Neurophysiological analysis of postnatal development of corticostriate connections in rabbits

Evoked potentials were recorded in the caudate nucleus of adult rabbits and young rabbits aged 2–30 days in response to stimulation of the ipsilateral motor cortex. The response of the caudate nucleus in the adult rabbit consisted of a positive-negative complex with latent period of 3–5 msec. Maximal amplitude of the response was observed in the dorsorostral region of the nucleus. As the recording electrode was inserted deeper, the amplitude of the response gradually decreased but without reversal of its polarity. Responses of the caudate nucleus to stimulation of the motor cortex were recorded as early as on the 3rd day after birth. These responses were indistinguishable in configuration from responses of the nucleus of adult rabbits. Their latent period was about 10 msec. Between the 16th and 20th day after birth the latent period of the response decreased considerably — from 9 to 5 msec, and by the 30th day of life it had reached its definitive value. With age the amplitude of the response increased but the threshold of stimulation decreased, The results indicate early functional maturation of connections of the motor cortex with the caudate nucleus and they agree with the results of morphological investigations of the structural development of the afferent systems of this nucleus.Brain Institute, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 14, No. 3, pp. 284–289, May–June, 1982.     

Corticofugal influences on postsynaptic processes in rubrospinal neurons in the cat brain

Composite and unitary EPSPs of red nucleus neurons evoked by stimulation of the sensomotor and association parietal cortex and nucleus interpositus of the cerebellum were studied in acute experiments on cats anesthetized with pentobarbital. A monosynaptic connection was shown to exist between not only the sensomotor, but also the association cortex, and rubrospinal neurons, in which unitary EPSPs appeared during stimulation of the association cortex after a latent period of 1.5–2.7 msec, with a peak rise time of 1.1–3.1 msec and an amplitude of 0.22–0.65 mV. Analysis of the temporal characteristics of the unitary EPSP suggested that synapses formed by fibers from the association cortex occupy a position nearer the soma than synapses formed by axons of sensomotor cortical cells.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 16, No. 1, pp. 67–74, January–February, 1984.     

Effect of stimulation of the caudate nucleus on activity of neurons of the globus pallidus

Activity of neurons of the globus pallidus was recorded extracellularly during stimulation of the caudate nucleus. It is demonstrated that background activity (BA) of most neurons of the globus pallidus is depressed under these conditions, which is regarded as a manifestation of inhibition of the investigated neurons. The period of BA depression varied in different cells from 60 to 500 msec. In some cases this period was preceded by emergence of an action potential with a latent period of 10–20 msec. In addition to inhibition of the activity of globus pallidus neurons during stimulation of the caudate nucleus, it was possible to record evoked responses of the given neurons in the form of group discharges with a latent period of 18–40 msec and single action potentials with a latent period of 50–100 msec. The neurons that reacted with a shorter latent period were localized at the lateral limit of the globus pallidus, whereas neurons with other kinds of responses were distributed in the globus pallidus comparatively evenly.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 1, No. 2, pp. 202–209, September–October, 1969.     

Neuronal responses of the reticular and anterior ventral thalamic nuclei to stimulation of the thalamic ventrolateral nucleus and motor cortex

Responses of 137 neurons of the rostral pole of the reticular and anterior ventral thalamic nuclei to electrical stimulation of the ventrolateral nucleus and motor cortex were studied in 17 cats immobilized with D-tubocurarine. The number of neurons responding antidromically to stimulation of the ventrolateral nucleus was 10.5% of all cells tested (latent period of response 0.7–3.0 msec), whereas to stimulation of the motor cortex it was 11.0% (latent period of response 0.4–4.0 msec). Neurons with a dividing axon, one branch of which terminated in the thalamic ventrolateral nuclei, the other in the motor cortex, were found. Orthodromic excitation was observed in 78.9% of neurons tested during stimulation of the ventrolateral nucleus and in 52.5% of neurons during stimulation of the motor cortex. Altogether 55.6% of cells responded to stimulation of the ventrolateral nucleus with a discharge of 3 to 20 action potentials with a frequency of 130–350 Hz. Similar discharges in response to stimulation of the motor cortex were observed in 30.5% of neurons tested. An inhibitory response was recorded in only 6.8% of cells. Convergence of influences from the thalamic ventrolateral nucleus and motor cortex was observed in 55.7% of neurons. The corticofugal influence of the motor cortex on responses arising in these cells to testing stimulation of the ventrolateral nucleus could be either inhibitory or facilitatory.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 10, No. 5, pp. 460–468, September–October, 1978.     

