Spike activity of the symmetrical points of the sensorimotor cortex was studied in the course of formation and extinction of a defensive conditioned reflex in cats. In the process of pairings the impulse responses in the hemisphere contralateral to the paw stimulated with electric current (reinforcement) increased, and were inhibited in the ipsilateral hemisphere. Extinction of the reflex or functional switching off of the contralateral hemisphere restored the conditioned reactions of the ipsilateral hemisphere neurones. An assumption has been made that conditioned connections appear in both hemispheres, but under ordinary conditions the reactions are ensured by the dominating (in learning) hemisphere. If it is switched off, a duplicate conditioned connection appears in the other hemisphere, as one of the mechanisms providing for the reliability of manifestation of the conditioned relfex.

Animals↗

PubMedDate not supplied

[Neuronal organization of a focus of unconditioned excitation in the cat sensomotor cortex].

The impulse activity of sensorimotor area neurones, situated near the point of its direct electrical stimulation used as a reinforcing stimulus, was studied in cats. The rearrangement of impulse activity during reflex elaboration consisted in the reduction of frequency of background activity, in changes in the character of neuronal reactivity and of the pattern of response to the signal and reinforcing stimuli. During the reflex elaboration the percentage of polymodal neurones increased. Tonic response to the conditioned sound stimulus changed into a phasic one. The inhibitory component of responses to direct electrical stimulation of the sensorimotor cortex became more protracted.

Animals↗

PubMedDate not supplied

[Role of functional asymmetry of the cerebral hemispheres in organization of an instrumental alimentary conditioned reflex in cats].

During instrumental alimentary conditioning in cats the speed of reflex stabilization depended on the correspondence between the dominant leg's lateralization and the side of the lever, which the animal had to press in response to the signal. When the lever was on the side of the dominant leg, the speed of the conditioning was greater than in the absence of such correspondence. Functional switching off (KCl) of the cortex of any hemisphere at the stage of reflex stabilization does not disturb the instrumental reaction. The switching off of the dominant hemisphere at the stage of stable reflex disturb the instrumental reaction, but has no effect on more simple forms of conditioned behaviour, e. g. run to the feeding through in response to the signal.

Animals↗

PubMedDate not supplied

[Elementary neuronal ensembles as the basis for the functional organization of the brain].

The structural basis of neuronal assemblies is made up of morphological associations of neurones determined by the properties of the central projection of afferent pathways. Underlying the functional organization of probabilistic neuronal assemblies is the formation of conjugated relations between neurones of the central zone of synergically activated units and the surrounding zone of inhibited neurones. The characteristics of informational activity and neuronal assemblies are related to the optimization of perception processes and reorganization of sensory information, and to the selection of useful information from the general sensory flow, especially in the course of formation of a habit. The observed characteristics of the work of probabilistic neuronal assemblies are considered as manifestations of formation of structural, functional and informational redundancy, the basic mechanism ensuring reliable functioning of the informational-controlling brain systems.

Adaptation, Physiological↗