period of their arising is?reduced. During Prolonged
stimulations the supplementary fluctuations attenuate in a greater
measure than the initial negative potent3:a1. For instance, in one
experiment, the beginning.of which is presented in Fig. 22, D, the
(Fig. 22, .D).
During stimulation at a rhythm of 10 per second these additional
fluctuations can be intensified through the course of the stimulation
(Fig. 22~ D and G). :Sn a number of cases in the course of the stimulation
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and it can unite kith the firsts as 'the result of ~rhich a .single
prolonged potential arises. Duri7dg etimu7-at3on at ?a rhytbm pP 10
per second alternation of effects complicated by gigantic supplementary
fluctuations can be observed xith sinXple~effects (Fig. 23~, i.e. ~ ?
during repeated stimulations supplementary fluctuationst intensified ?
under the effect of the strychnine can separate out (co~pa,re Chang,
(Legends on teatpage 62, Fig. 23; Effect of strychnine on
cortical bioelectrical effectrt caused by electrical stimulation of
the cortex. Cat No. 28, dune 10~ 1.950. Nembutal. Stimula,t3.ng
electrodes (P} - on the gyr. supre,sylvius. The Potentials are
discharged from the same convolution at a distance of ~ mm. from
P (E1, upper curves) and from a point of the gyr. supre,sylvius of
the oppos3.,te hemi~phere~ sy~imetrical to the point stimulated (E2,
laver curves). St3,mulation frequaney 10 per second, intensity 30 v.
A -prior to poisoning, Band C - 5 minutes after local poisoning
with strychnine (l~i},' of point ~. D -effect of stimuYation, at s _
rhythm of 3 per Second after poisoning of point $1 Xith a saturated
solution of strychnine. .'
_ 93x.'24; Effect of strychnine on the bibpotentials of the
cortex that xere provoked by its electrical stimulation. Cat~No., 12,
Dec. 2, 1949, Nembutal. The stimulating electrodes and discharge
eleatrode~ are ? placed on the gyros suprasylviue; the ~di.echarge electrode
is found at a distance of ~2 ndn. ?from the stimulating electrodes. ' A -
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the effect of a single stimulation (25 v.) prior to poisoning. B -
10 minutes after local poisoning of the cortex under the discharge
electrode by O.l~i solution of strychnine. C - 15 minutes after
poisoning (in experiment C - 3ntensif icat3.on is,reduced).~
During very light narcosis or in experiments on non-narcotized
preparations the vezy first shock of stimulation produces comple=
effeats~xith supplementary fluctuations ~Fgi. 25, textpage 63;
Bioelectrical potentials registered on the surface of the cortex
near the point stimulated in non-narcotized cat. Cat No. 31, July
~, 1950. The larger hemispheres (the cerebrum) are revealed, the
spinal cord is intersected at the boundary of the medulla oblongata,
artificial respiration. P-E1 distance = 3 mm., P-E2 : 7 mm.
Stimulation intensity 30~v., frequency,IO per second. A is the
beginning and B the end of brief stimulation (shortly after this
recording the functional state of the eortez xorsened greatly).).
The facts cited permit concluding that the supplementary
negative potentials are stipulated. by the activity of the intermediate
cortical neurons. This ind.icatest
1) Their disappearance during a xorsening of the functional_
state of the eortea.or their sensitivity, to narcosis. As Chang- "
(1951) pointed out, during anoxia supplementary fluctuation disappears
after 1 minute; the initial negative potential, as already?said,
disappears after 1,5 minutes. ?
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2) Their quick attenuation during long ezhaustive stimulations.
3) Their intensification in. connection xi.tb. intensification and
increase in frequency of the stimulation.
~) Their senstiv3.ty to strychnine.
gistological information on layer II of the aortea. Axonal
plexus of layer II. ~In layer II there is a complez plezus of anon
terminations in xhihh the short axons of the cells of layer III the
collaterals of the fibers of layer I, and the ascending axons of the
cells of layer III participate (Lorente de No, 1933)?
Types of cells of layer II. 1) Star cells (modified pyramids).
These are cells of average size ~r1.th numerous dendritec offshoots
proceeding in all directions and supplied with spines. The axon runs
into tYie White matter, givin8 off 6--10 collaterals- into laye~s,,I, II,
TII, V, and YI {Lorente de No, 19333 O'Leary and Bishop, 193a~.
2) Cells with horizontal aeon. They are di~t~Buished i`roni
the preceding by their axon: .it has a horizontal direction and gives
off a great number of short collaterals that spread into. layer Il.and
terminate, according to Lorente de No, on the bodies of the star cells.
3) Cells w3,th ascending axon. They~are of a leaser size.
Their dendrites apread.3nto layers I and II', but the azon, at having
attained layer I, divides. into tWO tangential fibers, each of Which
gives off callateral$~ (Lorente de 'fto, 1933)
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~) Cells. With dendrites proceeding With two tufts into layers
I and III. The anon or its branch proceeds into layer III, terminating
there around the ~ ~pyramide (0'I,sary and Bishap, 1938) .,
In Fig. 26 layer II is schematically presented, its neuronic
elements and their connections. (I,egend? to Fig. 26, teatpage.6~:
Schematic depiction of the neurons of layer II of the cartes and of
certain of their connections. 1, 2, and 3 are the main types of
neurons o~ layer II of the cortex. 1 is a neuron With ascending
aeon. 2 is a neuron With horizontal axon. 3 is a neuron With
descending axon and collateral returning into layer I (star cell},
The scheme Was composed on the basis of certain histological data.)
On the basis of certain histological information mentioned
above about, ].aver II of the cortex it is possible to make the follox3ng
conclusions:.
? 1. During?eacitation of the system of fibers of layer I
excitation of the cells off' Layer II can occur, because in layer II
there are numerous collaterals of'the fibers of layer I. -~
2. During excitation~of the cells of layer II activation can
occur of the top dendrites inlayer I, beee-use among the cells of
layer II are cells xith anon ascending into layer?I, xhich.take on
there a horizontal direction and give forth many aollaterals. In
additions the ~aonis or tl~e star pyramids give forth coll.aterals into
layers ?I and II, .
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3. During excitation of the ce11s of lnyer~II activation can
occur of elements of the deep layers of the cortex, since the axons
~of the 'star pyramids give forth collaterale into layers III, Y, and
VIA and certaiin cells xith short axon of layer IT terminate in the
Pyramids of layer Ill:. ,
4. During excitation of the horizontal cells activation should
proceed of the entire complex of star pyramids ands tba2iks to the
latter circumstance, intensified activation of the deep layers.
Origin of supplementary negative fluctuations. There is no
doubt that the supplementary ne~tive fluctuations in the effects
that arise in response to stimulation of the surface of the cortex
are .stipulated by excitation of the intraaortical neurons. Histological
data give indication that they should be stipulated by the activity
par excellence of the neurons of layer II of the cortex. The
._ mechanj.sm of their arising in the simplest case can be connected
xith excitation of the cells of layer II xith_axon ascending into,
layer I (Fig. 26 - 1).
During stimulation of the fibers of layer I impulses of
excitation proceed first to the sy~ptic endings of the fibers of
layer I for the top dendrites and, secondly, to tbe~cells of layer
II with ascending azon~ the endings and collaterals of trhich form
additional synaptic fields for the top dendr~ttes. As ~a result,
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inanediately in response to the stimulation, the first negative
fluctuation arises, already designated by us the elementary
dendritec potential, In the cells of layer II there also arises .
a regional excitations and (When there is a good functional state
of the neurons), when it reaches a certain size, these Neurons are
discharged by impulses into their ascending axons, which stipulates
additional "iacpulsation" to the top dendrites of layer T, the
arising in them under the synaptic endings of the ascending axons
of a regional excitation, and the arising of a supplemrentary nega-
tive fluctuation in the effects being registered.
During participation of ce11s with short axon that branch
for n Short distance in the limits of a given layer (typical Golgi
II ce11s~, cells which are extremely numerous in all layers of '
the cortex, an association and involvement in the reaction of the
neW complexes of cells With ascending soon can occur, s~hich readily
explains the fact of the arising of a series of supplementary
fluctuations:
Excitation of the neurons of layer II proceeds as a result
of the spread (in connection With intena~?fice~tion of stimulat~.on~
or of the temporary (in connection with increase of frequency of
stimulation) eumsation.o~ excitation. Frequency of 10 per aecond?
is evidentl.,y, an, optimal frequency, of stimulaticni. for excitation of
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these neurons governing 'the arising of additione~l negative
potentials. - ~ -
- During strychnine poisonings in consequence bf the elevation
of excitability, a greater number of 3.ntraeortical neurons are dra~+n
into reaction-and their activity is 'synchronized. A. result of this
is that for the top dendrites of the pyramids there sets in at each
stimulation an incomparably greater number of impulses from the
intermediate neurons. Because of this intensification of a secondary
negative fluctuation and the arising sometimes of a whole series of
additional fluctuations occur.
.At stimulation of the surface of the cortex (durixsg ezcitation
of the fibers of layer I) not only neuronic elements of layers I and
II can come into an active state but also the neuronic elements of
the deeper-~]~ring layers as a result of the excitation} for ix~atance~,
of the star pyramids of layer II (Fig. 26 - 3).~ This should lead.
" A
to the arising of neW bioelectrical phenomena, to a consideration
of ~hich~We shall proceed in?ediately.
. - - 3. Positioe Potentials '
At placement of the discharge electrode more deeply into the
middle and deep layers of the cortez the sign of the potential
provoked by stimulation of the surface of the cortex changes.- To
this phenomenon teas given an eaplanation~ neGOrding.to Which this
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-124-
arising in the dendrites of the pyramidal neuron of a local potential
ands consequently, of a difference of potentials between the dendrites
and the other parts of a given neuron leads to positive polarization
of the latter, 3.e. of the cell body and azon. It is possible to
think that in vase of the arising of a regional ezcitation in the
bodies of the pyramidal neurons a positi'v~e potential trill be registered
from the surface of the Cortez (from their tap dendrites).
(Legend to Fig. 27, teztpage 66: ~e arising of positive
potentials 3.n connection with increase of frequency of stimulation
of the surface of the corteu. Cat No. 27, June 7, 1950. Gyrus
suprasylv3.us. Distance between discharge electrode and stimulating
electrodes ~ mm. Intensity of stimulation 30 v. A -frequency of
stimulation 15 per second. B -frequency of stimulation ~0 per
second. )
Adrian in his work8 with stimulation of the surface of the
Cortez and registration of the bioelectrical reactions arising?
established that during a?good functional state df the cortex shocks ?
of stimulation, for instance at a rhythm of 10 per seconds provokes
?negative potentials at first, then the sign of the potentials changes,,
i. e. positive fluctuations begin to arise, the a~plitude of~xhich.
groKS?in the course of the stimulation,_ the potentials may become
more camplez in connection frith the arising of additional positive
fluctuations (Adrian,?193d)..
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This phenomenon ~aa observed too in ~ experiments. Conversion
of negative potentials ta.positive in 'the course of the stimulation
occurs the more quickly the pare frequent the stimulation up to a
certain limit. At a stimulation frequency of 10 per second this"
can proceed on~l.y after several seconds bf stimulation, as this xas
in one of the experiments of Adrian. At a frequency oY ~0 per second
this can proceed after 0.2 sec. (Fig. 27), but in one experiment
this proceeded after three shocks of stimulation {Fig. 36, C). On
non-xro,rcotized rabbit it is possible to observe hon-eeven at a
frequency of Stimulation of .3 per second the effects after several
seconds of stimulation change their sign. On ne~rcotized cats this
change usually ,occurs only at a certe~in relatively greeter frequency
of stimulation (20-50 per second). At lesser frequencies of
~,~ i
stimulation this phenomenon does not arise however much the stimulation
has ;been prolonged. For?_insfance, in the experiments certain recordings
.of Whieh are-=presented in Fig.. 28 it i~as~ 'established that during
several-minute stimulation at a rhythm of 1 per second the effect of
its character did not change (~ose. A}. (Legend to Fig. 28, textPa6e
67: The arising of positive potentials in connection with increase
of frequency of stimulation oP the suacface of the .cortex; Cat .Fo. 56,
July 16, 1953. Rembutal. The stimulating electrodes and discharge
electrode ere astablis2ud oai'the surface of the gyrus~auprasylviuS;
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distance between discharge eleetrode and stimulating electrodes 5 rmn.
Intensity of stimulation 30 v. A -frequency of stimulation about 1
per?second, B - about 5 per second, C - about l0 per second. .D - about
25 per second; 0.5 second after the beginning of stimulation. T~ - 10
seconds after beginning of stimulation. Recording by SchleifP oscillo~
graph.} At a frequency of stimulation of 5-10 per second,, in spite
of the fact that complea,double'i~egative potentials ar'dei, i.e in
spite of the e;coitation of certain complaaes of intermediate cortical
neurons, no change occurred of the sign of the biopotential; at
prolonged stimulations progressive attenuation occurred of a supple-
mentary fluctuation (ose. B and C). At a frequency of stimulation
of 25 per second the negative potentials began quiokly and progressively
to attenuate (ose. D}, and after several seconds of st3~mulation each
shock provoked a quite positive potential (osc. E}.