Reflection of temporal parameters of an optical stimulus in unitary responses of the sensomotor and visual cortex in cats

Unit activity in the visual (area 17) and sensomotor (areas 4 and 6) cortex in response to an optical stimulus up to 1000 msec in duration was investigated by extracellular recording in acute experiments on cats anesthetized with chloralose (70 mg/kg body weight). Comparative analysis of the types of unitary responses and the durations of the intervals of functional changes showed that: 1) The number of neurons generating on-off responses was about 25% in the visual cortex and 100% in the sensomotor cortex; 2) the intervals of functional changes of the neurons were equal in length to the time intervals of on-off discharges; 3) together with a single time range (200–500 msec), for each area studied specific ranges also exist: from 0 to 200 msec for the visual cortex and from 500 msec and more for the sensomotor cortex; 4) the latent period of after-discharge is equal to the duration of the intervals of functional changes. The results were analyzed from the standpoint of reflection of temporal parameters of optical stimuli by neurons of the sensomotor cortex.A. A. Zhdanov Leningrad State University. Translated from Neirofiziologiya, Vol. 7, No. 4, pp. 365–371, July–August, 1975.     

Responses of cat cerebellar cortical neurons to stimulation of the caudate nucleus,globus pallidus,and substantia nigra

Stimulation of the head of the caudate nucleus in cats anesthetized with chloralose and pentobarbital evoked spike responses of the Purkinje cells and other cerebellar cortical neurons in the paramedian lobes, lobulus simplex, and the tuber of the vermis. Phasic responses in the form of simple discharges (on account of activation of the neurons through mossy fibers) appeared mainly after a latent period of 5–12 and 14–20 msec; the latent period of responses consisting of complex discharges (on account of activation of Purkinje cells through climbing fibers) was 5–6, 9–22 msec, or more. Depending on the latent period, the spike responses differed in their rhythm of generation. In response to stimulation of the caudate nucleus with a frequency of 4–6/sec recruiting responses were found. An inhibitory pause was an invariable component of the tonic responses. During stimulation of the globus pallidus responses of the same types (phasic and tonic) appeared as during stimulation of the caudate nucleus, but they differed in the distribution of the neurons by latent period of spike responses. The minimal latent period was 4 msec. Recruiting also was observed during repetitive stimulation of the globus pallidus. During stimulation of the substantia nigra Pukinje cells activated by climbing fibers responded. Evoked complex discharges appeared after a stable latent period of 8.5±0.3 msec. Arguments are put forward regarding the role of the substantia nigra, the globus pallidus, nuclei of the inferior olive, and also the thalamic nuclei in the mechanism of caudato-cerebellar oligosynaptic and polysynaptic connections.N. I. Pirogov Medical Institute, Vinnitsa. Translated from Neirofiziologiya, Vol. 10, No. 4, pp. 375–384, July–August, 1978.     

Unit responses of the sensomotor cortex to paired electrical stimuli

Unit responses of the sensomotor cortex to paired electrical stimulation and visual cortex, applied either simultaneously or after various delays (from 0 to 200 msec) depend on the order of application of the stimuli and on the interval between them. If stimulation of the sensomotor cortex was used in a conditioning role the response continued unchanged when the intervals between stimuli were increased to 200 msec. If, however, stimulation of the sensomotor cortex had a testing role interaction was observed between the stimuli so that responses to both first and second stimuli were blocked; this was exhibited most clearly for intervals of 40–80 msec between stimuli. The blocking effect persisted on some neurons with delays of up to 200 msec between stimuli, while the response of others to both the first and the second stimulus was restored.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 5, No. 6, pp. 628–635, November–December, 1973.     

