[Changes in the neuronal activity of the ventrolateral thalamic nucleus and in the motor components of an instrumental reaction in cats following the systemic administration of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)]. / Izmeneniia aktivnosti neironov ventrolateral'nogo iadra talamusa i dvigatel'nykh komponentov instrumental'noi reaktsii u koshek posle sistemnogo vvedeniia N-metil-4-fenil-1,2,3,6-tetragidropiridina (MFTP).

Activity of ventrolateral thalamic neurons during performance of instrumental reaction was studied in four cats before (81 neurons) and after (70 neurons) five injections of MPTP (5 mg/kg every day). It was found that MPTP administration was followed by a clear increase of the discharge frequency of the studied neurons correlated with forelimb movements. The duration of their excitation connected with movement initiation, flexion or extension of limb increased as well. Movement disorders that evidenced for the development of bradykinesia were observed simultaneously with an increase of the neuronal activity. Dophamine microinjection into the caudate nucleus led to recovery of movements and neuronal discharge frequency. A conclusion was made that in intact cats activity of ventrolateral thalamic neurons related to forelimb movements was under inhibitory influences coming from the nigrostriatal system.

[Various responses of neurons of the caudate nucleus in alert cats to visual stimulation]. / Raznoobrazie reaktsii neironov khvostatogo iadra bodrstvuiushchei koshki na zritel'noe razdrazhenie.

Activity of sixty two neurons of the caudate nucleus to the visual stimuli were recorded in awake cats. It was found that most (52%) of tested neurons gave visual responses of sensory type evoked by the appearance of light stimulus in the visual field and only 11% of them were of the motor type related to the guided eye movement to the target. About a quarter of neurons responded to biologically significant objects revealing nonspecific responses. Several types of visual responses could be recorded from the same neuron. The data obtained permit supposing the presence of several parallel pathways for afferent visual influences on the caudate nucleus.

[Pathways of visual and auditory information transmission in the caudate nucleus of the cat]. / Puti peredachi zritel'noi i slukhovoi informatsii v khvostatoe iadro koshki.

Visual and auditory projections to the caudate nucleus were studied in cat by combination of the HPR method and experimental degeneration of retinal axons. It was shown that visual information comes to the caudate nucleus not only through the well-known polysynaptic pathways from the cerebral cortex, but also through both oligosynaptic (via pulvinar, lateroposterior nucleus, suprageniculate nucleus and nucleus limitans of the thalamus) and disynaptic pathways (via medial and lateral terminal nuclei of the accessory optic tract, pulvinar, pretectum, intermediate superior colliculus layer, supraoptic nucleus) some of which were found for the first time. Direct retinal inputs to the suprageniculate nucleus were found. Additional sources of auditory information to the caudate nucleus were revealed being as follows: the dorsal nucleus of parvocellular division of the medial geniculate nucleus, deep superior colliculus layer, dorsal and ventral nuclei of the lateral lemniscus. Physiological significance of the revealed pathways for the possible transmission of visual and auditory impulses and a new principle of organization of sensory inputs to the caudate nucleus are discussed.

[Responses of neurons of the caudate nucleus of the cat during activation of attention by visual objects]. / Reaktsii neironov khvostatogo iadra koshki pri aktivatsii vnimaniia zritel'nymi ob"ektami.

Responses of caudate neurons to visual objects attracting attention to a target were studied in cats. The obtained responses were compared with those to local light stimuli exposed in the visual field during fixation of the gaze. Responses to single and repeated applications of the stimuli caused by both kinds of visual stimulation differed in their latencies and patterns. This permits supposing two different manners of visual activation of caudate neurons.

[Projections of the neurons of the medial terminal nucleus of the accessory optic tract to the caudate nucleus of the cat detected by the combined methods of retrograde axonal transport and experimental degeneration]. / Proektsii neironov medial'nogo terminal'nogo iadra dobavochnogo opticheskogo trakta k khvostatomu iadru u koshki, vyiavliaemye pri sochetanii metodov retrogradnogo aksonnogo transporta i éksperimental'noi degeneratsii.

Projections of neurons of the medial terminal nucleus of the accessory optic tract receiving direct retinal inputs to the head and body of caudate nucleus are shown in cat by the retrograde axonal transport of horseradish peroxidase and experimental degeneration. These projections are mainly ipsilateral and uniformly distributed in the above mentioned parts of the nucleus. The neurons of the medial terminal nucleus establishing synaptic connections with caudate neurons have different shapes and sizes (from 20 X 10 microns to 37.5 X 18 microns) and are located both in the ventral and dorsal parts of the nucleus. Conclusions are made about functional significance of these projections in the regulation of the muscular tension.

[Features of responses of the neurons of the caudate nucleus to various localizations of a photic stimulus in the visual field of the alert cat]. / Osobennosti reaktsii neironov khvostatogo iadra pri razlichnoi lokalizatsii svetovogo stimula v pole zreniia bodrstvuiushchei koshki.

The responses of caudate neurons to restricted light stimuli differently located in the visual field were studied during natural fixation of the gaze on the visual target in awake cats. 71% of visually responsive neurons were sensitive to changing of stimulus location. It indicates that some neurons (17%) had restricted receptive fields in the centre of the gaze, other neurons (17%) had decreasing sensitivity to stimuli removed from the centre of the field and 37% of responsive neurons received information of different quality from different parts of the visual field. It is suggested that caudate nucleus neurons participate in the analysis of visual sensory information.