In certain preparations a powerful single stimulation can
immediately provoke a positive potential of greater amplitude, arising
after the artefact of Stimulation. It is interesting that in these
cases at a frequency of stimulation of 10 per second only the_firat
shock of stimulation provokes a positive potential;,the second and
. all subsequent shocks of stimulation provoke negative potentials
(Fig. 22, C). _
Positive potentials, considerable,in amplitude, can arise
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-127-
after a supplementary negative potential (Fig. 28, A and.B).
? According to Chang, preceding a,aupplemcntary negative potential
is a positive one, i.e. in response to stimulation a negative potential
arises that passes over into a positive one, after which a second
negative fluctuation follows. This actually can occur (see Fag. 15);
but this is not the rule; supplementary negative fluctuations can
arise without the preliminary first negative potential having changed
to positive (see Fig. 22).
Finally,~a positive fluctuation (Fig. 23, C) can precede the
initial negative potential, which Chang (1.951) also points out.
In the majority of cases after the negative potential a low
positive deflection is observed of considerable length. It is
d3,fficult to say whether it always expresses activation of the
elements of the deep layers, since it i,s observed also during deep
narcosis. ?Perhaps this is?the analogue of the subsequent positive
potential'after regional excitation. Such resultant potentials
arise, as al.~ady said, in the nibtoneurons.
The following data regard. the 'positive potentials that arise
at stimulation of the surface of the cortex.
_ ~1. In experiments on isolated strip oP?cortex the following
facts xere established.- When .the Cortez Mas not narcotized, then
in response to a shock of stimulation applied to the surt'ace of the
cortex.a brief negative potential arises (30 millisec'onds), after
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which a positive potential folloxs that lasts 2-~? seconds; on its
background fluctuations arise at a frequency of 60-75 per second.
At lig}it narcosis these Pluctuation$ drop out and a long positive
potential ar3.ses in pure form (Burns 1951). During deep narcosis '
the length of the positive potential is shortened to 0.1 second,
i. e. in response to a single stimulation the txo-phase effect already
described arises: after the negative potential a positive one arises
oY less amplitude and greater length (.see, for instance, Fig. 8).
At sinking the discharge electrode deeper into the cortex the
positive potential discharged from the surface of the cortex changes
its sign at a depth of 0.~? mm. 7~us, that the positive potential is
connected xith the active state of the elements found. belox layer.Il
of the eorteg is directly demonstrated (Burns, 1951). At the mLcro-
electrode being sunk in deeper, the positive potential attenuates,
then changes its sign, i.e. a negative .potential is registered. The
latter reaches Sts greatest amplitude at a depth of .about 1.3 mm.
It 3s characteristic that the amplitude of the negative potential
at this depth exceeds the amcplitude of 'the positive potential
discharged from the surface of the cortex (compare'recordinga a and
d,?Fig. 29, textpage 69, the legend to xhich reads Bioelectrical
potentials discharged by the microelectrode?from,different lsyers
of the cortex at stimulation of its surface. Isolated strip of
cortex of cat xi,th circulation preserved: The glass microelectrode
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-129-
xas ~ mm. distant from the stimulating electrodes, and later on it
Was sunk. more deeply into :the~corte~. The indifferent electrode
was placed an a thermocoagulated part of the cortex. The surface
of the cortex was stimulated With a single electrical stimulus.
Booster frith a more fixed time. a - Microelectrode on the surface
of the cortex; b - microelectrode is sunk to a depth of 0.59 mm.;
c - at 0.72 mm. ; d - at 1.5 mm. ; e - at 2.03 nun. Deflection upward
signifies the negative character (Burns and Grafstein, 1952}.)~
Thus, the main source of a positive potential discharged from the
surface of the cortex at stimulation of the surface of the cortex
consists of neuronic elements located at a depth of 1.3-1.5 ~~~
i. e. neuronic elements of cortical layers Y and VI. The fact that
the threshold of provocation of the positive potential is least
-at the position of the tip of the stimulating microelectrode at this
depth, on the other hand, testifies to this, Zt~~is greatest when
the `stimulating electrode is~found on the surface of the cortex
(Burns and Grafetein, 1952).
.~ 2. While stimulation of the motor region of the corte$ causes
negative biopotentials, contraction of the corresponding ,muscles does
~~not set in. Movements arise only xhen stimulation of the cortex
begins to cause positive potentials, contraction of the muscles
-setting in then the positive potentials diecheirged?from the surface
of the motor region of the cortex reach a certain definite.msgnitude.
Thereby, the group of-impulses of excitation. in the muscle (?Adrian,
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?
-130-
X936} corresponds to each positive i`luctuatien.in the cortex. At
the time the Positive potential is discharged from the surface oi'
the Cortez discharges of very quick impulses of larger amplitude
are discharged from the depths of the Cortez by a microelectrode.
These discharges are registered only xh,en the tip of the electrode
is at a depth of 1.3-1.5 ~?, i.e. in the region of the main source
of the positive potentials in the region where the bodies of the
lar er pyramids of layer Y are round (Burns and arafstein, 152).
g
These discharges, as already said, never arose at the time of a
ne~tive surface potential. Thus, the Positive potential registered
from the surface of 'the Cortez is connected With ezcitation of the
pyramidal neurons of the deep layers of the Cortez.
3? Positive response spreads Without decrement at a r.~ate of
0.6-0.15 m. .per second ~(Adrisn, 1936; Burnes 1951). During narcosis
.it spreads for a distance of up to 7.5 mm.' On the basis of the
spread trithout decrement, the conclusion is made that the spread
of positive potentials is linkad. With transmission of excitation
into the deep layers of the Cortez from neuron to neuron through
the synapses (Adrian, 1936)? The spread of the positive potential
3s avoided by incision, of the Cortez to a depth of 1.25 min. (Burns =
and Grafstein, 1952}. According to Burns, neurons of the deep
layers for.,~.a netxork consisting of "self-excitation" nerve orbits. ' .
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-131-
The minimal length. of these nerve orbits 3n his opinion, equals 2 ama.
. (Footnote: In a 1951 paper Burns gives a graphic depiction of this
netxork." In the illustration of the Burns and a~afstein article '
(1952) the elements of the netxork are 'presented in the~form of ce11s
xith "offshoots; Hos~rever,. the depiction given there of the connections
of the neurons is senseless Prom the point of viex of generally knotitn
neurological data: the offshoots of the neurons establish synaptic
connections betxeen one another i.e. the axon of one neuron with
the axons of other neurons the dendrites of one neuron with the
dendrites of other neurons. Finally, in the 1955 xoxk Burns supports
some of his theoretical ideas on the activity of the network of
nerve elements of the cortex by model experiments smith "titration
neurons" (:}.}
Origin. of positive potentials arising during stimulation of
the surface of the corte$. On the basis of a number of facts cited
above it is possible to consider demonstrated tliat the positive
fluctuations discharged from the surface of the cortex during
stimulation of its surface are connected xith,ezcitation of the
neuronic elements of the deep layers of the cortex., On the basis '
of eleatrophysiological and histological facts knorin at the present '
time it is possible to explain first the arising of positive.
potentials during~eacitation of the elements of the deep layers
and, secondly, it is possible to explain in Mhat We-y during stimulation
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-132-
of the surface of the cortex excitation of the elements of the deep
layers arises: ,
During clarification of the arising of the positive potential
discharged from the surface of the cortex it is possible to use
the same reasoning as for clarification of the arising of a positive
potential discharged from the depths of the cortex at activation of
the surface layers of the cortex, i. e. it is necessary to think
that iihen regional excitation, a negative potential, arises in the
bodies of the pyramidal neurons, then the correspond3.ng top dendrites
of these pyramids must~be polarized in a positive fashion. This is
virtua7.ly q~served too and this is directly shown by,Burns's
experiments. As already said, at sinking the discharge electrode
into the cortex to a depth of 0.1+ zan. and lower, a negative potentialU_
is registered (the same electrode discharges a positive?potential
when on the surface): Finally, it is knoKn that at direct stimulation
of the neuronic elements~of the deep layers (by means of a needle
electrode inserted. deep into the Cortez) from the surface~of the
Cortex positive fluctuations of potential are discharged (Adrian _
1936; Burns and. t~rafstein, 1952) .
Thus, the positive potential discharged from the surface of
the cortex expresses a positive polarization of the top dendrites
of the pyramidal neuron>~, stipulated by regioinal excitation of the
deeply situated parts of these neurons; probably of their cellular
bodies for the most part.
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-133-
During very intense stimulations of the cortical surface the
loops of electrical current can ahax a direct stimulating action on
the neuronic elements. of the deep layers and. cause their excitation.
Hoxever, during the conditions o~ stimulation xhich xere~used'in
my experiments, as alreac'~y said, repeatedly, primarily the fibers of layer
I Were excited. Excitation oi' layer I fibers can stipulate excitation
of deep layers by neurons of layer I, on xhich collaterals of layer I
fibers end. Since the descending axons of the (modified) star pyramids
of layer II discharge collaterals into layers III, Y, and VI and certain
neurons of layer IT have an axon terminating around the bodies of the
pyramidal neurons of layer III., then consequently at excitation of
these neurons activation of the deep layers should occur. Tf the
neurons of layer II With horizontal,azon (Fig. 26 - 2) are eac3ted,
the.collaterals of xhich terminate in many star pyramids of layer IT,
then this can evidently ~leacl to ezcitation of a Whole coniplea .of the
latter and to most intense "impulaation" into the deep layers of the
Cortez.
The~.folloxing facts obtained by Burns and Grafstein (1952)
speak in favor of this that exeitation of the neurons of the deep
layers and the arising of the positive potential can. proceed and
occur as a result of the excitation of the fibers of layer I. i+Ihen
the intensity of stimulation of the cortical surface~xas threshold
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in the sense of the provocation of a positive potential at a certain
distance from the region of stimulation, then surface-most. section'
of the cortex around the stimulating electrodes, which stopped the
spread of the negative potential,'inhibited the arising of the
goaitiv~e potential too. During intense stimulations of the ,surface
' of the cortex the positive potential spread even after intersection
(again the depth of the section, as already stated, did not reach
1.25 mm. ), but the latent period of its arising in a remote part
after surface section of the cortex eras lengthened several times.
Thus, excitation of the fibers of layer I can stipt;late the arising
of a positive potential. By means of the fibers of layer I
excitation of the deep elements of the cortex in a part remote
From the region of stimulation can proceed more quickly than When
the elements of this part are activated as a result of the successive
spread of the,ezeitation through the neuronic elements of the'deep
layers of. the cortex. ~ .
Thus, Stith stimulations of the cortical surface moderate in
intensity e~ccitation?oi; the elements of the deep layers occurs through
the fibers of layer I that are first to be excited. ~ ' ,
According to Burns (?1x51}, the negative potential arising,
immediately in response to stimulation is the reason Sor the arising
of a positive potential. When the negative potential, reaches a?certain
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excitation embrecesa other neurons c-~ the deep layers. Eccles (1951)
through the axon o~ the pyramidal neuron and its collaterals,'the
through a top dendxite~-ta the body of the?pyramidal neuron. Spreading
bocomes the source of a~diecharge of impulses which spread downward
critical magnitude, namely 30-35~ of its maximal amplitudes then it
thinks this the most likely explanation off' the mechanism oi' the arising
of positive potentials. Chang (1951) also thinks that the positive
potential arises when the impulses of the top dendrites spread to
other parts o~ the pyramidal neurons.
Thus, with such integration the local potential oi' dendrites of
the pyramids is considered as a source of the excitation of the pyramidal
neuron. We, with this point o~ view,_run into the diametrically opposite
.one which is developed in the present work and according to which
regional excitation of the dendrites is not the source of the excitation ,_
oi' the corresponding neuron. ~ -_
Adrian came to the conclusion that the arising.of the positive
potentials 'being considered is the result of the faot that 'the bodies
of the pyramidal cells are excited and that their 'dendrites are at this
time, in an inactive state (Adrian,,i938). However, it is impossible
to allege that at_ electrical stimtiilation of the sux~ace of the corte$
elements of the deep layers, particularly of the~body of the pyramids,
were selectively a=cited. 2t must. be thought that in this ea~ae too,
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the activity of the deep layers is dominant, and it moat be thought
that the potential being registered from the surface of the cortex is
the result of a negative potential and a positive potential. At
stimulation of the cortical surface, oxing to the spread of excitation
through the system of fibers of lsyar I, the top dendrites of a certain
xhen the positive potential ie registered from the surface, elements -
of both deep and surface layered are round in an active state, however --r_
number of pyramidal neurons of the point of the corit~* being discharged
.~: .
come into the regional excitation. HoMever, at excitation of the
fibers of layer I excitation can also occur of the deep layers through
the star and other neurons of layer II. As a result of this, the deep-
lying parts of the pyramidal neurons, of their bodies, can enter into
a state of regional eaci+.,ation. If, for simplicity, one pyramid neuron
is taken, then a regional?eacitation 3.n the summit dendrite arises ?'
3.n. it under the influence of iiupulses from the 'first source under a
certain number of synaptic endings-of the fibers of layer I. If at
thin tame ezcitation from a second sour~:e o~ a greater number of -
synapses occurs for the?body of the neuron being considered, then a
.more intensive regional excitation arises there and the negative
dendritec potential rill be masked by a positive polarization of the
dendrite, stipulateii by the negative potential of the body of the
pyramidal, neuron. On thG' other hand, 'the negative,-potential too,
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? discharged from the surface of this cortez, should not arrays testify
to the isolated activation of .the elements of the surface layers:
regional excitation of the dendrites can mask regional ezcitation of
the bodies of the corresponding neurons. Hence, logically it folloKa
that, Frith more or less identical ezcitation of the surface and: deep
layers, from the surface of th,e cortex as a result of an algebraic
'summation of potentials identical in intensity and opposite in sign
there can generally be registered a certain electrical potential.