Electrophysiological study of connections between the entorhinal cortex and the neocortex

In acute experiments in rabbits immobilized by d-tubocurarine, stimulation of the entorhinal area with rectangular electric impulses led to the appearance of evoked potentials (EP) with a latent period of 6–12 msec in the occipital, temporal, parietal, and cingular areas of the neocortex. The amplitude of the positive response component was 500 µV, and its duration 25–50 msec. The negative component was not always discernible. When rhythmic stimulation was used, these EPs followed stimulation frequencies not exceeding 20 per sec. Stimulation of the medial parts of the entorhinal area with a frequency of one to three per sec was accompanied by recruitment of the EP in the occipital and temporal neocortex areas. Nembutal depressed the amplitude of the neocortex EP appearing in response to stimulation of the entorhinal cortex. With the aid of double stimulation it could be established that, after conditioning stimulation of the entorhinal area, the positive component of the primary response (PR) evoked by stimulation of the contralateral sciatic nerve in the projection zone of the somatosensory cortex is strengthened during the first 50 msec, and subsequently after 80–120 msec. In these cases, the negative component was depressed. These findings are discussed with a view to the influence of limbic structures on the neocortex.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 2, No. 1, pp. 73–78, January–February, 1970.     

Spontaneous and evoked unit activity of the septum and hippocampus transplated into the rat neocortex

Embryonic septal and hippocampal tissue was transplanted into a cavity formed by removal of part of the parietal cortex of adult rats by suction. By extracellular recording 4–6 months after the operation cells with spontaneous activity with a frequency of 3.6±0.4 Hz, characterized by an irregular, stochastic spike distribution, were detected in the graft. About 90% of cells responded to electrical stimulation of neighboring cortical areas after a latent period of 5–43 msec. The most stable responses appeared to stimulation with frequencies of 5–10 Hz; in most cases the evoked discharge was followed by a period of inhibition of spontaneous activity (100–700 msec). The same number of cells responded to tactile stimulation of the body surface and vibrissae of the recipient animal. Specific responses of different types with latent periods of between 50 and 600 msec were observed. Normalization of unit activity of intracerebral grafts compared with activity of cells in tissue developing in the anterior chamber of the eye, and their functional integration with the recipient's brain are discussed.Institute of Biological Physics, Academy of Sciences of the USSR, Pushchino-on-Oka. Translated from Neirofiziologiya, Vol. 17, No. 2, pp. 160–168, March–April, 1985.     

Postsynaptic neuronal response of a cat sensorimotor cortex during evoked and self-sustained rhythmic "spike and wave" activity

Intracellular correlates of complex sets of rhythmic cortical "spike and wave" potentials evoked in sensorimotor cortex and of self-sustained rhythmic "spike and wave" activity were examined during acute experiments on cats immobilized by myorelaxants. Rhythmic spike-wave activity was produced by stimulating the thalamic relay (ventroposterolateral) nucleus (VPLN) at the rate of 3 Hz; self-sustained afterdischarges were recorded following 8–14 Hz stimulation of the same nucleus. Components of the spike and wave afterdischarge mainly correspond to the paroxysmal depolarizing shifts of the membrane potential of cortical neurons in length. After cessation of self-sustained spike and wave activity, prolonged hyperpolarization accompanied by inhibition of spike discharges and subsequent reinstatement of background activity was observed in cortical neurons. It is postulated that the negative slow wave of induced spike and wave activity as well as slow negative potentials of direct cortical and primary response reflect IPSP in more deep-lying areas of the cell bodies, while the wave of self-sustained rhythmic activity is due to paroxysmal depolarizing shifts in the membrane potential of cortical neurons.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 18, No. 3, pp. 298–306, May–June, 1986.     

