[Convergence and interaction of reticulofugal and afferent impulses on caudate nucleus neurons in the cat]. / Konvergentsiia i vzaimodeistvie retikulofugal'noi i perifericheskoi afferentnoi impul'satsii na neironakh khvostatogo iadra koshki.

In chronic experiments on cats the activity of 269 striatal neurons was investigated extracellularly under direct electrical stimulation of the midbrain reticular formation and using different sensory stimuli: auditory, mechanical, visual. The same striatal neuron responded to reticular and peripheral stimulations. The responses to reticular stimulation recorded in 53% of striatal neurons were orthodromic with high probability of appearance. 23% of striatal neurons responded to reticular stimulation and to stimuli of a single modality. 14% of neurons exhibited polymodal responses. Under all kinds of stimulation excitatory reactions prevailed. Interaction between reticular and acoustic inputs was revealed with paired stimulation in 100 striatal neurons. The reticular formation stimulation caused both facilitatory (predominantly) and inhibitory influences on striatal neurons.

Spontaneous and evoked activity of neurons in deep structures of the brain during their anodal polarization.

The influence of anodal polarization on the spontaneous activity of neurons in the caudate nucleus, medial geniculate body, and the median center of the thalamus and on the evoked impulse activity of neurons in the medial geniculate body was investigated during auditory stimulation. The impulse activity was recorded extracellularly with glass and metallic microelectrodes. Nichrome polarizing electrodes of 0.2 mm diameter with an uninsulated tip of 0.3 mm were inserted into the foregoing structures in a packet. Current parameters evoking the reversible suppression of spontaneous and evoked neuronal activity were determined: 300-500 microA during exposure for 1-3 min at a distance of up to 3 mm from the polarizing electrode. After the cessation of polarization, a prolonged aftereffect was observed: The inhibition of evoked discharges lasted 4-10 min, and the evoked impulse responses disappeared for 5-20 min.

[Responses of caudate nucleus neurons to acoustic stimulation during functional blockade of the centrum medianum of the thalamus in the cat]. / Reaktsii neironov khvostatogo iadra na zvukovoe razdrazhenie pri funktsional'nom vykliuchenii sredinnogo tsentra talamusa u koshek.

Responses of caudate nucleus to sound clicks (0.5/s) were recorded extracellularly in chronic experiments on cats under conditions of functional blockade of centrum medianum. Analysis of average poststimulus histograms has shown that functional blockade of centrum medianum in 30% of the caudate nucleus neurons induced a decrease in phasic activating responses to sound signals and in 52% of neurons their disappearance. A decrease in the level of spontaneous caudate nucleus neurons activity was also found. Direct pathways from centrum medianum to caudate nucleus are discussed for their significance in transmission of sound signals to caudate nucleus neurons.

[Spontaneous and evoked activity of neurons of the deep structures of the brain in response to anodal polarization]. / Spontannaia i vyzvannaia aktivnost' neironov glubokikh struktur mozga pri ikh anodnoi poliarizatsii.

In cats, the effect of anodal polarization on the spontaneous unit activity of the caudate nucleus, MGB, center median and on the evoked unit activity of the MGB during sound stimulation, was studied. The polarization (300-500 microA for 1-3 min, at the distance up to 3 mm from the polarizing electrode) caused a reversible inhibition of the spontaneous and evoked unit activity followed by a prolonged aftereffect: inhibition of the spontaneous discharges for 4-10 min and disappearance of the evoked unit responses for 5-20 min.

[Reaction of caudate nucleus neurons to acoustic stimulation during functional exclusion of the medial geniculate body]. / Reaktsii neironov khvostatogo iadra na zvukovoi razdrazhitel' pri funktsional'nom vykliuchenii medial'nogo kolenchatogo tela.

In chronic experiments, responses of the cat caudate nucleus neurons to sound clicks (0.2/s) were recorded extracellularly under conditions of functional blockade of the medial geniculate body (MGB). Analysis of the average poststimulus histograms showed that, under anodic polarization of the parvo- and magnocellular parts of the MGB, 39% of the caudate nucleus neurons responded to sound signals by a decrease of phasic activation and 30% of neurons--by its disappearance, 9%--by lengthening of latency of the responses. In some units the anodic polarization of the MGB magnocellular part induced an increase in phasic activation. Stimulation of the MGB exerted a facilitating effect on the unit responses of the caudate nucleus to clicks.

[Short-latency responses of neurons of the striate system of the brain to sensory activation]. / Korotkolatentnye otvety neironov striatnoi sistemy mozga koshki na sensornuiu aktivatsiiu.

Experiments were carried out on awake cats to study responses of caudate neurons to different afferent stimuli (visual, auditory, somatic and direct electrical stimulation of medial geniculate body). Mean response latencies varied within 15-55 ms with the maximum value to 200 ms. At the same time 1-10% of cells responded with short latency to all applied stimuli. Significance of short-latency sensory responses in comprehension of principles of sensory processing in non-specific subcortical structures is discussed.

[Activity of caudate nucleus neurons during purposeful and forced limb movements in the alert cat]. / Aktivnost' neironov khvostatogo iadra pri tselenapravlennom i naviazannom dvizhenii konechnosti u bodrstvuiushchikh koshek.

Experiments were carried out on freely moving cats in a screened chamber. Activity of 121 neurones of the caudate nucleus head was examined during various sensory stimulations and during realization of components of a behavioural act (natural food-procuring reflex). No prevailing was found of neuronal reactions to impulses from passively contracting muscle groups of the body and the limbs over responses of the same neurones to sensory stimuli or limb movements during food-procuring reflex. A part of the caudate neurones manifested selective reactions. Three neurones reacted only to the opening of the door of the feeding trough, eight neurones changed their activity only during eating, and seventeen neurones reacted only to goal-directed limb movement. Participation of the neostriatum in sensorimotor integration is discussed.