.During deep nareoais the sign of the potential. discharged from the
surface of the cortex can actually testify,to the activation of the
surface layers (during stimulation of the surface of the cortex) or
of the deep layers (at stimulation of the afferent fibers --see
Chapter IV). This is connected xith the fact that during deep
narcosis activitlr 3s limited by thole elements on'Nhxch i~pulses
from the fibers of layer I that are stimulated or the afferent
impulses act directly. ~In these elements regional excitation arises,
and the reaction texmine~tes~in this. At light 'narcosis xhen the
excitability of the neurons is relatively high subsequent exaltation
of the neurons ocaurs,.as xell. as transmission of the ezcitation by
numerous elements in the various layers of the cortez and, as ke
see itiarther on~~in different paxts of the cortex. Certainly an
analya3.s ot,the bioelectrical potentials being, registered from the
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surface of the ccrtex becomes in connection with this much more
complex. ?
In connection with what has been said above, certain recordings
of bioelectrical.potent~.als wiU. be considered below,
We have seen 'that at deep placement of the diechai~ge electrode
below layer TI the negative potential arising iimnediately in response
to stimulation changes its sign: the negative potential is recorded
from the surface, the positive potential from the depths. As for
the supplementary negative potential, as Chang (1,951.) ascertained
its sign does not change at deeper placement of the electrode, '11ais
is seen in recordings C and D of Fig, 15. A supplementary negative
potential expresses regional excitation of the top dendrites arising
under ?the effect of 3.mpulses from the neurons of layer II that are
excited. However, as we have seen,,at excitation of the neurons of
layer II a transfer of 3.mpulsea occurs to elements not only of the surface
but also. of. the deep layers of the cortex, as a result of?which the
discharge electrode found in the deep layers discharges a negative
potential of the excited ~uronic.elements with Which it'comee in contact.
Thus, under the influence of iaspulses from the fibers of layer 1;. an
isolated activation arises of the elements. of the surface layers. At
excitation of the intermed,i,ate neurons of .layer IT activation ,occurs
of the elements both of the surface and of the deep lsyeri~ of the cortex..
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~ pig. 30 are presented recordings interesting 'to analyze.
With a stimulation intensity of 36 v-. (threshold 3?v.) shocks of
stimulation at a rhythm of?8 Per second caused double negative
potentials that set in without an appreciable latent period (osc.
A). At switching to a stimulation frequency of ~0 per second each
shock of stimulation been to provoke a negative potential of
considerably lesser amplitude than at infrequent stimulations. The
second negative fluctuation Mss especially reduced. After several
seconds of stimulation the effects attenuated still more. At
switching to a frequency of stimulation of 8 per second the stimulation
shocks began to provoke the same effects as prior to tetanizatinn
{osc. B). With the intensity of the stimulation at 30 v. the stimulation
shocks at a rhythm of 8 Per second caused effects considerably different
from the effects off' stimulation at 16 v. {osc. C): insignificant
negative deflection. axone even prior to its completion d m3.~.l,isecond.s
after the mpment,of stimulation, and a pa~rerful negative potential
set in with additional fluctuations in Sts descending part. Thus,
the impression is created {if the initial 'first insignificant fluctua-
tion is mistaken for an expression of polarization from the intense
electrical stimulation) that at energetic stimulation an effect arises
wi1;b. a greater latent period. _' However~~ there are no bases to cons3.der
the initial deflection as a Whole an artefact. It is necessary to
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consider it a highly attenu4ted negative potential, Nhich at 16 v.
reached a considerably greater amplitude. It is possible to explain
activation of the elenrnts of the deep layers tperhaps because of
this phPnomenoii by the admission that energetic stimulation causes
the~fact that the current directly ogciies not only the fibers of
layer T but also 'the cells of 7.ayer TT). The positive potential
arising at activation of the deep elements almost removes the negative
potential xhich the elements of the surface layers develop. The
results of experimentation x3th a change-over of the frequency of
stimulation to ~+0 per second speak in favor of the accuracy of such
a hypothesis. After 13 shocks of stimulation purely positive potentials
of lox a~litude and length begun to arise. After sxitching again
to infrequent stimulations the effects gradually became such as they
xere prior to tetanization.~ Tt is possible to observe the. change-over
from purely positive initial fluctuations to.3nsignificant negative
initial fluctuations (osa. D, ~).
{7,egei~7, to Fig. 30, teatpage 7~: Arising of~ positive potentials
in connection xith intensification and increase of frequency of stimula-
tion of the cortea.~ Cat No. 27; June 7; 1950. Rembutal. Stimulating
eledtrodes and the discharge electrode are placed on the gyrus
supraaylvius. Distance betti!een discharge electrode-and stimulating
electrodest = 3 mm. A ~- intensity of~stimulation 16 v., frequency in
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-l~l-
the beginning at 8 per'second, then 40 per second. B -end of one-
second stimulation Mith Yrequency of ~0 per eecond and shift to a
frequency of 8 per second. C -intensity of stimulation 30 v.;
frequency in the beginning at _8 pcr eecond, then 40 per second. D -
end of one-second stimulation irl.th a frequency of ~0 per second and
a shift to a frequency of 8 per second. E -continuation of recording
D. )
(Legend to Fig. 31, teatpage 7g: "Conversion" of positive
potentials into negative in connection W1.th prolonged stimulation of
the cortex. Cat No. 58, Aov. 21, 1953? Booster xith more constant
tame. Stimulating and discharge electrodes are placed on the gyros
suprasylvius. Bipolar discharge: one discharging electrode is
found at a distance of 5 mm~, the second at a d~.stance of 15 imn. from
the stimulating electrodes. The intensity o~ stimulation 30 v.
Frequency of .stimulation about 5 per second._ A -beginning 'of
stimulation. B - 0.7 second after A. C -effect of et3.mulation
after prolonged stimulation of the brain.) .
In vscillogram A of Fig. 31 is presented the effect of the
beginning of stimulation of the surface of the cortex' at a rhythm, of
5 per second. After the' artefact 'of stimulation a negative potential.
arose which vas quickly brazen and a positive deflection of greater
amplitude developed. As 'a result of prolonged stimulation the
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positive potentials ceased arising, and the stimulation began to
?cause only negative potentials {osc. C). It is characteristic
that the latter now had greater amplitude than When the co>~lez
positive potentials arose after them.. It is evident that activation
o~ the deep layers of the eortez t~askmd the activation of the elements
of the surface layers.
Thus, We have encountered cotnplea bioelectrieal phenomena.
Bach recording requires special analysis, and in the conclusions
to Mhich the analysis leads there sometimes remains touch of the
hypothetical.
11?. Contribution to the Question of the Spread oi'
Activity Through the Cerebral Cortez
BelaW a number ofl recordings Will be considered that Mere
obtained ;in experiments with stimulation o~ the cortex and registration
of the biopotentialB, Which Were made on aniimis under very light
narcosis. These data compel. one to recognize that the position,
thanks to Which the negative potentials that arise at direct stimulation
o~ the Cortez spread xith decrement for troderate distances, is in need
of mayor correctiv'is.
.. {Legend to, Fig. 32, tertpage 76: Distribution o~ activity
through the cerebral Cortez from the point stimulated. Cat No. 27,
June 7, 195(3. RelatirGly shallot nembutal narcosis. Stimulating
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electrodes (P) are placed on the anterior pole of the gyros
suprasylvius. In egperimenta A-D the potentials are discharged
simultaneously from point El {upper curves). at a distance of 3 mm.
from P and from point E2 {loMer curves) at a distance of 13 gyn.
from ?P. A - effect of stimulation during an intensity of stimuli
~of 16 v. and a frequency of 10 per second. B - aftereffect. C -
beginning frequency of stimulation 10 per aecond.~ then the frequency
changes to 50 per second. D - intensity of stimulation 30 v.,
frequency 10 per second. In experiment E the second discharge
electrode E2 is placed on the posterior pole of the same gyros.
Distance of P ~ E2 = 21 mm.; frequency of stimulation 10 per
seconds intensity - 16 v.)
The recordings of Fig. 32, A - D~ xere obtained in the following
xay. On the gyros suprasylvius Were placed: the stimulating pair
of electrodes {P) andJ at a distance of 3 and 13 mm, from them,
the discharge electrodes (E1 and ~}. The threshold of provocation
of the negative potential at point E1 equaled 3 v. Tn order for
the negative potential to arise at E2 the intensity of stimulation
necessary eras 10 v. With, 16 v. at point E2 considerable potentials
arose but of ~+ times .lesser amplitude than at point E1 (osc. A~). , At
point I+~ the negative potentials arose xith an insignificant period
of latency. At point F,2 it eras x3.th a latent period of 10-11 milliseconds
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xhich assumes a rate of spread of about 1.5 m, per second. ,
"Spontaneous" negative potentials arose at both points
simultaneously (osc. B).
Thus, as a result of the stimulation of one point of the
gyrua suprasylvius activation occurs of the top dendrites of the
pyramid neurons over a ride territory of this convolution.
(Legend to Fig. 33, teZtpage 77: Spread of activity
through the cerebral aortea from the point being stimulated.
Cat Fo. 36, Jan. 2, 1957. The potentials are discharged simultaneously
from-the middle part of the gyr. suprasylvius (E1, upper curves} and
from the gyr. sigmoideus post. (T2, loKer curves). The first pair
of stimulating electrodes (P1) is placed on the anterior pole of gyr.
suprasylvius, the second pair (P2) on the posterior pole of this
convolution (see schema).- The distance P2 E2~ 30 mm. A - "spontaneous"
activity, Band C - stimulation through Pl. B - effect of the 20th
shock at a frequency of 2 per second. and an intensity of 12 v. C -
4intenaity of stimulation 25 v.; at f3xst the effect of one shock, then
a stimulation of a frequency of 10 per second is applied (attention
is~draxn to the fact that a single stimulation xae applied at the time
of the "spontaneous" slox f'~uctuation in gyr. supraeylvius). D - effect
of stimulation through P2.)
Attention is called to the-fact that xith a frequency of
stimulation of 50 per second at a remote point potentials ceased to
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arise in response to shocks of stimulation and at the mpst proximal
point for each shock of stimulation a negative potential arose ,
(osc. C),?i.e. the impression M+ns-areated that at a stimulation
frequency of 50 per second transmission of excitation at point E2
ceased.
At stimulation of the anterior and middle parts of the gyros
suprasylvius negative potentials ariae~in the Posterior gytvs
on the surface of the gyros suprasylvius? The first discharge
28, 1950. The stimulating esnd?2 discharging electrodes are placed
the cerebral cortex from the Point stimulated. Cat Fo. 29, June
(Legend to Fig. 3~, tsxtpage 78: Spread of activity through
potentials in the gyros aignpideus (Fig. 33)?
pole of the gyrua suprasglvius cannot lead to the arising of bio-
sigmoideus. In the same prepare~tion stimulation of the posterior
' of stimulation. B - intensity of stimulation 20 v., frequency 10 _
A - intens'itg of stimulation 30 v:, frequency 10 per second, beginning
simultaneously from points El (upper curves) and E2 (lower curves).
_~., i, _..,.' ~.w.,,.., +~,. ai~ttnulgtinrL electrodes. ' The biopotentials dj,BC}]Arge
electrode .(E1) is at.a distance of 3 mm., the second. (E2) at a distance
of. stimul,e~tion 30 v. ~ ~'requeney 10 per? second; at t3.mde ?of exposure
Experiment ,E xaa carried .out prior to euper3.menta A - D; intensity
per second. C -frequency 20?per second. D - 100 per second.
the?direction of the stimulating current tires changed {attention is
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called to the direction of the artefact of stimulation).)
With verg light narcosis (Fig. 3~) the activity begins to
spread from the point being stimulated not only to greater distances
but also without appreciable decrement: the amplitude of the potentials
at a remote point can be even greater than nearby (osc. A and B).
Furthermore, coYaple$ effects arises the character of t~hich shows that,
together irlth impulses from fibers of layer I bg direct activation of
the top dendrites additional activation of them occurs from the
intermediate cortical neurons, the various coasplexes of Which are
included in the activity at a different tines. A small positive
fluctuation precedes the negative potential at point F2. However,
this i8 evidently an expression of polarization, since this fluctuation
disappears at change of direction of the stimulating current, whereas
the character of the negative potential is not changed (osc. F}. .
. - 6gmetimes duet one shock of stimulation causes prolonged
rhythmical aftereffect. In the .aftereffect the activity spreads
through the Cortez for a greater distance. Zn the eaperiment~ the
recordings of Which are presented in Fig. 35, `the shock of stimulation
applied to the surface~of the anterior pole of the gyrue ~suprasylvius
caused no bioelactricai reaction at point T2 (lg mm, from the place
of 'stimulation), an.,energetic ttro~phase potential, (osc. B) having
been provoked at point El (~ nae, from, the place of stimulation}. In
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-147-
the aftereffect the .~actiVity gradually' took hold of th3.s remote '
point (ose;Band C). .