[Sensory properties of neurons of a nonspecific brain structure--the caudate nucleus]. / Sensornye svoistva neironov nespetsificheskoi struktury mozga--khvostatogo iadra.

The paper deals with sensory function of single neurons in nonspecific high-level brain structures. Certain aspects of the problem are shown to be complex and disputable. The choice of the research object, nucleus caudatus, is substantiated. Results of experiments with alert cats are presented. Extracellularly recorded neuronal responses to various light stimuli are compared. Local light stimuli, especially under a definite spatial distribution of illuminated sites in the visual field, are found to be more advantageous in neuron activation than diffuse light. Difficulties in interpretation of the data obtained are discussed in connection with fluctuation of background activity and recorded responses under multiple application of the stimuli. An attempt is made to relate sensory properties of the neostriatum to the regulatory efferent function of this structure.

[Responses of caudate nucleus neurons to different visual stimuli in the actively awake cat]. / Reaktsii neironov khvostatogo iadra na razlichnuiu zritel'nuiu stimuliatsiiu u aktivno bodrstvuiushchikh koshek.

The responses of caudate neurons to diffuse or local (a slit) light stimuli were studied extracellularly in alert cats during natural fixation of the gaze. The number of neurons responding to local light stimulation was much higher than that responding to diffuse light. Local light stimulation produced more extensive inhibition of neuronal activity as well as "off" responses. Some neurons responded selectively to the orientation of slits. All neuronal responses were recorded with latencies of 40-90 ms. The participation of the caudate nucleus in the analysis of visual sensory information is discussed.

[Interaction of effects of functionally different zones of the cerebral cortex on the caudate nucleus neurons in the cat]. / Vzaimodeistvie vliianii funktsional'no razlichnykh zon kory golovnogo mozga na neironakh khvostatogo i adra koshki.

Extracellular recording from the caudate nucleus neurons was performed in experiments on immobilized cats during paired stimulation of anterior sigmoideus and middle suprasylvius gyri. The findings indicate that the two cortical areas influence these neurons, the motor cortex having a greater influence on caudate neurons than the association cortex. The same interaction was recorded after a deep transcortical dissection between the stimulated areas.

[Analysis of the spike activity of pairs of caudate nucleus neurons in cats]. / Analiz impul'snoi aktivnosti par neironov khvostatogo iadra koshki.

Spike activity of pairs of neurons was recorded simultaneously with a single microelectrode in the caudate nucleus of lightly anaesthetized immobilized cats. A high time correlation was observed in discharges of two neurons when their background activity showed group discharges. In case of unitary background activity, correlation between spike trains was observed only in 50% of the cells; it could be both of excitatory and inhibitory type. Many neuronal pairs exhibited negative short latency correlation in the 0--4 ms range. Electrical stimulation of different afferent inputs of the caudate nucleus caused minimal correlation between neuronal discharges and, on the contrary, abolished correlation between spontaneous discharges of the same pair of neurons. The presented results are discussed from the point of view of the caudate nucleus as an associative cerebral nucleus.

[Analysis of the background activity of cat caudate nucleus neurons]. / Analiz fonovoi aktivnosti neironov khvostatogo iadra koshki.

Background activity recorded extracellularly from the caudate nucleus neurons was analyzed in immobilized cats. Experimental data processing included the plotting of average frequency curves, interspike interval histograms, intensity functions, correlograms and association histograms. The frequency of the background activity in different caudate neurons varied from 0.5 to 20 imp/s and could change in the same neuron in different time intervals. According to the time structure and statistical parameters the background activity of the caudate neurons was classified in two types: unitary and group. Transformation from one type to the other could be observed in the same neuron. The obtained data do not allow considering the background activity of the caudate neurons as simple random pulse trains.

[Different forms of potentials discharged by caudate nucleus neurons]. / Razlichnye formy potentsialov, otvodimykh ot neironov khvostatogo iadra

Background and evoked activities of the caudate neurons were recorded extracellularly in acute experiments on cats. Different forms of potentials were observed in background and evoked activity. They could be divided into three types: (a) simple full size action potentials; (b) prepotentials characterized by smaller amplitudes and slower decrement; (c) complex discharges consisting of simple potentials of smaller amplitude accompanied by slow positive-negative waves. Prepotentials were observed in background activity separately or as components of full size spikes. Frequency range of complex discharges was 0.5-1 per s. Prepotentials and full size potentials were arrested by slow waves of the complex discharges. The observations are discussed with regard to the origin of diverse forms of the potentials in the caudate nucleus neurons and compared to those made on the cerebellar Purkinje cells.

[Reaction of caudate nucleus neurons to direct stimulation]. / Reaktsii neironov khvostatogo iadra na ego priamuiu stimuliatsiiu

Extracellular recording from the caudate nucleus neurons were performed in experiments on immobilized cats during electrical stimulation of different parts of the same nucleus. Latencies varied from 3.5 to 40 msec. Most neurons could be excited by stimulation of the most rostral part of the caudate nucleus head. In most cases responses were independent of the stimulation place. The responses consisted of one or rarely two spike followed by inhibition of background activity. Then activity gradually restored without rebound. Afterdischarges were not observed. The caudate neurons hardly reproduced stimulating frequencies more than 30 per second and retained in most cases their own frequency level (on the average 5-15 spikes/sec.). The results are discussed in connection with participation of the caudate nucleus in the origin of spindle activity.