Role of the caudate nucleus in the development of evoked synchronized activity

Synchronized activity (spindles, augmentation response) evoked by stimulation of thalamic nonspecific, association, and specific nuclei was investigated in chronic experiments on 11 cats before and after successive destruction of the caudate nuclei. After destruction of the caudate nuclei the duration of spindle activity in the frontal cortex and subcortical formations (thalamic nuclei, globus pallidus, putamen) was reduced to only three or four oscillations. In the subcortical nuclei its amplitude fell significantly (by 50±10%); in the cortex the decrease in amplitude was smaller and in some cases was not significant. Different changes were observed in the amplitude of the augmentation response, depending on where it was recorded. In the subcortical formations it was considerably and persistently reduced (by 50±10%); in the cortex these changes were unstable in character. Unilateral destruction of the caudate nucleus inhibited synchronized activity evoked by stimulation of the thalamic nuclei on the side of the operation only. Destruction of the basal ganglia (caudate nucleus, globus pallidus, entopeduncular nucleus, and putamen) did not prevent the appearance of synchronized activity; just as after isolated destruction of the caudate nucleus, after this operation synchronized activity was simply reduced in duration and amplitude. It is suggested that the caudate nucleus exerts an ipsilateral facilitatory influence on the nonspecific system of the thalamus during the development of evoked synchronized activity.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 9, No. 3, pp. 239–248, May–June, 1977.     

Unit responses of the cat caudate nucleus to cortical stimulation before and after destruction of nonspecific thalamic nuclei

Responses of caudate neurons to stimulation of the anterior sigmoid and various parts of the suprasylvian gyrus were studied in acute experiments on cats. The experiments consisted of two series: on animals with an intact thalamus and on animals after preliminary destruction of the nonspecific thalamic nuclei. Stimulation of all cortical areas tested in intact animals evoked complex multicomponent responses in caudate neurons with (or without) initial excitation, followed by a phase of inhibition and late activation. The latent periods of the initial responses to stimulation of all parts of the cortex were long and averaged 14.5–25.5 msec. Quantitative and qualitative differences were established in responses of the caudate neurons to stimulation of different parts of the cortex. Considerable convergence of cortical influences on neurons of the caudate nucleus was found. After destruction of the nonspecific thalamic nuclei all components of the complex response of the caudate neurons to cortical stimulation were preserved, and only the time course of late activation was modified.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 12, No. 5, pp. 464–471, September–October, 1980.     

Effect of destruction of basolateral nuclei of the amygdala on the character of electrical activity of the dorsomedial thalamic nucleus in rats

Characteristics of slow global and of unit activity in the dorsomedial thalamic nucleus were studied at various times after destruction of nuclei of the basolateral amygdala in semichronic experiments on anesthetized rats. Destruction of this kind was found to cause periodic transformation of the neuronal discharge into rhythmic bursts of spikes, and into the development of bursts of paroxysmal activity in the form of groups of four to six pointed waves with a mean duration of 60.5±20.6 msec, appearing with a frequency of 1.5±0.3 Hz. A change in the coefficient of correlation was found between the duration of bursts and their frequency during the 20–22-sec period of their generation. Interference was demonstrated between bursts and orthodromic focal potentials, evoked by stimulation of the anterior periamygdalar cortex and anterior amygdalar region. Neurons were described with long (up to 1 sec) responses to stimulation of the periamygdalar cortex and amygdalar region, in the form of regular bursts of spikes or tonic activation, correlating with the appearance of a rhythmic after-discharge. Bursts of this kind, which were most marked during the first 3 or 4 days after destruction of the basolateral amygdala, were observed to begin to disappear toward the end of the first postoperative week. It is suggested that one mechanism of the change in the adaptive behavior of animals with destruction of the amygdala is a disturbance, linked with the bursts, of the relay and integrative functions of the dorsomedial thalamic nucleus.     