(Legend to Fig: 35, teztpage 79s $prend of?activity through
the cerebral cortex?froai the point stimulated. Cat No. 21, May.10~
1950.- The stimulating pair of electrodes and 2 discharge electrodes
~rere placed on the surface o3' the gyrus suprasylvius. The first
discharge electrode (El) t+ae at a distance of ~ mm. and the second
(E2) xas at a distance of 10 rmt. from the stimulating electrodes.
The biopotentials discharged simultaneously from point. El upper
curves and point E2 (lower cuxwes}.
- "spontaneous activity".
B -effect of one shock of stimulation; intensity of it 30 v.;
length of stimulating stimulus 0.5 millisecond. C -continuation of
B recording.)
It is possible to think that at'the point,of the cortex
stimulated the cortical neurons excited by the stimulation'rhythmically?
continued to be excited and evidently the number. of neurons excited
gradually increased on the strength of summation.
At stimulation of the cortical surface at a rhythm of 10 per
second a bioelectri.cal reaction at a remote point can set in after
prolonged stimulation and;?then xhen?the stimulation?is not stopped it
" '' ~ ~,
can continue to ?be intensified (~'ig: 36, A and B). Certainly the
spreading?of the activity occur's"in tYiese conditions because of the
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ezcitation of an entirely greater number of, cortical association
neurons. It is characteristic that ~rhen in the experiment being
considered pokerful negative potentials began to be registered from
a remote point, then the effect at the nearast point became"more
complex toot additional negative fluctuations appeared (oac. B).
(Legend to Fig. 36, teztpnge 80: Spread of activity through
the cerebral cortex from the point stipulated. Cat Igo. 29 {i. e.
the same preparation as for ~'ig. 3~). The electrodes xere placed
on the gyrus suprasylvius, but they xere all shifted frontward.
P-El= ~- nnn;; P-F2= l~? mm. The potentials Mere discharged from
point El (upper curves) and point T2 (loxer curves). A -intensity
of stimulation 30 v., frequency 10 per second. B -after, l0 seconds
of stimu7.,ation. C -frequency of stimulation xas' changed from LO
t'o 50 per second:) .
? At increase of frequency of stimulation up to 50 per second
(osc. C~ the transmission of eacitatian shafted to remote point E2,
and at the proximal point E1 tYie potentials"right after the first
shocks of frequent stimulation changed their sign, xhich assumes
intena~e ezcitation of the elements of the deep layers of the Cortez.
Attention is. attracted to the fact that Xhen, as a result csf
prolonged stimulations at a"remote point of the Cortez slox negative
biopotentials arises than there is no~-appreciable difference in the
laTent periods of the arising of slots potentials at the proximal
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(~, ~) and ~~te (1~F mm. ~ points. Thus, the spread of egei~ation
can proceed at a very great x'a'te?
Evidently at prolonged stimulation certain cortical neurons are
excited, the axons of xhich proceed for greater distances and end
mainly in the dendritic surface layers of the co~tea. The excitability
of these neurons rises in such measure that, in response to stimulation,
they are immediately excited and, if it is aBSUmed the axons of these
neurons conduct the excitation at a higher rate, then it is possible
to explain tha absence of appreciable differences in the latent periods
of the arising of bioeleatrical effects at points E1 and E2.
The bioelectrical potentials at stimulation of the gyros
suprasylvius are registered, as already said, .in the gynrua sigmoideus.
Fags. 33 and 37, A (~xpper curves) illustratt~ this. Hoxever, at
stimulation~of the gyros suprasylvius considerable biopotentials;can
be registered also from the gyros ectosylvius (Fig.. 37, A, lower
curves). According to the morphological data of Bekhterav, this ''
spread of excitation from the gyrus'auprasylvius to the gyros
?ectosylvius must proceed through the fibers in the upper part of
Layer T, xhich serially connect the gyri lying parallel in a. line.
A peculiar reaction is ob$erped at th~poaterior pole of the
gyros suprasylvius at stimulation of the middle or anterior parts
of this grtas . ' from the surface of the posterior part of this gyros
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positive fluctuations of a bioeleetrieal potential are discharged ?
'the same gyros at a distance of ~? mm. from the point stimulated (upper
electrodes on the gyros suprasylvius; potentials are discharged from
frequency 10 per second. Al - courBe 1 second after A. B - stimulating
stimulation, excitation occurs of tha fibers that terminate in the
posterior part of the gyrus mainly in the deep layers of the cortex.
(~gend to Fig. 37, teatpage 81: Spread of activity through
the cerebral tortes from the point stimulated. Cat fto. 27, June
7, 1950. A - Stimulating electrodes are placed in the anterior part
of the gyr. suprasylvius; the potentials are discharged from the
~a sigmaideus post. (uppex curve) and from the gyr. ectosylvius
(loW6r curve}. 3,'he intensity of the stimulation xas 30 v., the
(Fig. 32, ~; see also Fig. 38, C). Evidently, as a result of the ~.~
curve) 'and? ~fxom the point of the gyros suprasyl`v3.us ? of the opposite
Intensity of stimulation 30 v., frequency 10 per se,chnd:}
As Danil:evskii ascertained, stimulat3'on of any point of one
hemisphere leads to the arising of a biopotential at a sy~nnetrical
point of the opposite hemisphere. According to Chang's data (1x53),
the part of ?the cortex activated in the opposite hemisphere is. no
more than ~F mm . in area. In Fag. 37, B (loxer curves) are shotin
hemisphere symmetrical to that?~hich?Xa.s stimulated (lo;aer curve).
that stimulated. Reese characteristic?"callosal affects" (Cur-ti.s,
the-effects in the opposite hemisphere at a point sym?etrical 'to
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. .. ~ - -~
A - on the gyr. ectasylvius, its anterior pole; B - on the gyr._
ectosylvius, its .posterior pole; C - on th~osterior Bole of th.e gyr.
190) are tiro-phase potentials similar to those that arise at peripheral
stimulations, i. e. after the positive phase ,a negative folloxs. Fig.
38 shoxs that the negative phase cannot arise, and in such cases the
"collosal effect" is expressed. only by a positive fluctuation.
(Legend to 1E'ig. 38, textpage 82: Activity spread, from point
stimulated, through the cerebral cortex. Cat No. 20,.Apri1 28,1950.
In all the experiments onQ and the.aarde point of the anterior pole
of the gyr. aupmeylvius is stimulated; the intensity of the stimulation
is 25 v.; the duration of 'rhe irritating stimulus is 0.5 miLtisecond.
The first discharge electrode (El) is placed on the gyr. suprasylvius
at a distance of 7 mm. from the stimulating electrodes (P); 3n all '
oscillograms the lower curve consists of potentials from E1. 7~e
second discharge electrode is placed on different parts of the'corte$:
suprasylvius; D - on the gyr.. suprasylvius of the opposite hemisphere
,at a place symmetrical to the place of~stimulation; E.-'on the poaterfor~
pole of the gyr. supraaylvius of the opposite side; F - on the. posterior
pole of the gyr. eetoay~.vius of the opposite side.)
At relatively~light~narcosis considerable positive potentials '
arise in response'todecond discharge electrode E2?xas set up. F -scheme of
placement o! eleetrodes. G - biopotentiels are discharged simultaneously
from point Ex (upper curve} and?from point E2 (lower curve); 15 seconds
from the start of tetania stimuli~tion at ~0 per second, 30 v. (Roitbak,
19530 ?) ?
'Fig. ~?2 ~illus;~rates this phenomenon. In this e~eperiment the
stimulating electrodes and discharge electrode were placed on the gyros
suprasylvius. The separate shocks of stimulation provoked a negative
slow potential with an amplitude o! approzizmtely 0.3 miuiv. At the
R
moment indicated by the arrow, t~0 s{ 7 7 { secaa~ds alter application -oi' a
single shock o! stimulation, the frequency o! stimulation ~s a7~changed
for 40'per second (osc. A}. Altar the initial effect, the negative ,
potential, .each shock o! atimtilation began to produce a Weak-f50-60 ?
micorov.)?positive fluctuation; alter several seconds of stimulation
?there positive fluctuations albrost dwindled to nothing. Then during
prolonged tetanization there suddenly arose~alaw negative fluctuations.
o! relatively great as~litude { 0, ~? nilliv.? } rl~rtha~ically following. one
another. Which proceeded not? according ~to the r2~rthm o! stimulation but
according to a !ar make infrequent .rby-tha~:~ et first 14 per ?~ second,
then 12 per seconds and altGr?several'mort.aecoaada o! stimulation 10 ?
-? o
per. "second .(osc. 8-D). 'At cessation o! ~stiaulation:ths rhytl~ical
electrical. -activitp'~ teas. brokenl_ i. e.. the , drising o~ ?it ~-as causally
connected '`iith".cerebral ~itiiaulation. The' phenomenon described 'teas
1
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reproduced Further on the preparation in question scores'of times,
Thus, it is possible to say o~ the~txb phases of tetanization
of the sorter: .in the first quick abatement of effects end depression
of the so-called "spontaneous" electrical activity are observed,'in
the second a most.energ?tic rhythmical electrical' activity arises.
Belo~r are indicated the conditions for the arising of a given
rhythmical electrical activity and certain of its characteristics.
'l. The animal should be either xithout narcosis or under very
light narcosis (active re`ilezes~to tactile stimulations, liberating
movements).
2. The stimulating. shock should be of a certaiaa minival
intensity; during a lesser intensity of stimulation the rhythmical=
electrical activity does not arise although activation of the surface
layers of the cortex can occur. ~ ~ '
3. The frequency of stimulation should?be no lrnter than a
certain limit: on'lightly narcotized animals?no,l~er than 25 per
second; but on non-narcotized a~imeil.a rhythmical electricallactiv3ty
can arise even at a frequency of stimulation of 3 per second.
~. The greater the intensity of stimulation and its frequency,
the shorter the latent period of the arising of rhythmical electrical
activity, 'which can become' equal to 2 sec., in al.l.
S: ,During uninterrupted stimulation the rhythmical activity ?
gradually abates and ceases a't approx'ti~tely 60 seconds' ?after the
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`moment of its arising. .
~6.'It 3s'possible to provoke rhythatcal electrical activity
iii. any peirt" of the cortex; on the other hand, it can be provoked at
a given point of the cortex: ~duritig ~ istimul.ation of various points of
the cortex"and:~not:-pf~~any one certain point,
7, For-repeated obtaining of the phenomenon it is necessary to
observe intervals Of 3 miII. or more bets~een the tetanic atimulationr~.
8. At interruption of stimulation that has provoked ri~ythmical
electrical activity an aftereffect is often observed (~'ig. ~); the
.electrical effects in the aftereffect are of an entirely different
character. During repeated tetanizatioaa of the cortex `rith interval$
of 3-~+ miautes the aftereffects become even more and more prolonged.
9. El~ythmical electrical activlty~ if it arises in the orator
area of'the cortex, can be attended?by~movenants arising long before
they set in. The arising of ?the focus oY'rbrythmice~l. aativi,ty in
other regions. of the cortex is ~aueil.ly' not attended by any motor or
vegetative redctions.
10: A.~ phenomenon of a similar sort is not observ'ed~ in
experiments on~spinal cord either dur3bg protracted direct electrical.
stiaulationa of the gray matter or during protracted stimulations
-of the ~ nerv~ea (8eritov and, Roitbak; 18;50) ~ -
After the eiper3.iaent considered. (?ig, ~?2i osc. A~3) ion gyrua
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suprasylvius the second discharge electrode E2 xas placed 10 imn.
distant from 'the stimulating. electrod~ss; the ,discharge electrode
both from ~ and E2 bioelectrical potentials xere~discharged (the
electrodes). .During tetanic stimulation (~0 per second) at first
T, eras left at t2be ?first place (6= mm. distant from the stimulating
effects'fram E2 having been?altered so~exhat,;by..~polarization):
at E, and E? dwindled a].moat to nothing. Then during prolonged
After several seconds of,tetanization the electrical effects both
being considered arises in a limited focus of ~the,cortez and.cnnaot
Were=?diseharged (oac. a). Thus, the rhythatieal electrical activity
familiar to us~ arose; front E2 at this tine no additional. effects
rhgthaically follrnring one another, and the phenomenon,already
stimulation from?~Rl slox negative fluctuations begun ~Cs::be discharged,
spread through. the cortex even ~rithin the 1ir+;t~ of one convolution.
Usual7.y rhythmical electrical activity is not registered at-e distance
greater than 10 mgt. from the.stinwlating electrodes (on narcotized
animis }.. ~ '
Rhythmical electrical activity arising'during,prolonged
tetanization.of the cortez sari Bear a moat diverse character, but
electrodes Sts character ruins constant and. tens of?tinte in succession
for a? giv~cn preparation xith fisted. position, of the atiaulating and discharging
it is possible 'to ;observe .oas.oatyd-the sanrc sterotypic ,reaction.
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(Legend to ~'ig. ~?3, textpage 107t~Rhythmical electrical '
activity arising at tetan3.zation of the cortical surface. Cat lfo.
