[Nerve tissue transplantation as a method for the nonspecific modulation of higher nervous activity in animals].
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Animals↗
Biomedical subjects
V L Silakov
Publications and source records attributed to V L Silakov.
[A quantitative analysis of primate motor activity in a situation of delayed spatial choice. The individual behavioral reactions].
Speed of movements in food getting responses of baboons, total time of the response, trajectories of the movements and other parameters revealed obvious changes during formation of conditioned activity. The data obtained suggest that many quantitative characteristics of the primate motor activity are specifically related to various aspects of complex behavioral responses.
Animals↗
[An analysis of the joint activities of primates in a situation of delayed spatial choice].
A leader-dominant baboon of a couple took practically all the food in the situation of spatial delayed choice. The subdominant baboon managed to get some food, too, using fast changes of behavioral tactics during the experimental session. The obvious negative state of the subdominant baboon resulted in a severe neurotic breakdown. Long delays in the experimental scheme enabled the subdominant to get up to 50% of the food reinforcement due to the dominant baboons mistakes. The role of changes in the tactics of the monkeys is discussed.
Animals↗
[The plasticity of the hierarchical relationships in a pair of rhesus monkeys in competitive and noncompetitive food procurement].
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Animals↗
[Functional reorganization in the system of corticotectal connections after unilateral deafferentation of the cortex].
The responses of the cat's collicular neurons to direct stimulation (DCR) of contralateral neocortex were studied in various periods after unilateral dissection of cortico-subcortical connections. The data obtained suggest that, in intact cat's brain, during early hours of postoperative period, and within 1-2 years after the operation, functional specifics of contralateral motor and sensory projections to superior colliculus played a major part in determining basic features of compensatory shifts of the impulse activity of collicular neurons.
Adaptation, Physiological↗
[Demonstration of postural asymmetry factors in a hypophyseal tissue culture as affected by the cerebrospinal fluid of cats with unilateral damage to the hemispheric cortex].
It has been experimentally established that special hypophysiotropic factors--precursors of pose asymmetry factors (PAF) are found in the cerebrospinal fluid of donor animals with cortical lesions during the first postoperative hours. These factors, being specific for the location of the cortical lesion in donor animals, appear to be hypophysiotropic peptide substances inducing the production of corresponding PAF by hypophysial cells. The production of certain PAF by the rat hypophysial tissue cultures under the influence of cerebrospinal fluid from cats gives evidence in favour of species nonspecificity of PAF inductors.
Animals↗
[Effect of the cerebrospinal fluid from animals with motor cortex damage on the compensation of movement disorders].
Recipient rats with unilateral ablation of the motor cortex underwent suboccipital injection of the CSF obtained from donor rats with analogous damages of their motor cortex. The dose 150 microliter of the donor CSF was most effective rendering a considerable improvement of motor functions in the recipient rats. The data obtained suggest an essentially new technique of human brain trauma therapy using injections of donor CSF.
Adaptation, Physiological↗
[Changes in the functional characteristics of cells of the Clare-Bishop zone after unilateral partial isolation of the cat neocortex].
Evoked single cell activity in the Clare-Bishop area of the cat neocortex was recorded after partial transection of subcortico-cortical connections. Both functional properties of visual, auditory and somatosensory responsive cells and their responses to electrical stimulation of the primary projection area were studied. A week after transection some neurons in the Clare-Bishop area on the operated site recovered their reactions to applied stimuli. Within the first week the sensitivity of the neurons in the intact hemisphere changed; all the recorded cells reacted to light; 80% of the cells had receptive fields that were situated in the contralateral part of the visual area; 62% of the cells reacted to somatosensory stimuli. A week after the operation the number of responsive cells decreased. The peculiar features of the neuronal compensatory reorganization in the Clare-Bishop area and its role in the recovery of visual function is discussed.
Animals↗
[Long-term reorganization of the neuronal activity in field 7 of the neocortex in the cat after unilateral section of the visual radiation].
Changes in functional characteristics of area 7 cells were studied in cats under semichronic experimental conditions. The experiments were done in various periods of time after unilateral dissection of visual subcortic-cortical fibres. Neuronal responses to visual, auditory, somatic stimuli and electrical stimulation of primary cortical areas were studied in intact and impaired hemispheres. Reappearing of neuronal sensitivity to stimuli of various sensory modalities was found in the partially isolated neocortex. Both the number of cells with local visual receptive fields and averaged receptive field size of the cells increased slowly after the operation. Some suggestions about the nature of plastic changes developing in neuronal nets of the parietal cortex after impairment of subcortico-cortical connections are made.
Animals↗
[Compensatory reorganization of the visceral analyzer at the level of the neocortex].
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Adaptation, Physiological↗
[Convergence of corticofugal impulse projections onto superior colliculus neurons].
