[Effect of destruction of the ventrolateral nucleus of the thalamus on evoked potentials in the sensomotor region of the cortex in cats].
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Animals↗
Biomedical subjects
Iu A Iunatov
Publications and source records attributed to Iu A Iunatov.
[Cortical biopotentials following intracortical injections of kainic acid].
The morphological analysis after intracortical injection of kainic acid revealed lesions of cell bodies and dendrites and intact afferents in the same cortical region. After the injection, the primary positive phase of cortical surface EPs during stimulation of the ventrolateral nucleus or contralateral forepaw disappeared whereas the negative phase remained though with a lesser amplitude, shortened latency, and not inverted in the deep cortical layers. The dendrite potential on the cortical stimulation was completely depressed in the poisoned cortical region. The initial positive phase seems to reflect the postsynaptic hyperpolarization of apical dendrites whereas the initial negative phase seems to consist of both pre- and postsynaptic components across the whole cortical diameter.
Animals↗
[The characteristics of the neuronal reactions of the cat somatosensory cortex to a heteromodal complex conditioned signal].
On alert cats the change was studied of the activity of the neurones of the sensorimotor cortical area at instrumental reaction to a simultaneous heteromodal complex stimulus. It was shown that in the projection of distal limb areas a group could be singled out of neurones, which changed their activity in one direction depending on the character of presented signals. In these cells an increase of discharges frequency was observed in response to complex stimulus, consisting of light and sound signals. After the extinction of the motor reaction both to the complex stimulus and to its components neuronal reactions of lesser intensity was recorded, what determined the absence of the motor reaction. This group of neurones had receptive fields localized on distal limb areas, it was activated at fulfillment of the movement of catching the reinforcement and belonged to neurones of the pyramidal tract. The neurones with receptive fields on the whole limb surface or changing their activity at the animal pose change, had variable reactions to positive and differentiation stimuli.
Acoustic Stimulation↗
[The dependence of the neuronal reactions of the sensorimotor cortex to a simultaneous complex stimulus on the level of the differentiation of its components].
On alert animals the change was studied of the neuronal activity of the sensorimotor cortical area of cats brain in dependence on the level of differentiation of the components of simultaneous heteromodal complex stimulus. According to the character of this dependence and a number of other parameters two groups of neurones were singled out in the sensorimotor cortex. It was shown that parameters of reactions of all recorded neurones of the sensorimotor cortex to the positive conditioned signal were the first established after consolidation of the animal conditioned motor activity. In the course of elaboration following parameters changed: expressiveness, intensity, duration and value of latency. Reactions of neurones of both groups to the inhibitory stimuli were stabilized only after consolidation of the habit of differentiation. Responses of the first group neurones changed only by the pattern of discharge, while the responses of the second group neurones could change by expressiveness of response, its sign, duration and value of latency. Oscillations of the differentiation level after finishing of the elaboration of inhibitory conditioned reactions affected only the responses of the second group neurones to complex components.
Acoustic Stimulation↗
[Characteristics of the response of sensomotor cortex neurons of the cat during performance of rapid purposeful movements].
Neuronal activity of cat sensorimotor cortical area was studied during performance of movements of grasping a visual goal appearing for a short time. Characteristics and the pattern of neuronal discharge became stabilized in the process of animal training and did not depend on the time of goal presentation, absence or presence of the reinforcement under preservation of animal's motor reaction. Changes in responses were observed in situations of uncertainty: at 50% of reinforcement probability and (or) at successful performance of the motor reaction in half of cases.
Animals↗
[Participation of the ventrolateral thalamic nucleus in organizing visually controlled movements in the cat].
The role of the ventro-lateral thalamic nucleus (VLN) in organization of visual-motor coordination in cats is being considered. It is shown, that VLN destruction leads to inability to form new visual-motor coordination and only temporarily worsens previously elaborated coordination. Ventral and dorsal parts of VLN participate in organization of various types of movement: destruction of the ventral part tells upon rapid ballistic movements, whereas destruction of the dorsal part leads to disturbances of slow tracing movements of animal's limb.
Animals↗
[Modified method of training cats using visually controlled signalling].
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Animals↗
[Effect of damage to the associative zones of the neocortex on visuomotor coordination in cats].
The changes in characteristics of motor reactions, performed under constant visual control, were studied after lesion of separate associative zones in the cat neocortex. It was shown that the ability to perform a given task is impaired after local lesions of the sensorimotor cortex and extensive ablation of the parietal cortical areas. At the same time an increase of reaction temporal parameters is noted, which correlates with changes in the strategy of animal's search movements. Alone the ablation of the occipital areas does not impair the task performance. In case of local lesion of the parietal areas and the frontal pole of the cortex the preoperational level of task performance is preserved, but the time of search increases and the pattern of search movements is changed specifically for each cortical area.
Animals↗