55; July 7,,1953? The stimulating electrodes and the discharge
electrode are placed on the surface of the gyros suprasylvius;
distance betxeen them 6 inn. Intensity a~ stiwlation 30 v. A
in the ,beginning frequency of stimulation about 5 per second;. at
r~~:
the end of~the oacillag~ram?frequency of stimulation about 1 per
second. Each recording after i-ecord3ng.A is an immediate continuation
E -end of-stimulation at 100 per second and -
of the preceding.
change-over to a frequency of atinulation of 5 per second: ?? The
long fluctuation s at a rhythm of about 30 per minute are evidently
governed by a respiratory pulaatian of the brain:} __
In, Fig. 43, where each recording is an immediate continuation
of the preceding, the course of the development of~rbythmical
electrical activity is seen. Tlie separate ahocks,of stimulation
provoked a negative potential lasting about .10,m3,lliseconds (i.e.
an. elementary dendritic potential arose}~ after xhich a long positive
potential follotred. (osc. A-) . At axitching ~ to a stimulation.-frequency
of 100 per aecoz~d. only ,the first ~-5. shocks provoked an affect ,
(negative potential); in the courae?of the folloxing three seconds
r
the stimulation renie;ined apparently?entirely inactive: only artefacts
`recorded: (oec: ,B).,;~~]~ezt -rhythaical. electrical
f stimulation kere
_
o
activity arose in the fart of ne$ative`~'fluctuations of potential.
. -The. aarplitude of the fluctue,tiona iu. the course, of the next -6 seconds
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of tetanization constantly incrensed; the frequency of the rhythm
gradually diminished in the courss of stimulation from 30 to?20 per
The phenomenon considered arises also during stimulation of .
the White matter of the corte=x i.e, during the action of the afferent
impulses on the cortex (Fig. ~+6). Neverth~leas, even during
~etanization of the cortical surface activation of its neuronic
elements proceeds by the "physiological route" and in~our experiment
conditions by impulses of excitation of the fibers of the first layer
of the cortex directly stimulated.
A theoretical analysis permits concluding that the rhythmical
activity is linked With the activity of other neuronic .elements than
those Which are implicated during infrequent stimulations or at the
beginning of tetanizstion. During infrequent and xeak stimulations'
exoitation in the system of?fibers of layer I, evidently also?at
participation of the neurone of layers :Y and II, extensively over-
flats through the cerebral cortex, Everywhere stipulating "the
arising of regional processes of excitation in the neuronic elements
of the surface, layers o~ the .come=. This f3.nds; its electrical
expression in the fact that during infrequent atimulationa of any
point of the cortex from any other point ofathe surface of the
hemiisphare negative fluctuations of potential era usually discharged.
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Rhythmical electrical activity is stipulated. certainly by
excitation of certain contpleaes of intracortical neurons, evidently
not efferent but neurons xith'short atoms xhich are dust as numerous
in the cortex. They must?be those completes of neurons on xhich
impulses from the nerve elements f3:rst excited (by direct stimulation
of the cortical surface} act to a subthreshold extent. During
prolonged tetanization heightening of their excitability occurs and,
xhen it reaches a certain critical magnitude, these neurons act that
possess, as seen, an extraordinary capacity for awmnation. Besides
an extraordinary capacity for summation, these cortical neurons, as
it is possible to conclude on the basis of the data already stated
are very susceptible to the effect of narcotics and are characterized
by quick fatiguability.
By using Aissl and Cabal's method for staining, xe.succeeded
'in catching the dine nor~hological changes of the neuronic elements
of the cortex in the region of the focus of rhythmical electrical
activity that is created by electrical stimulation of the cortical
surface (Cholokashvili and~Roitbak, 1.955}? Changes are observed in
the fibers of layer I (xhich,are restained and more intensively convoluted
than in the normal),, in~,the top~deridrites of the pyramids (xhich are
rough, ~ i. e. tba aoatour'
is' ~~aiwoth than o~rdinarT} and
in the bodies =02, the, neurons; =mainly a~`;cortical layers ~~zl $nd, TII
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(between the nucleus and the protoplasm of the cell a clear boundary
is torn, the I~is~l bodies protrude Morse more often tiny; vacuoles
are encountered). These structural changes, not residual imprints
of the pathological, axe evidently connected with the process of
excitation of the corresponding elements, Thus, the histological
data obtained fully agree titre the ideas developed on the mechanism
of activation of the come= during stimulation of its surface.
(legend to Fig. ~4, teztpage 109: Electrical activity of the
cortex at the time of its tetanic stimulation and in the aftereffect.
Cat No. 3$, Jan. g, 1951? 2 Paine of stimulating (P1 and P2) and 2
discharge electrodes (E1 and E~) are placed on the surface of the
gyros suprasylvius. The biopotentials are discharged from paint .E1
(upper curves) and from point E2 (loXer curves). A -electrical
activity 6 seconds after beginning of,stimulatiori through electrode
P2 with a frequency oP 50 per second,. 25 v. {P250). B -aftereffect;
section 1.5 seconds after cessation of P2 stimulation; C -after
~~
3 seconds, D - af`Cer 11 seconds; E -scheme of location of electrodes
With indication of distance betteen them .in mm. in ezperinrents A-D.
F -scheme of location`of electrodes in eaperimenta G and H, G !-
electrical activity.:. aeeonde af#,er the start of the combination. of
,. .
~, ,':. .
Pl stimu].atioas ;a~%,ftha rate of~w50 per second {P~So, 25 v.) and P2 at
a rhythm of 5Q per~~second (~P~~?- . ,.. 25 v. ~): H -the aftereffect subsequent
. _'? 50"
1 " ~~ ~ 2
to cessation of- P. -~ :+ P ~ stimulation ~ (8oitbak~ 1953x) ? )
J
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Why is the rhythmical electrical activity limited to certain
i'oci2 Why does'the'excitation spread not occur over the whole cerebral?
cortez? ~ridently another process, limiting it, exists side by aide
xith the excitation. Ezperirmnts, the recordings of ~thich are presented
stimulation of the cortez it is fitting to think?of an active localization
o?' ezcitation... in counterbalance to the action of the branchix.g currents.
However, this~ective localization can be ac~omplish~ed only by a braking ??
action." By the xay, electrical effects during local strychnine poisoning
of the cortez .~.s 7_imited strictly by the ple~ce of poisoning, and the
process of inhibition tiraa the, 'reason indicated for this phencrnon
of the cortex the rhythmical electrical activity that has arisen in.
a certain part of the cortez does not spread to a region several
mi113meters distant; hoxever, at csesation oi' the tetanization in the
ai'tereffect the activity spreads to this other region also. Tlius, at
time of tetanic stimmulation that has?provoked and maintained a focus
of rhythmical activity a process occurred that limited the spread of
this activity. Apparently this is a Making process. Ukhtomakii
(~1926~ had already come to the conclusion that "during electrical
in ~'ig. ~, give basis for such a conclusion. At time of tetanization ,~
(Beritov, 19~8~. Belox facts are-?presented that indicate the inhibition
not only limits the focus of .r2~yttimical~ activity but also gimmes it no
opportunity to dev+elop~to its 3'ull strength and.ens thia?activity
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The foll:oxing experiments rere set up t~'ith a combination of
stimulations of two points of the Cortez and with registration of
the electrical potentials wising. - -
The results of one such experiment are presented in Fig. ~5
(~teatpage 110: Bioelectrical phenomena at the focus of heightened
excitability created in the cerebral cortex. Cat No. 2~-, try 20,
1950.- The first pair of stimulating electrodes (P1) is established
at the posterior pole of the gyros suprasylvius, the second {p2)
at the anterior pole; the discharge electrode (E) is located in
the middle of the convolution. A -stimulation through electrodes
P1 at a rhythm of 9 per sec. (P g) end addition of stimulation
through electrodes P at a rhythm of 50 per sec, P2
- .. 2 ( 50); intensity
of stimulation 30 v. -B - insediata continuation of A. C -
continuation of :a combination of stimulations -Pl'9 + p250 12 seconds
after the moment of addition of P2~. D -cessation of P250 -
stimulation during uninterrup-tea stinculation by 'p19. g.._ 3 seconds
after cessation of combination of Stimulations,,- ~' - after a further
15 _seconds. . Q - after a furt2yer 10 seconds,; cessation of P19 '
stimulation. -H -scheme~of location of electrodes (Roitbak, 1953x):).
The following ~$ the set-up of- this axperlment. The first pair of -
stimulating electrodes (Pl) ryas 'located at .the. rear pole of the gyros
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suprasylvf.us, the second pair of stimulating electrodes (P2) jtas
established on the anterior pole of this convolution, around .the
sensory-motor region. The discharge electrode (8~) was located ml.ditay
'between the two stimulating pairs.
Stimulation through Pl at a rhythm of 9 per sec. (P19) provoked
at point F simple effect: in response to each shock of stimalatio~n
a negative fluctuation arose of small a~plitude, on the d,escendiag
limb of which there was a weakly ezpreased additional t~3:uctuation
(Fig. 1+5, osc. A). bus the P1 stimulation by itself' caused activation
of the dendritic plexus of the upper layers mainly under the effect
of ingiulses from the stimulated fibers of layer I. During prolonged
stimulation of the Pl point at a rhythm of 9 per ~eaond it ~s
possible to observe progressive reduction of the amplitude of the
biopotentiala, their character.not having altered:
After 20 shocks 'of P19 stimulation a tetanic stimulation'we.s
added through the P2 electrodes at .rhythm of 50 per second (P2~),
In the first moments of tetanization each shack of P2~ caused d
negative fluctuation. On the background of tb~.s effeat only Meek'
Ply stimulation was found, reflection ins hardly to be. observed (osa.
A). Such a picture was observed in_;,the~ crnase of several s~acmds of
2 y ,~`
tetanization, at which tine ~progresaive abatement of the P- '~~~~~ireeta.
. ~ ~ ._...
occurredd(oec; B}.
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but also in ,attenuation or falling out, of the effects of stimulation
not only in degressiou of the "ipontaneoua" electrical activity
Thus in?the first seconds oY teiranization around the point
of the cortex being stinnzlat~d inhibition develops which is expressed
5
Mhen the shocks of this stimulation readjusted to provoke their own
of other regions of the cortex. 'Several seconds after `P2 0 tetanization,
to nox: slox'negative potentials arise at Ply rhythm, at the rhythm
the effect that arose differs froa those ~-hich tre, have considered. up
direct effects energetic rhythnical. activity arose?(ose. C?). Hoxever,
of combined stimulation: land) in xysponse to the shocks of this
stimulation.
The offects xhich aro~ta in rssponae to P1? stimulation at the
t3.tm 'of P`~ tetanization differed characteristically from the usual
effects of P19 - at,?each shock of stimulation With a greater latent
period. (about 20%~ieecands) a slox ni~,ative potential of larger amplitude
;+ _' R-~ ~
set in; direct effect$ of Pl9 stimulation; which xere provaked~by this
stimulation, prior?~_to the combination of~stimulations, arose ncnr too,
but their ampltud~_ i~oeis: 'reduced. In other Morris, the effects stipulated
..~ ~ , w
by the activity oY the?eortical neurnnn Mere extraordinarily intensified.
~
.group of cortical asurons; at this tine the stimulation of another point
stimulation (P2~) the excitability is eztrenely'heightened.in a certain
~. ..
L
Thus, the sig~ni~icance of such,phenomena: as a result of tetanic
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of the cortez (Pl9) provokes their ezcitation.
At cessation of (P2~) tetanization of the Pl9 effects begin
to intensify (oac. D) and their growth occura?in the course of 0.5 .
seconds: ovident7.y at the time of P2~ tetanizati'on th,e process
of inhibition took place and?this inhibition had a prolonged ?
aftereffect. At P2~ cessation the Pl9 effects changed in character
-?,
too; they beeaae mAre prolongedt double and triple effects appeared,
and after the negative complez a considerable positive deviation
arose (oac. E-G} . Infrequent atintulattons of the Pl point for a
period of tens of seconds at cessation of the combination with the
tetanic stimulation of the P2 point continued provoking the complex
effects described. Eeut, these affects simplified abated and
ceased to be provoked. The P19 again provoked its direct effects
in the form of simple negative potentials that .set in with a
negl'~~ible latent period but considerably lesser amplitude than at
the beginning of the experiment prior to annexation of P2~; a ?
teat of 30-60 seconds eras ~sutficient for these effects iro ?~be restored
to thess initial magnitude. ?
Thus, elevated excitability of s?certain con~lez of ne~ons.
is prolonged a long tiae aiter?ceeaation of tetanic at3mulation.of
the cortex and cau be demanatrated at stimulation of another?point
of the cortex. located at :a considerable distance ~rom~ the point
'e.
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sub~e;ted to tetanization. (Footnote: Rosenblueth and. Cannon (192)
cite in their xork an eacperiment (on monkey) the results of ~ihich
amount to the-follo~-ing. Separate shocks of stimulation applied to
the raptor area of the cortex for a back pex {foot) provoked,certa3n
electrical effects in the motor area.for a front pax (hand). After
repeated tetanic stimulations of the motor area of the facial muscles
convulsive electrical activity arose that spread over a vast region
of the cortex, including the motor area for a front pax. Separate shocks
of stimulation provoked at the time of convulsive electrical activity
and xithin a certain time after its cessation intensified electrical
effects similar to the components of the convulsive. activity. Hoxever,
Rosenblueth and Cannons not having attached any special importance to
these facts, dad not subject them to analysis.)
In Fag. ~5 it is seen that infrequent stimulations (P19) in
consequence of union xith tetanic stimulation (P2~) begin to cause
nex eomplez elects xhich, as compared xith.the initial eflects~of
Pl9 stimulation, are completely aZtered,? such as xould occur if part '
of the cortex tWas 'poisoned ;by strychnine (fee Fig. ~45, ~ and Fib? 23~ B)?