[Study of the response of caudate nucleus neurons to direct electric stimulation of the medial geniculate body in the cat]. / Issledovanie reaktsii neironov khvostatogo iadra na priamoe élektricheskoe razdrazhenie medial'nogo kolenchatogo tela u koshki.

Extracellular activity of 124 caudate nucleus neurons during stimulation of parvo- and magnocellular parts of the medial geniculate body by rectangular electrical stimuli were investigated in chronic experiments on cats. Reactions were observed in 54 neurons (43%). Main types of responses were: phasic activation in the form of a single spike or spike discharge, initial activation followed by inhibition and pure inhibition. Excitatory responses prevailed (81% of the reacting neurons). The latent periods in different units fluctuated from 2.7 to 64 ms. In the same unit the latent periods were also very variable, which permits considering them as orthodromic. The mode of the histogram of the latent periods of the excitatory responses was in the range of 9-12 ms. The latent periods of the inhibitory responses varied from 12 to 130 ms and were in most neurons in a range of 40-60 ms. The increase in stimulus intensity led to an increase in response regularity, an increase in the number of spikes, reduced latent periods. In the same neuron the character and the structure of responses to stimulation of the relay nucleus and to sound clicks were usually identical. The latent period of responses to clicks was larger. Peculiarities of functional connection of the medial geniculate body with the caudate nucleus as a forebrain polymodal unspecific structure are discussed.

[Reactions of caudate nucleus neurons to presentation of acoustic clicks to cats in a chronic experiment]. / Reaktsii neironov khvostatogo iadra na pred''iavlenie zvukovykh shchelkov u koshek v khronicheskom éksperimente.

Background and evoked activities of the caudate nucleus neurons to repetitive auditory clicks were recorded extracellularly in chronic experiments with partial restrained cats. Four types of background neuronal activity were distinguished. 44% of recorded units altered their background activity during auditory click applications. Five types of neuronal responses were found: phasic activation, phasic inhibition, tonic activation, tonic inhibition, mixed tonic reactions. Tonic activation was predominant. The phasic responses persisted under prolonged presentation of clicks. Partial or total attenuation of tonic responses during frequent repetition of clicks occurred in 33% of responding units. The question is discussed on the convergence of specific and unspecific influences on the caudate nucleus neurons.

[Responses of cat caudate nucleus neurons to acoustic stimulation]. / Otvety neironov khvostatogo iadra koshki na zvukovye razdrazheniia.

Reactions of 141 cat caudate nucleus neurons to auditory signals--tone (500 and 2000 Hz) and clicks with different frequency (0.2 and 0.8/s) and intensity (75, 80, 95 dB) were recorded extracellularly. Neuronal reactions were highly variable as to the character of responses (phasis, tonic), their structure (one or two phases of activation), latent periods (from 7.5 to 300 ms), discharge frequency in burst responses (from 90 to 800 imp/s). Analysis of the averaged poststimulus histograms and plots of the dynamic reaction modifications showed that in most units (74%) the responses became considerably better expressed in case of a decreased stimulus frequency: the response regularity and the number of spikes in each response rose. The neuronal reactions also increased and acquired more distinct time structure with an increase in the stimulus intensity, 17% of recorded units showed qualitative differences in the character of neuronal reactions to clicks and tones: phasic activation arosed to clicks and tonic change of pulse activity occurred to tones. Peculiarities of the caudate nucleus neuronal reactions to auditory stimuli with different parameters are discussed.

[Effect of switching off the globus pallidus on alimentary and electrophysiologic responses induced by stimulation of the hypothalamus]. / Vliianie vykliucheniia blednogo shara na pishchevye i élektrofiziologicheskie reaktsii, vyzyvaemye stimuliatsiei gipotalamusa.

In chronic experiments on eight cats a direct electrical stimulation of the lateral hypothalamus evoked: 1) food eating in a state of satiation and 2) a reproduction of a conditioned food-procuring reflex, preliminarily elaborated to an acoustic signal. Bilateral electrolytic ablation of the globus pallidum abolished both reactions, but for different time periods. The first one was restored spontaneously on the 20th to the 46th day; the second disappeared for 2.5 to 8.5 months without spontaneous restoration. Stimulation of the lateral hypothalamus alimentary zones brought about a statistically significant rise of the thresholds of desynchronization reactions in the ipsi- and contralateral sensorimotor cortex. The activating role of the globus pallidum in the organization of a motivational alimentary excitation is discussed.

[The effect of ablation of the caudate nucleus on the alimentary zone of the lateral hypothalamus]. / Vliianie razrusheniia khvostatogo iadra na pishchevye zony lateral'nogo gipotalamusa

A conditioned food-procuring reaction previously elaborated to an acoustic stimulus was reproduced in chronic experiments on six cats by means of direct electrical stimulation of the posterior parts of the lateral hypothalamus. Folloiwng extensive bilateral electrolytic ablation of the caudate nucleus, conditioned food-procuring reaction to the stimulation of the hypothalamus could not be reproduced for 40 to 70 days. The conditioned foor-procuring reflex to the acoustic stimulus disappeared for 14 to 30 days to be subsequently spontaneously restored. After caudatotomy, a diminution of the average amplitude of background oscillations and of evoked potentials to acoustic stimuli was recorced in the examined zones of the lateral hypothalamus. The part played by the caudate nucleus in the processes of alimentary behaviour activation is discussed.