Search PubMed⌕ Search

Biomedical subjects

N Iu Belenkov

Publications and source records attributed to N Iu Belenkov.

At least 19 recordsLinked to original sources
PubMed1987

[Role of endogenous neurohumoral factors in mechanisms of the pathogenesis and compensation of unilateral movement disorders after serial removal of the motor neocortex].

The role of neurohumoral factors in the mechanisms of restoring the lost motor functions after two successive unilateral removals of the neocortex motor region, was studied. The dynamics of the restoring correlated with the posture asymmetry factor (PAF) activity in the CSF. PAF activity was reduced during the restoring by an inactivation factor (FI). Periods of restoration after the 2nd extirpation and inactivation of PAF were shorter than after the 1st one. The existence of the FI before the 2nd extirpation may account for this phenomenon.

Adaptation, Physiological↗
PubMed1982

[Structural-functional reorganization of the brain after sequential removal of the regions of the motor cortex in cats and dogs].

It was shown in experiments on cats and dogs that the greater the mass of removed motor cortex on one side, the longer the time for restoring lost motor functions. Repeated ablations of the areas adjacent with the previously extirpated cortical zone after the restoration of motor functions, bring about the recurrence of the same disturbances. However the period of restoration after each repeated extirpation is perceptibly shorter. This means that repeated extirpations of cortical areas result in the activation of the mechanisms directed at the reorganization of the brain sensorimotor functions as a new integral system and providing for normalization of the motor functions.

Animals↗
PubMedDate not supplied

[The role of the temporal neocortex in the origin of convulsive activity].

Experiments on cats with cooling capsules implanted over different areas of the neocortex have shown that cooling of different intensity applied to the temporal neocortex may result in both stimulation and switching off effects. Cold stimulation (temperature dropping to 27-33 degrees C) manifested in generalized epileptiform brain electrical activity and paroxysmal states. The functional switching off the temporal area observed during its deeper cooling (20-21 degrees C) discontinues the paroxysmal state already developed and prevents the appearance of seizures, regrardless of the localization of the epileptogenic focus. The paroxysmal state weakens and ceases after repeated cooling of the temporal neocortex. The temporal neocortex, involved in the integrated activating brain system, plays a decisive role in the emergence of paroxysmal states.

Animals↗
PubMedDate not supplied

[Systems mechanisms of internal inhibition].

The state of internal inhibition is analysed which is considered as a multifactor systemically organized process. On model of combined presentation of positive and inhibitory stimuli in experiments on white rats and dogs, a dependence is established of the efficiency of reinforcement cancellation factor on motivation intensity. Condition of negative emotion--frustration, "difficult state"-is a necessary link in the process of internal inhibition formation, since it is responsible for selection of non-reinforcement for storage in the long-term memory. Conclusion is made that active inhibition of goal-directed behaviour is mediated by actualization of memory trace, "engram of non-reinforcement" by negative conditioned stimulus.

Animals↗
PubMedDate not supplied

[Importance of traces of a preceding unreinforced stimulus to the formation of inhibitory conditioned reflexes in the rat].

The results of experiments with the inhibitory signal presented to rats after the positive one, showed the significance of the negative signal memory trace which interrupted alimentary behaviour and considerably accelerated its full extinction in response to the previously positive signal. Its significance is shown in experiments with amnesia produced by electroshock. According to the suggested concept negative conditioned reflexes are a result of formation of a temporary connection between memory traces of the negative conditioned signal and the non-reinforcement of this signal.

Animals↗
PubMedDate not supplied

[Probability analysis of elements of rat behavior after sudden and signalled interruption of food reinforcement].

Probability analysis was carried out of the appearance of single elements of rats behaviour in the process of extinction of a conditioned alimentary motor reflex. The dynamics of effector behavioural components at a sudden cessation of reinforcement (usual schedule of extinction) was compared with cessation of reinforcement signalled by a previously differentiated signal and with reinforcement cessation preceded by a stimulus initially unknown to the animal. If the reinforcement cessation is signalled by a previously differentiated (negative) stimulus, in response to its action the animals "loose the aim", what is revealed in a rapid complete reduction of all elements of the goal-directed alimentary behaviour. Obviously differentiation signal actualises the memory trace of "nonreinforcement" which was formed in the previous negative experience of the animal; this is revealed in accelerated inhibition of the alimentary motor reflex under extinction.

Animals↗
PubMedDate not supplied

[Reactivity of neurons of the orbito-frontal cortex of the cat during exposure to the scent or sight of food].

Reactivity of neurones in orbitofrontal cortex of the cat to the action of light or sound was studied in consecutive stages of alimentary behaviour conditioned by the smell and then the sight of food. Changes were found of the character of neuronal reactions to the light and sound stimuli at the change of smell to the sight of food. A conclusion is drown, that polysensory properties of the neurones of the orbitofrontal cortex provide integral organization of brain sensory function at separate stages of alimentary behaviour.

Animals↗
PubMedDate not supplied

[Change in the functional significance of structures of the cat brain as a result of reorganization of its activity].

A study was carried out on 8 adult cats of functional role of the frontal, parietal and occipital parts of the neocortex, and also of the dorsal hippocampus, mediodorsal thalamic nucleus and caudate nucleus head, in realization of a delayed spatial choice (DSCh) before and after compensatory reorganizations of the brain activity caused by multiple electrical stimulation of the frontal part of the cerebral cortex. Compensatory reorganization led to a change of functional significance of these structures. While before this change the frontal cortex, hippocampus and mediodorsal thalamic nucleus were critically necessary brain areas for the realization of the DSCh, after it parietal and occipital cortical areas acquired such significance. The obtained data are discussed proceeding from the principle of the integrity in the brain activity.

Animals↗
PubMedDate not supplied

[Stimulus recognition as a factor in establishing the effective properties of the signal].

An attempt was made to estimate the importance of preliminary perceptual learning of the recognition of indifferent stimulus for the formation of effective properties of the trigger signal of conditioned reflex functional system. The dynamics of the elaboration of instrumental conditioned reflexes was compared: 1) when an unfamiliar signal was introduced into the experimental environment (control experiments). 2) in case of introduction of a perceptually familiar signal, 3) after "erasing" of acquired perceptual experience by electroshock. The experiments revealed that a preliminary perceptual learning contributes to the formation of the effective properties of the trigger signal.

Animals↗