On the other.hand~ infrequent shocks o! stimulation of another, often .
remote, part o! the cortez~ producing nex eFfacts and exciting neurons
found in~a state o~ heightened?excitability, produca direct ellects.o!
their oMn too. For insteEnee, in .F'ig., ~5i A, it is .seen that,.pridr to
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the combining of stimulations Pl9 and P2~ in response to each
shock of stimulation a negative potential ass registered, Which
arose after an artefact of st3mul:dtioni i. e. impulses of excitation
proceeding from point Pi act~.vated at the point o= discharge mainly
the synaptic ending's to the top dendrites, but they also reached
the. intracortical neurone_apperently oY 1ay~er II (see teztp. 65)
sometimes caii~ing~excitatiori of a certain small number of thew,
C ..
Which tics expressed in the appearance of a small "hump" on the
descending limb of the dendritec potential. When the focus of
rhythmical electrical activity Was linked With the tetanization
of point P2 in the discharge part of th,e cortex, then the shocks
of stimulation of P19 began to produce larger slam potent5~ale,that
set in With a latent period of about 20 milliseconds; but in the
latent period of. these effects after an artefact. of stimulation the
previous simple negative potentials arose (Fig. ~S,,C=G);~their
,amplitude Was apparently reduced~3n consequence~of the prolonged P2~
tetanization (co~gpare.Fig. 30, A and.B).
Hence, it ie passible to make the~~olloxng conclusion. .Tn
?the presence of a ~ocus~of heightened.ezcitebility 3.mpulses of.
excitation from extraneous sources are not deflected at this focus;
? . ~-
inpulaes of ezc3:tation during secondary stimulations proceed ;there
and by the same path~aya as Mhsn it .is not.a focua.oi' heightened
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be tw-ea..a s"~, a~ P~,~ ~ - st~afiioa ~, e3sctra~~ at a x~
i~ Fl~uischargr el,ectrod~e {F} p?.aced CFzi t1xE .szsrfzce oY ;~ brain.
th~st into the white attter mdter the cortex at .a distance o~ 10 ms.
placed an s~-Face o~ gprua sugraaylvius, second pair (P2, microelect odes}
fat Bo, 33s J~,Y 16, 19'j0. ~`irst pair of stian2ating electrodes (Pl}
sotn`ce o~ heightened excitability created is the cerebral cortex,
which these itgpulses proceed even prior to zhe creation of a focus
of heightened excitability, but they could at that ti*~e show only a
subthreshold eYfect on thew}: however, as before, they produce also
that initial bicelectrical reaction which is characteristic to them
in norffi1 conditions.
(Legend to Fig. ~6, textpage 113: Bioelectrical phrnosae~sa at
excitability. They thereby produce as intense bioelectrical reaction
of elements which are found in a state o~ heightened, excitability (to
el;~-o~.es at a ?r~t~[ of 'll ~~~}; the %hot~3ca cr: ~.~~~ ~ cry F2
?,~ per ~ (~~} a~ adaitfae o~ satian i~on~h.l'~
are is~icated ?~ arrays, ~ - s~ .~ the coa~ination cz?'
ate. ~~ of ~~ ~~:~ ~ -. i ~ ~ ~~ ~
~dita`teci ~ ,L~ar} ~.i~ ~,~~,,,~~, ~,~ `~ ~,~. F~
~` ~ s ~ - ~-.~ ~ ,~ ~~~ ( of ~~
~'~,. + P`~, ~t3o~a 3~ ~ at`t~r the aa~t cd' t~ a~r~~
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-21~#-
In Fig. f+6 the results are presented of a somewhat modified
ozperiment. The first pair of~tstimulating electrodes (Pl) xaa
plmeed on the surface oP the brain. At a distance of ~~ mm. from it
on the surface oi' the brain the discharge electrode (E) xas located.
TWO isolated micraelectrodes ses~rsd as second pair of stimulating
electrodes. They mere sunk, deep into the t~hite matter under the
cortex at a diatance.,of 6 ~. from the discharge electrode. Thus,
the discharge electrode.~s betxeen the electrodes that stimulated
the?surface of the brain and the electrodes that stimulated the
xhite matter.(aee Fig. ~6, H). Stimulation through P1 xith a
frequency of 10 per second (p110) produced negative fluctuations
of the biopoten~ial With an anq~litude of about 0.75 milliv. (osc.
C~ the. beginning}. At addition to P110 of a frequent tetanic
stimulation through. P? at 5U per second ~~r,.). easipTete inhibition
oecurredof the_effecte of Pi- g~3uulation (vac: C}. After 7 .
seconds of a combination.of~,the stimulations an energetic rhythmical
electrical activity~aroeie 'at ;the. rhythm of Pl (osc. D). ~ Thus, this
~stimulatiun ? "tied" its axn ~'r~tytY~i ~ onto the neuronic elements -of the
focus of heightened;ieact
' 2
ground v~ the tetanic~P ~ stimulation began ta?yield?complea.e~fects
of` a character completely different from those t~hich ~ere~ produced
liy it prior to' uuaai-;off stimulationd~';zamely the P 10 began to produce'
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-215-
positive fluctuations of potential, solitary and double. Thus, prior
to she combination of ,stimulations {P110 + PQ~) the Plla stimulation
xas not markedly reflected on certain nerve elements located, as xe
have a right to think, in the deep layers of the Cortez. As a result
of the union xith the tetanic stimulation of P~~, the P110 stimvl.ation
becomes capable of ezciting them not only at the time of P2~ tetanization,
but also at a ties long after its cessation (osc. E - G).
On the basis of the ezperiment considered With stinnalation of
the v+hite matter it is possible to conclude that the focus of rhythmical
electrical activity can be created by the action of afferent Impulses
that come to the Cortez. '
If the P110 stimulation (stimulation of the surface of the`brain)
stimulation of the xhite mutter 'was added at a rhythm of about l0 per
second (P29 or P 11), then depression-of the P110 effeots ~-as observed:
the negative fluctuations produced by stiaulation?aof the surface of
the brain abated, their degree ofabatement having been determined by
tIu time interval bet`teen shocks Pi and P2 (Fig. 46; osc. A and B);
at cessation of P~ sti~wlatiaun the-?Pl effects gradually increased
an~d._after a certain time reached ~the3r initial 'agnitude. ?
Thus, xe eacountsr eztraordiaary alterability an~d.nun~eraus
` J
phenomena. In the first place, stiaulati.on of a gi~nsn point of the
Cortez can produce diTrerent ef=ecta~ depending on the phase of its `
action (2 phases of .tetanization. o!'- the -Cortez). Ia the second
place,. the stimulation, of ' a gi~veri paint of the Cortez stipulates
L~~-
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different sftects depending on the f'requsncy' of stimulation:
For instance, in the case ~uat considered the stipulation through the
P2 electrodes at a rhyth~a of 11 per second produced only depreaaion~
of the erfects of P1 stimulation; stimulation through. P2 at a rhythm
of 50 per second in the second phase of tetainization stipulated
complete~~inversion of the effects of P1 stimulation. (This important
question tri 11 be. esamined again in a special tray..
(I,egend.tQ Fig: 47, teztpage 11~: Bioelectrical phenomena at
focus of heightened excitability created in the cerebral Cortez. Cat
~o. 3~, Oct. 24;~=1950. Stisulating electrodes and discharge electrode
are located on the surface of the gyrus suprasylvius. The first
discharge. electrode (B~} is found at a distance of ~ mm, th,e second
(S2) at a distance of 10 ~adt. Eros the 1~tiawlating electrodes. ~Bio-
potentials -are disc2~arged simultaneously from the Tsl point (uP1xr
curves) and from the Ts? point (loxer curves). A ~ beginning of
stimulation at a rhythm of 12 per second; intensity oY stimulation
3Q v. B -continuation of ati~aulatioa at a rhytt~a of 1~ per second.
and shift-over to a 'stimulation i'requericy,of 80 per second, C -after
3 sec. , , D -after 8 sec. , ~ -after lO sec. _, F - af'tisr ?~3 sec. oY
tminterrup_ted tetanic stimulation. ~ - achese of srrange~oent, of
stipulating and discharge electrodes (Boitbak, 1953a)~.^~)~. _
In the eperi3sents the recordings of rich are presented in
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Fig. ~7 the stimulating electrodes and 2 discharge electrodes~~~iare
placed on the gyros auprasylviua; the first discharge electrode ( )
_ ~.
at a distance of ~ mn~., the second (E2) at a distance of 10 nnu. from
the stimulating electrodes (~sse BYg. ~?7, G). At Hirst atimu].ation
M+ets applied at a frequency of 12 per second (osc. A). At po3.nt E
1
in rirsponse to each shock of stimulation double effects arose: after
the first negative fluctuation (1 milliv.} that lasted about 10
milliseconds, even prior to Sts con~letion, a second set in (0:8
milliv.), about ~?0 milliseconds in length. At point E2 double negative
fluctuations (0.19 and 0.3 milliv.) also arose; in the course of
stimulation these effects intensified somexhat. At shift3.ng the
frequency of stimulation to 80 per second (osc. 8) the effects in
E1 and E2?as early as after the first shocks of tetanic'stimulation
changed their sign aud'then quickly attenuated. 'After 3 seconds of
tetanization additional fluctuations began to arises owing?to '~hich
the curves acquired a.s+avy character (osc. .C).? After 8 seconds of ?
tetanization at both ,points of the cortex a rhythmical electrical '
activity arose: from 7~ positive fluctuations of considerable
amplitude ('up to 0.6 milliv.) xere discharged at a rhythm of about
25 per secon3; from Try negative .fl,uctuations { up ~o_ 0:35 milliv.) .
~-ere dia'charged at? the? same rhytl~a (;oac:~ .D). . On the 10th: second, of
tetaniration the rhythmical acti.vit~ ;lost,,,its reguLsr character ,,
(osc. E): On the 13th eecpnd.; at poi=it=~B~-'?e~ter regulicr intervals there
{ k ,~w
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begfin to arit~e groups of 3~~ positive fluctvatioas; at~point T2
in respect to each such group a single ueg~itive fluctuation o~
potential of great length (osc. f) arose. 'Phase electrical effects
set in at 2=3 t~.m~es a second, and such activity xas observed for
a period. of a furthersl5 seconds of tetsniiation.
' Thus the rbythmical electrical nativity that arose as a
result of tetanie stimulation of the cortez can be changed conaidsrab3.y
in its character in the course of prolonged tetanisation: each given
moment of tetanisation is distinguished from the preceding or the
subsequent one in the sense of '~,ha composition of the complez of
neurons 'being activated.
It has already been $aid that stimulation of a given point
of the Cortez can produce effects different in character depending
on the frequency of stimulation. The ezperim~ent dust considered is
a good .illustration of this.aapect. During stimulation of a given
paint of th,e cortez~at'a rhythm of 12 per second at point ~1 preeffiinent
activation of elements of the surface 3.ayers bf the cortex occur;
certe~in com~plezea 'of neurons of the deep layers are thereby ezaited~
hrnro~er long this stimulation lasts. Hceteverl stimulation (of the
sBae intensity) of the very-aaae point?oP the cortez.drnxs these nex
neuronic .cougilezes`into reaction during an increase o! its Yrequency
to k0-BJ per second. ~ ? .
furthermore, during tetRnic~atisulation.of the Cortez rhythmical
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activity arises xithin the Baits ~f a relatively large territory.
Moreover at di=ferent points of 'this region rhythmical activity can
have a di=Perent cbare-cter, Mhich assuares the participation in it of
neuronic,eleaents-of a different sort of origin. ~ the given case
(Fig. ~+7} local tetanic stiaulation of tha surface of the brain led
to the arising of rhythmical eiiects even at point Sl~~ xhich.is
found.at a distance of ~ mm. from the stimulating electrodes: and
at point ~~ at 10 mm. from 'the part stimulated. Hoxever, at
positives and at E2 nagative fluctuations of the electrical potential.
arose, In other xords~ at the center of the focus of rhythmical
activity ezcitation me~inly of 'the neurons of 'the deep l,ay+ers of the
cortex occurred; at the periphery excitation af' elements of the
surface layers predoai.nated (i. e. se-inly dendritic offshoots in
layers T and. TI). (Footnote: Tf relationships of such sort prove
regular] then inasmuch as activation. of the surface layers is
connected xith depression of the "spontaneous" electrical activity,
it xould be very tempting to ~-dmit that activation of the surface
layers of the cortex along the periphery of the focus of this activity
is the reason for restriction of the rhythmical activity. At that ?~
titre also it Mould, be, possible to cite these data as an electropbysiological
dampnstraticm of the follc~ing positiaa oi' Pavlov "The point of
concentration, af' stinaalatior~ to a care or less aztent i,-""`~~d
J~
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by a process of inhibition" (Ae4vlov, 1932).)?
At ezeuaix~ation of Fag. ~7 Me dMell~cl on the tact that as a
result of several-second tetanization {$0 per second) of the cortex'
at points ~ and ]f;2 complez rhythmical electrical activity arose.
At the 30th second of tetanisatioa the frequency of stimulation xaa
shitted to 12 per second (y`ig. 1!$, oac. A). (Legend to Fag. ~48,
teztpnge 117: Continuation of the ezperia~ents the recordings of
which mere presented in the prececl3ng illuatrati~on. A -niter 30
secanda of uninterrupted stimulation at s rhythm of 80 per second,
the frequency of stimulation in changed momentarily to 12 per second.