Dynamic characteristics of motor responses evoked by stimulation of the motor cortex in unanesthetized cats

Temporal characteristics of motor responses evoked in unanesthetized cats by stimulation of the motor cortex through bipolar needle electrodes were investigated in chronic experiments. Isometric and isotonic contractions of the flexor muscles of the hip and knee joints of the limb contralateral to the point of stimulation were recorded. The latent period of response varied from 100 msec or more in the case of low-frequency (100–150 Hz) and low-threshold (1.1–1.2 thresholds) stimulation of the motor cortex to 30–35 msec in the case of "optimal" parameters of stimulation (300–400 Hz, 1.5–1.6 thresholds). If the intensity of stimulation was high enough the rising time constant of evoked contraction was 50–80 msec; values of the falling time constant of muscular contraction after cessation of stimulation were much greater, namely 150–300 msec. The rising time constant of contraction decreased with an increase in both the frequency and strength of motor cortical stimulation. The results are examined and discussed from the standpoint of methods of automatic control theory.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 12, No. 5, pp. 451–458, September–October, 1980.     

The rhombencephalic "locomotor region" in turtles

Electrical stimulation (10–20 µA, 20–30 Hz) of the rhombencephalon in decerebrate turtles can induce cyclic coordinated limb movemnts. The "locomotor region" is a strip, oriented in the rostro-caudal direction, which coincides in its location with the lateral reticular formation. Both in the medial and in the lateral reticular formation extracellular ipsilateral and contralateral synaptic responses of single neurons evoked by stimulation of the "locomotor region," (10–30 µA, 2 Hz), were recorded. Usually these responses had latent periods of between 3 and 12 msec (mode 5–6 msec). Excitation of the "locomotor region" thus leads to extensive spread of activity in the rhombencephalon. The possible mechanisms of this spread are discussed.Institute of Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 12, No. 4, pp. 382–390, July–August, 1980.     

Unit responses in area 5b of the suprasylvian gyrus to stimulation of the posterior lateral thalmamic nucleus

In response to stimulation of the posterior lateral nucleus in unanesthetized cats immobilized with D-tubocurarine an evoked potential consisting of three components with a latent period of 3–5 msec appeared in area 5b of the suprasylvian gyrus. All three components were reversed at about the same depth in the cortex (1500–1600 µ). Reversal of the potential shows that it is generated in that area by neurons evidently located in deeper layers of the cortex and is not conducted to it physically from other regions. Responses of 53 spontaneously active neurons in the same area of the cortex to stimulation of the posterior lateral nucleus were investigated. A characteristic feature of these reponses was that inhibition occurred nearly all of them. In 22 neurons the responses began with inhibition, which lasted from 30 to 400 msec. In 30 neurons inhibition appeared immediately after excitation while one neuron responded by excitation alone. The latent periods of the excitatory responses varied from 3 to 28 msec. The short latent period of the evoked potentials and of some single units responses (3–6 msec) confirms morphological evidence of direct connections between the posterior lateral nucleus and area 5b of the suprasylvian gyrus. Repetitive stimulation of that nucleus led to strengthening of both excitation and inhibition. Influences of the posterior lateral nucleus were opposite to those of the specific nuclei: the posterior ventrolateral nucleus and the lateral and medial geniculate bodies. Stimulation of the nonspecific reticular nucleus, however, evoked discharges from neurons like those produced by stimulation of the posterior lateral nucleus.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 5, No. 5, pp. 502–509, September–October, 1973.     