In unanesthetized immobilized cats, 82.75% of tectal neurons responded to direct electrical stimulation of different cortical areas. Stimulation of the associative and visual cortex was the most effective. On simultaneous presentation of light and electrical stimuli, facilitation of responses of the collicular neurons was prevalent. The role of striatal and extrastriatal effects of neocortex as well as the regularities of integration of retinotectal and corticofugal afferents upon the neurons of anterior colliculus, are discussed.
Animals↗
[Spike activity of superior colliculus neurons following blockade of corticofugal regulation].
Changes in background and evoked activity of the superior cooliculus neurons were studied in cats before and after cessation of ipsilateral corticofugal connections. On the operated side of the brain the superior cooliculus neurons slackened their impulsation and most of them were unresponsible to light stimulation (only 7.1% neurons responded to light after operation). It is suggested that afferent inputs to superior colliculus neurons are modulated by corticofugal mechanisms.
Animals↗
The interactions of central neurons in conditioning and the influence of some limbic structures upon them.
The interactions between the neurons in the cortex and the subcortical visual structures were studied with multimicroelectrode technique. Neurons revealing conditioned reactions were found at various levels of the brain. It is assumed that they are involved, by the conditioning, in a special cellular network: the microsystem, which is considered to be the definite functional level of brain processing mechanisms. The influence of some limbic structures on the formation of the microsystems of conditioning neurons was found. It was concluded that the elaboration or extinction of the temporary connection is performed through formation or destruction of a microsystem which takes part in the conditioning.
Animals↗
[Characteristics of residual neurons during retrograde degeneration in the lateral geniculate bodies of cats].
The daynamics of functional-structural characteristics of residual neurons was studied in the degenerated lateral geniculate body (LGB) in various periods of time (4-12 months) after neuronal isolation of the neocortex under which all geniculo-cortical connections were cut. Background and evoked spike activity in the degenerated geniculate body were studied as well as the number of persisting cells and their diameters. Neuronal receptive fields were found to undergo destruction along with the prolongation of postoperative period. A gradual diminution in the quantity of light sensitive cells was revealed. Background spike activity was predominantly of a simple type. Progressing decrease in cell number and cell diameters was observed under the morphological examination. Special features inherent in geniculate interneuronal relations are discussed.
Animals↗
[Long term transformation of neuronal activity in the superior colliculus isolated from corticofugal influences].
Neuronal activity of the superior colliculus isolated from the corticofugal influences was studied in various periods of time (from 3 to 20 months) after unilateral dissection of cortico-subcortical projections. In 16 unanesthetized immobilized cats, after the surgery, spontaneous activity of collicular neurons became more regular and with less complex bursts during the postoperative period. Evoked activity was completely suppressed during early hours of the postoperative period. Only 31.5% of collicular cells were sensitive to light 3 months after the operation. Evoked responses to light of 90.4% cells reappeared in the isolated colliculus not earlier than 10-12 months after the isolation, while directional and movement sensitivity practically did not restore even within 20 months after the surgery. Corticocollicular influences are considered to be a necessary condition for effective visual information processing in the colliculi superiores.
Animals↗
[Transformation of neuronal activity in the cat lateral geniculate body].
The neuronal activity transformations were studied in the cat LGB under the action of nembutal, light stimulation, and micropolarization of geniculate cells. The transformation of single spike activity into bursts was found to reflect the inhibitory state of the neurons. Their excitation entailed a reverse transformation. Short feed-back connections functioning within the microsystems of LGB neurons are supposed to underlie the transformations.
Animals↗
[The role of polymodal synaptic influences in the formation of temporary connections in the microsystems of association cortex neurons].
Significance of various sensory convergence of the neuronal activity was investigated in unanaesthetized cats in the process of elaboration of time connections. The elaboration of time connection was realized after studying neuronal responses elicited by the direct electrical or sensory stimulation (light, sound, tactile and proprioceptive stimulation). 42 per cent of all neurons and about 90 per cent of learned cells were found to be polysensory in the investigated cortex. The data obtained are considered from the standpoint position of the hypothesis on the microsystem principle of organization underlying time connection and convergence.
Animals↗
[Changes in the receptive fields of cat lateral geniculate body neurons following removal of corticofugal influence].
The number of spikes in responses of the lateral geniculate neurons increased after section of ipsilateral corticogeniculate connections. The operation caused a distinct intensification of lateral inhibition effects in the operated side. Zones of complete spatial summation in the receptive fields of neurons in the operated side changed according to the contrast of the used light stimuli. It is suggested that corticogeniculate influences are of inhibitory nature and that receptive fields possessing a changing zone of spatial summation are realized by intrageniculate mechanisms.
Animals↗