B -direct continuation of recording A. ~ -after 3 seconds, D -
after 6 seaonda, E -after 9 seconds, F -after 15 seconds of .
uninterrupted stimulation at a rhythm of 12 per ~eecond. After this
the frequency ofstimulation tras again shifted to 80 per second. G -
after 13'seavnds of tetanization the :Frequency of stimulation of 80
pcr second ~shitte? to 12~ per second.) Bight at the same rhythm of
stiauldt3on there begran to arise at point ~ positive_fluctuations.
(5o millibeconda) and at 'point a2 neyatiYe (80,millisecande) df
electrical potential, the amplituck o= Which equaled,+0.9 and ._0,`65
leilliv. Thus, .after ~tetanization ini~equent e:timulationa of the same
point of the~corte~c pTOduced at ?~ 'entirely distorted effects; eCs
regards ;the a=fects" , oP~point ,=2,? then ?an ~eitraordiitiarJ intensification
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occurred~~of a second negative fluatvation (co~are-Fig. ~7, A and
Fig. ~, A) ?
As seen from examination of ~`igs. ~7 and ~+8, infrequent stimula-
tions bf a given point of the cortex that impart change to the tetanic
stimulation and have'creaired a locus of r2~hmical electrical activity
produce in this ~~,ocus effects the same in character as there were at
the time or :tetanisation, i. e. infrequent shocks of stimulation excite
the same complexes of neurons as stipulate by their activity the
arising of rbrythm9.ca1 electrical activity, complexes which xere not
excited by infrequent shocks of stimulation prior to tetnnization,
Thus, elevated excitability of the neurons of our focus can be
demonstrated both during stimulation of other points of the cortei
(Fig.~4g~ and during stimulation of the came point of the corteaJ
the stimulation of which is stipulated by the_arising of this focus.
Finally, these phenomena are of one order. "
Attention is again drawn to Fig. li$ because at cessation of
tetanization the"effects of inf~equent?stimulations increased `during
the first second,. reacYiing amplitudes of -0.9 and +1' miLliv. (osc. B).
Progressive abatement of then beglen after 5 seconds, the dttenuation
~, .
oi' the positive fluctuations (effects at 31) haling proceeded Wore
a
quicklT than the negative (the effects nt T2}, and_aiter 9 seaond~i~
from the auaent of cessation oP stimulation from lCl neg~e~ti've fluctuations
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Were again discharged, i. e. the effects acquired the usual character,
and from B2 there xere again discharged n,eg~ative fluctuations considerably
intensified as compared to the normal (osc. F). Shortly after this the
frequency of'etimulation again xas changed over to 80 per second; as
a result of several-second tetanization, Weak rhythmical. activity arose
(osc. G); infrequent stinwL-tions, imparting frequent change, produced
extremely attenuated effects ordinary in~character (compare Fig. ~+8, G,
and 47, A). IIsuslly, as already said, repeated tetanic stimulations
of the cortex do not cause rhythmical electrical activity if the interval
between the stimulations is less than 3-~ minutes. Thus, in order to
obtain the Phenomena considered by us, rhythm3.ca1 electrical activity
of -certain elements. at tine of tetanization of the cortex and prcionged
elevation of their eacitabil:ity at cessation of tetanization, the part
of the cortex in quest'inn should be exhausted by previous. activity:
Experiments similex in nature are'presented.in the recordings
of Fig. ~+9 (~te~1~8e 119: Bioel.ectrical phenomena 'at a focus of
heightened ezcita~ility created in the cerebral cortex. Cat xo. 30',
July is 1950. The stimulating electrodes are thrust in under thy.
cortex in the .region of the posterior pole~of the gyros suprasylvius;
the~disch~+rge electrode is placed on the surface of this convolution
at a distance o~ 10 nm. from the stimnzla4ting electrodes. A -effect
of stimulation ~t ~a~,r2~ythm of 10 per second (~30 v..). B - 0.,8 sec.
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from the start of stimulation at a rhythm of 54 per second. C -
25 seconds from the start of atimtlation at a rhythm of 50~per
second and shift to a t~equency of stimulation df ~10 per sec. D -
0; 3 sec. after C. T~ .is 1 minute after D. ~' -effect of stimulation
at a rhythm of 10 per.sec. before poisoning, a -effect' of the
same, stimulation 17 minutes after local strychnine poisoning {1+~
solution) of the~cortez wader the discharge electrode.). In these
experiments the stimulating electrodes {microelectrodes~ Mere
driven into the gyros suprasylvius to the tihite matter; the discharge
electrode teas estabiishdd on the surface of the cortex at a distance
of 8.~mm. from the stimule~tiag pair. Shocks of et3.mulation at
inf5requent rhythm cauged'at the discharge point txo-phase fluctuations
of small. amplitude; at~ first a positive, then a negative fluctuation
arose (Fig. ~+9, onc..A).. Evidently activation of the cortex occurred
by means of fibers that enttered from the white matter; as knoxn,
afferent and ca116sa1 fibers terrii.zs~te mainly in cortical layers III
and IP. At arrival in the cortex of a volley of eacitation?impulses
along these Fibers first of all the elements of these layers are
eze3,ted~ ~bieh is expressed in. the fact that at discharge from the
surface of the correspoa~ding part of the cortex a positive fluctuation
of potential ~.a regist:red, after ~hicht when tha functional state
o~ the, cortex: is goody ~a negative fluctuation folloits:
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?With a shift over to frequent tetanic~stimulation (osc. B),
at the rbythm of atimulatian small positive fluctuations began to
arise. After several seconds of?tetanizstion acomplication of
effect set in: at irregular rhythm sloe fluctuations of greater
amplitude bean to nriBe (osc. C). With transition after this to
infreq~ient stimulations, it leis observed that the latter began to
cause intense complex bioelectrical effects (osc. D). These
effects are not intensified initial effects (i. e. effects Kh3.eh
Mere caused before tetanization of the white m9-tter). On the
contrary: the initial complex (+-) abates, but after it xl.th a
considerable latent period first a positive, then a most intense
ne`t additional potentials ceased to.axise, and each shock of
,negative potential arise. After many seconds of stimulation these
stimulation caused an effect the same in character as at the very
Intense.additione~l potentials, which arose after tetanization,
beginning of the experiment, only highly attenuated.
set in with a greater latent period,(of the order of 20 mil.liseconds)J
t-hich indicates participation of cortical. neurons intermediate in
their origin.
If in the preceding case (~'ig. 118) the activity of the neX
.elements as a trhole maa3ced the initial bioelectrical effect, since
the new elearents? v*re e~ccite3 directly in response to 'stimulation, then
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in the case in question the n~ex elements xere drain into the reaction
after the end of the initial bioelectrical reaction that set is
imosediately in response to stimulation.
In the recordings dust cited~3t is likexise Been that the so-
called "spontaneous" slots potentials that arise during tetanization
are considerably smaller 3.n amplitude than the slow additional
potentials arising in response to shocks of infrequent stimulation,
incessantly changing; they are not only smaller, but they are also
variable in amplitude and length.
As kaolin, strychnine has a characteristic c.~-pacity for
increasing the excitability of neuronic elements. Consequently,
it Mould be possible to ezpect that during local strychnine poisoning
of the Cortez phenomena, xould arise like those considered above,
trhich mere treated as a consequence of heightened_ezeitability of.
cortical neurons.
Some t3.iae after the ezperiments described. ~xith tetanization
of tY~e Cortez ,(Fig: ~?9, A-D), the area under ~ the discharge electrode
~s poisoned frith l~r ~atrychnine ? solution. Im~rdiately .befa~e
poisoning, stimulation of 'the Mhite setter at a rhythm of 10. per'
second produced the effecti~already described abo~v~e, consisting of
a brief positive fluctuatiou,e, after ?i~hich.'a ne~ti~-~s tollo~ed~ of
~ss~ll. anXplituds, but greater ?length~ soietiaes. complicated, by' addi~ionnT.
"humps" (oi~c:' ~'}? .After poieaning~,. the ;sale stia~uhation began to
produce nex ,effects: ~ ~-e.tter- =ths,, initial'.firat: coiplez, attsauste3.
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~226-
in at~l.itude.~ a positive .fluctuation arose ':. a ?~.eitent_ period of
20-25 mill'~secondsy after tihich a most energez~: ~twgative potential
~oiloMed (osc. (i)., Thus as a result oY strychninization of the?
dircharge point of the eortez during st3,nulstioa eitscts arose like
those which been to arise in response to this stisulation after
tetanizetion of seversleseconds (.corrpsre osc. D end a}. A similarity
is discovered also in such a detail as that in both, cases additional
energetic potentials arias in response not to each shock of stimulation
but to each. second or third shock,
Since 3t .is arell,knoam that a heightening of the excitability
~of the intermediate neurana lies at the base of the change of
bioelectrical effects under the action of the strychnine then. the
facts cited can sirve es demoastratiori of the tkct that the phenomena ,
being considered; connected With prolongai tetanic~sti,mulation of the
'cortez~, go~anerxt heightening of the excitability in. the nex additional
co~Iezes of the intracortical neurons, xhich usue~]_.ly are. not excited .
in response to .infrequent chocks of stimulation.
On tha basis iaf the facts dust considered ~ it .is possible to
_ - ~ ~.
conclude that the arising oi' cocgplez sfi'ects near in chmractar niter
tetanisation is connectad~~at least-in the case in question, xith
change o~ the state of the neurons. the region t'raa rhich those.
etYects mere. recorded and not in the region. of the .ppplication of
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stipulation, because the xhite as~tter ~s stimulated and, secondly,
an essentially siailar result xas obtained at local strychnine~poisonfng.
in the discharge region. As already acid, strychnine convulsive effects
axe not limited strictly to the region. of `poisoning.
As already said, during combine:tion of stimulation of txo points
of the cortex {one point is stimulated,tetanically, the other xith
relatively infrequent shocks) rhythmical electrical activity arises,
rind the rhythm frequency is determined by the fre-quency of the second
infrequent stimulation: thin stipulation "imposes" its rhythm on the
neuronic elements of the focus o~ heightened excitability.
(T.egenrl to ~'ig. 50, teztpage 121: Bioelectrical phenomena at
the source o~ heightened excitability created ia.th~e cerebral cortex.
Cat Ao..38, Jan'- 9,~1951?~ Tko.Pairs of stimulating'{Pl and P2) and
2 discharge {~ ans. T2} electrodes'xere placed on the surface of the
gyros suprasylvi'ua (see scheme). The biopotentials are discharged -
front point Tl (upper curves} and from. point F2 {loxer.curves). A -
Stipulation through ;electrodes P1 at a rhythm of 10 per second (~'10}
.and ann~ea-tion of~ stimulation through el~ctroder P~ at a rhythm.of
2 The intensity .of stimulation of Pl and F2 is
~50 'per second. _(P~~~):
1
. 25 v. B ~- length,, of combi.natiou of .stipulation P 10 + P~~ .9 seconds
efter' moment . of~: anneaaeitioi~ of P2 ~ C ~- stippulation. through electrodess
- z ~, .
P2 at a rhythm, oP ~0:-per second (P2~): The 11th second -after beg3.nni~sg
f, tetanization. ~ ~= end ~of tetaai~iitiori.-~ty P2~ and beginri3.ng -of
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-228-
stimulation by P110' moment o! application o! first-shock through
electrodes Y1?ia indicated by arrow. R?- scheae?of arrangement of
electrodes ? (Roitbak,, 1950.?)
The set-up of the ezperimenta, the reer~rdings of ph3.ch are
presented in Fig. 54, uas Wore cot~lez than thore described up to
now: here reg~.stratioas were sods of the biopotentials of txo
points o! the cortez during combination. of stimulations o! txo
points of the Cortez (sig. 50, E). Stimulation of the anterior
pole of the gyros supraaylvius at a frequency of 10 per second
(p 10) causes at point B1 (5.5 met. frost P1) negative fluctuations
of potential and at point S2 (r19.5 sn. lrom Pl, the posterior pile
of the convolution) positive 3'luctuations o! potential.?'At the
T
combining o! the tetanic atimtlation of the aiddle part of the gyros
suprasylvius xith a frequency of 50 per second (F`~0) the P110
stimulation becorea for a long time inactive, as it tirere (osc'. A).
3e~neral seconds alter .combining the stisialationa r2>3rthmi:cal electrical
activity arises at point ~ and.=2. Front El positive fluctuations
are registered and, Eros ~ negative fluctuations (?oac. B). Thus .
xe a?ain are caulronted `-ith !acts indicative that at the periphery
of a focus o! intense rhythmical activitT.o! the elements of the deep
la~nslcs of the Cortez edsentisl; aictiwation of the surlbce.la~nera occurs.
The :-rhythm o:C; th+e ne~tive .lluetuations at ~ axed o!? the, positive at
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El is determined by P1 stimulation: fluctuations arise in response
to shocks of this stimulation; Eton time to time double effects ~(osc. B)
arise to the shocks of ~l,stimulation.
? of the same neuronic elements as. are excited at the time of tetaniza~n.
5
of a different character (osc. C): at uninterrupted stimulation groups
oY ~-~ positive fluctuations arise periodically separated from one
another by 1~5 of a second pauses.