Pattern and correlation of fast and slow spontaneous unit activity in the visual cortex

Spontaneous unit activity in the visual cortex and its changes during stimulation by continuous light or flashes were investigated in waking rabbits. The study of distributions of adjacent intervals showed that the neurons differ in the ratio of burst (fast, with intervals of up to 15–40 msec) and nonburst (slow) activity and in the character of changes from one type of activity to the other. Of the total number of spikes 63% were outside bursts; the ratio of their number to the number of spikes within bursts consisting of two or of three or more spikes was 27:3:1. The relative stability of the burst structure of spontaneous activity and the limited number of spikes in them (on average 2.4) were demonstrated. Bursts of three or more spikes (mean 3.6) were irregular, and in 79% of them a longer interval (18.6±2.4 msec) was observed before the shortest interval (7.9±0.9 msec). Bursts of spikes of most neurons during photic stimulation contain more spikes with shorter intervals; they also began more frequently with the shortest interval, possibly signifying an increase in the steepness and amplitude of the EPSPs lying at their basis. However, in 20% of neurons spontaneous bursts included more spikes and with shorter intervals than bursts evoked by flash stimulation.Research Institute of Psychiatry, Ministry of Health of the RSFSR, Moscow. Translated from Neirofiziologiya, Vol. 11, No. 4, pp. 311–320, July–August, 1979.     

Comparative characteristics of septal "burst" neurons after elimination of afferent effects of the reticular formation in the rabbit

Comparative analysis of characteristics of rhythmic theta-activity in the neurones of the medial septal nucleus and nucleus of diagonal band was performed in intact rabbits after. i. v. injection of pentobarbital, and in rabbits with chronic lesion of the ascending brain-stem afferent fibers. In both conditions theta-bursts disappeared in some cells with unstable periodic rhythmic modulation; substantial population of the septal units preserved regular burst activity. Main characteristics of theta-bursts were almost identical in both states, their mean frequency decreased to 3.5 Hz. The theta-rhythm in hippocampal EEG was usually absent; but low-frequency rhythmic activity could be evoked by electrical or sensory stimulation as well as by injection of bemegrid or physostigmine. The data show that the ascending brain-stem afferents control: the frequency of the bursts in a population of septal units regarded as bursting pace-maker cells; the total number of the septal cells secondarily (synaptically) involved into rhythmic activity. The effect of pentobarbital upon theta-rhythm results from elimination of these influences upon the septal cells.     

Features of evoked potentials in the cerebellar cortex of rabbits

We investigated evoked responses of the cerebellar cortex of rabbits under Nembutal or chloralose anesthesia to stimulation of the sciatic, brachial, and vagus nerves. The parameters of evoked potentials (E Ps), together with features of their distribution throughout the cerebellar cortex, enabled us to divide them provisionally into three types. Evoked potentials of the first type have a latent period of 5–10 msec and a two-phase or more complex shape. Evoked potentials of the second type have a latent period of 10–23 msec and include from one to four components. Evoked potentials of the third type are discharges with long latent periods (20–50 msec) and consist of a series of slow sinusoidal oscillations. Appearance of an initial electronegative component is characteristic of EPs of the cerebellar cortex of rabbits, especially those of the second and third types. Evoked potentials of the first type are local.N. I. Pirogov Vinnitsa Medical Institute. Translated from Neirofiziologiya, Vol. 1, No. 1, pp. 73–80, July–August, 1969.     

Self-sustained rhythmic spike and wave activity and response of glial and nerve cells in the cat sensorimotor cortex

During acute experiments on unanesthetized cats, immobilized with myorelaxants, it was found that during rhythmic stimulation (8–14 Hz, duration: 10 sec) of the ventroposterolateral thalamic nucleus brief hyperpolarization is succeeded by depolarization in the pyramidal neurons of the sensorimotor cortex. Following this depolarization, rhythmic (approximately 3 Hz) paroxysmal depolarizing shifts in membrane potential are produced by ending stimulation, succeeded by protracted hyperpolarization and termination of rhythmic wave activity. Depolarization only is observed in glial cells, however, while hyperpolarization sets in after hyperpolarization is completed in the neurons. It is suggested that long-term changes in the membrane potential of cortical cells could make some contribution to the setting up and termination of rhythmic spike and wave activity.I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 18, No. 3, pp. 319–325, May–June, 1986.