At cessation of the tetanic stimulation that produced rhythm3,ca1
electrical activity there often occurs a mare or less prolonged after-
effect. The bioWlectrical potentials at the time of the aftereffect
are usually similar in character to the bioelectrical potentials at
the time of tetanic stimulation (osc. D; see also Big. ~). It is
possible to think that the aftereffect is stipulated by the activity
P2
C stimulation,iri itself causes rhythmical electrical activity
? Tf at cessation of tetanization of a given point Qf the Gomez,
at the time of the aftereffect a-relatively infrequent stimulation is
applied to another point of the cortex, then the aftereffect can be
broken and effects at the rhythm of the'stipulation applied.(osc.'D)
begin to arise. (l~'ootnote: Aftereffects at .cessation of tetanization
laated~ten seconds and had the same character as in the recordings'
of ~'ig. ~~ xhich ~+ere ~~de on the: same prepexation.) Thus additional
stimulation can "control:" the-activityof the neuronic elements at?~the
focus of heightened excitability, determining the rhythm of~their
excitation not .only dur~.ng its coab3nation ~r3.th tetanic=> stimulation
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that created this focua~ but also at the time of the aftereffeet~
xhen the rhythm of the arising bioelectrical potentials is determines.
by influences not alxays yielding to calculation.
(yegens,`to l~ig. 51, tertpage ~: Bioelectrical phenomena at
focus of heightened ezcitability created in the cerebral Cortez.
lion-narcotized-rabbit. lLarch 10, 1951 Breathes through cannula in
trachea. Through an opening in the bone and in the Jura mater 2 pairs
of electrodes were Placed on the surface of the cortex: in the motor
and optical regions. The biopotentials are discharged from the raptor
regioh; stimulation is applied fo the optical region. The intensity
of stimulation is 30 v. A -stimulation at a rhythm of 5 per second.
$ - aftereffect at cessation of stimulation. C -repeated stimulation
at a rY~y'ti"hm of 5 Per second, at the time of the aftereffect.
immediate continuation of recording C. $ - e~~ffect after cess?tion
of stimulation.)
The phenomenon described is 'observed too in e~eriments on non-
.narcotized anime~ls. Fig. 51 serves as illustration for this position
in xhich are Presented recordings obtained in'ezperiments on non-
narcotized tracheotodized Zebbit. Th+e discharge Ix-ir of electrodes
xas set up on the'-rotor area of the cortezi the atinulatiag electrode
on the optical axes. _ Bach shock of ~~t3au7-ation at d,rb3-~, pr 5 par
seconRT produced in, the nator area a ?d,ffinits electrical effect ~ (osc. A
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-231-
at this time no motor or vegetative reactions arose. At cessation
of stimulation. a prolonged aftereffect Mss ,observed, i.n the ~ forn- of
slox potentials at a regular rhythm .of about 7 per second (oac. B).
Stimulation, xhen it vas applied at. the time of the aftereffect,
brake it off: effects began to arise at the rhythm of stimulation
(oac. C and D); at cessation of stimulation the aftereffect described
above again occurred (oac. E). '
At combination of stimulations of tvo points of the cortea a
more intense rhythmical electrical activity usually arises than at
stimulation of one of these points. This also refers to cases xhon
tetanic stimulation is applied to the first point 'but the second
point is stimulated by comparatively infrequent electrical shocks
'(Fig. j2, B and G). It is possible to think that during combination
?f P110 + P~50.a greater number of the neuronic elements of a given
complex is implicated. in reaction than in the .case of isolated P25
.. ~
stimulation. '.Q~us, additional P1'10 stimulation not only stipulates
the ezcifiation rhythm of neuranB of the dominant focu"s but also
evidently increases the number of focal elements excited.?
. If at combination of P110 + P2~ stimulations rhythmical electrical
activityarises, then at cessation of P2~ stimulation the PliQ?atimulation ~??
continues to ezcite ueueilly,.for a period af, tans of ~second.s .the neuronic
.;. ?
elements of the focus-of"heightened ezcitability that hna arisen. If
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at combination of P11O + P~5O stimulations it does not lead to the
arising o! rhythmical electrical activity, then at cessation o! P25o
,atimuiation the P11O stimulation produces its ovn.ordinary elects
as it did prior to union.xith the tetaniic stimulation. If at
combination o! P11O + P250 a rhythtical electrical nctivity arises
sad the combination o! stiaulation lasts tens of seconds before the
disappearance o! rhythmical electrical acti~rity, then at cessation
o! P stimulation the P11O sti~aalation produces its oxn usual
50
effects, only greatly attenuated in con~arison xith those Mhieh it
proQOked prior to union o! the stimulations. Thus, infrequent ~'10
stimulation at combination~xith the tel''snic P25O stimulation does
not produce ezcitation of a given complez of neurons so long as
their ezeitability has not yet reached a certain critical magnitude
at-xhich they are capable of being rhythmically ezcited under the
.action of impulses .of any origin that arriv8 in the cortex. or i1'
this high ezcitability o! theirs. has already fallen because of
ezhauation. ~~
{Legend to Fig. 52,'textpage 12~: Biaelectrical phenomena at
a focus of heightened e~eitability~created'in~cerebral?cortez: Oat
Ko. 37, Jan. 7, 1951. The.lirst pair .of stimulatiog electrodes (Pl)
xas placed on the-rear pole o! the gyrus,suprasylvius, the second.
(P2} ~ on the anterior. ~ The ;dischsrge electrode {~) MSS .pl,aoed at+ the
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middle of the convolution. A -stimulation through Pl electrodes
at a rhythm of 10 per second (P110) and combination of etimulatiori
through electrodes P~ at a r2~ythm'of 3a PeT second (P~~). The
intensity of stimulation ass 25 sr. B -continuation of combination
of stimulations 10 seconds after moment of annexation of P 50. C -
cessation of P2~? stimulation during uninterrupted P110 stimulation.
several seconds after recording D. F -effect of P1 stimulation
10 seconds interruption in its action; stimulation star interrupted
D -continuation of recording C. E -effect of P1 stimulation after
P`C~ tetanization and beginning of P110 stimulation. Z ~- scheme of
stimulation; 72th second from start of tetanization. H -end of
after 20 seconds of interruption in its activity. G - P250
arrangement of electrodes-(l~oitbak~ 1953a}.}
Zn preparation Ao. 37; as a result of tens of repeated,
experiments ~(stith 5-minute inters-als betxeen eaper3.ments),' it seas
possible to lie persue-ded that the infrequent P'10 stimulation, at
interruption of P2__ tetanization, continued fora period of ~0-60'
seconds to produce nev effects the same i.n character as those that
xhen~..3t proceeded in "an, isolates stay st ces$ati'on of? F2~ t+as. broken
fluctuations of biopotential {?ig. 52, D). .If P 10 stimulation
arose at the time ,of tha,combination.of P110 + X50' positive'
off ?.for? 10=15 seconds, then at ?repeated ~srtitching on this; ,etimulat3.on
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ceased to provoke nex effects, Mhich,? it it Mere not ~?terrupted in
its actian~ it Would continue to produce for 20-30 seconds more. In
other ~tords, because of the change described in ?the. course of the
ezperiment~ P~'10 stimulatioh last the capacity acquired by it as
the result of comb{n~ xith tetanic stimulation,? the capacity. to
? neuronic elemeata of tlae deep layers of ~? coY`~=? The X1]:0
excite
nox produced Sts usual effects,, ne6~ti~ fluctuations of potential,
someMhat abated as compaxed xith those Mhich here provoked prior
to a combination of stimulations (Fig. 52~ E). '1'hua~ infrequent
stimulation of the cortex sustains a state of heightened excitability
in the focus that had arisen during combination of this stimulation
xith frequent i~etanic stimulation of another po~,nt of the cortex.
On the above-mentioned 'basis it~is remarkable that 1Y +
j t 1 310. at 3nterruptio~i
infrequent etimoulntions.are applied to point P {P )
of tetanization of point P2 (P2~) which eentioued prior to the
arising of a r?~lrthaii:al electrical activity mAizinr~l in intensity,
then it is possible to obtain? those `phenomena tl~hich are observed as,
the result of a combination of P, 10 + ~~ stiffiulations? ~ - .
eZperi,nsnt 52, , H f the P110 stinioulation Mss applied for 284 nilliseconiis
after cessation ?of .P2 tetanic, stimulation. The ~10 stimilation
__.._ ;.~ .~..~ .ff'~cta~as commared xith those xhich ~it ceiused~, after
ca'b3,nation xith ~~ stimul.,ntion; :the .first shock caused a negative
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(compare Fig. 52,H and C) xas lacking in these effects or ra.s slightly .
ezpressed.
fluctuation; the last shocks caused positive fluctuations,~but these
effects in an~litude and duration considerably yield to the ePfeets
xhich P110 caused after eombination~xith P250 and,~to xhich attention
should be turned in these .effects additional positive fluctuation
suprasylvius 2 pairs of stimulating electrodes xere placed (P1 and.
xhich xere presented in Fig. ~5. On the surface of the gyros
No. 24, xay 20, 1950. Continuation of ezperiments the recordings of
the focus of heightened a=citability created in cerebral.corte=. Cat
(Legend to sig. 53,, teitpage 126: Bioelectrical phenomena in
P ) and betvean them a diecharare electrode B free gahem~l_ A ..P1
gt3mulation and annemtion~of P ,~? stimulation. B -cessation of
a
mu
50 _ 9 + 50 ~ ?~'
P2 Btimulattion alter 1~+ seconds of union of P1 P sti
l
ti
C - 15 seconds after B; cessation of Pl9 stimulation.. D -end of
15-second ~ ~? stimulation and anne~oa,tinn of P1? stimulation. T -
continuation. o! D'. F - several seconds after E, t~ -scheme of
arrangement of electrodes.)
of Fig. ~5, analysed_ in detail, As e: result of the -combination of
1 ~~
stimulationsyP 10 +-P25o, P110 nt interruption of P250 began to-caus.e
The e:cperiaent, the recordings of xhich are ,presented in Fig.
53; A-C, is a repetition of the e~c,~eriment illustrated by the recordings
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Declassified in Part -Sanitized Copy Approved for Release 2013/04/23 :CIA-RDP81-010438001900230005-7
-~36-
new complex effects. After 5 minutes an ezperiment was set up the
recordings of xh3ch are presented in Fig. 53, D F. Zbtanic stimulation
of a second point of the Cortez (P2~) was continued up to the arising
of a rhythmicp~l electrical activity me~zimal in intensity; stimulation
of the first point (P110} was begun 0.5 sec. after cessation of P2~
tetanization {Fig. 53, D}. In spite of the fact that this stimwlation
was applied at the time of the aftereffect, it caused no ner complez
effects (compare 53, ]7; E, F and 53, B and C}~
Thus, it is possible to conclude that the fact of union, of
coincidence at the time of thsstimulation$ of two points of the
corte$, has importance in the sense of determining the character of
the bioelectrical effects which one of the stimulations being combined
provokes after the .cessation of 'the other. Thus, the effect of direct
electrical. stimulation of a given point of the cortex depends on the
preceding history of stimulation in'a more complez sense than has.
been admitted up to nrn-: the effect of stimulation depends not Qnly
on the previous stimulation of a.gi~ren point of'the Cortez and not
only on the previous stiiialation of other~pointa of the Cortez
('Pvedenakii, 1897), but also'on the fact of $ previous coincidence
3.n time of stimulation. af- a given poizit of the Cortez by stimulation
of ~ other point of the Cortez.
Finally, in Fig. 54 arc preieentecl recordings of an eicperiment
the set-up of 'which ?traei the tollaMing. Txo pairs of ~timiilating
_ _: ~ ,
electrodes xere eetabli~hed, on the gyrus.aupraaylvius at,a distance
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Declassified in Part -Sanitized Copy Approved for Release 2013/04/23 :CIA-RDP81-010438001900230005-7
of 11 mm. feast one another, and the discharge electrode xas betxeen
then. Stiaulation?of point Pl at a rhyth~e o~?8 per second (P18)
during a stimulation intensity of 4 v. did not cause appreciable
bioelectrical effects at the point being discharged, E (ogc.~ A).
At anueaation of the stimulation of goint~P2 at?a rhythm o! 100
per sec. (1'2i0 gradually intensifying rhythmical activity quickly
arose at the rhythm o! Yl.atimulation-(oac. B).
At cessation o! tetanisation the alternate slat fluctuation
had a considerably-larger as~litude thaw at the time of tetanization
(osc.~C). Furthermore,, the slat i'luctuations proceeded at a far
more infrequent rhytha, but the effects that arose here connected
iri.th Plg stimulation: each consplez effect use a grog of fluctuations
at a rhythm of?about 50 per aecwod and the ala- fluctuation of
potential arose ~.u reapozise to each second shock o! Pl$ stimulation
(osc. C and .D} . -Alter several? seconds ?the effects xex'e simplified:
at a given part being,discharged~ alight electz~ical effects which can
each Pla shock caused a double positi~e~lluctuation (oac. E). Alter
1 ~ ~ ?
several more seconds the.P 8 stipulation began-to cause such effects
as prior to union o! atiaulatiotta (osc. ~'). -
Thus,- infrequent stimulation o! paint Pl o! the c~ortez ct~uaed,
be considered an? ezpression -ably ~o!- polari:ration; afterward at this
? ~ 2 ~ ~?
point, as ? the result -.of P ~- . ~~~ va~.a