[Dynamics of driven rhythm in neuron in sensorimotor cerebral cortices in rabbit on electrodermal paw stimulation].

The dominant centre is a zone of proof higher excitation of neurons in the cortex of the brain, resulting from long stimulation or effector (in our case of a forepaw of an animal) or direct cortical representations of this effector. Besides of higher excitation and the firmness of excitation neurones, the dominant centre has two more very important properties--ability to summation (addition) coming to a cortex and extending on cortical neural networks excitations and inertia. Last property is shown what even in some days after the termination of the stimulations which have formed a dominant, in reply to testing stimulus (earlier indifferent for an animal) the centre is activated and puts in action effector.

[Time and space distribution of coincident impulses in closed neural circuits in the sensorimotor cortex of the rabbit (the rhythmical defensive dominanta)].

In the course of analysis of the conjugate unit activity of simultaneously recorded neurons in the sensorimotor cortex of rabbits, 22 closed neural circuits consisting of 3 or 4 neurons were considered. In the model of the defensive dominanta, 1-3 weeks after imposing rhythmic (2 s) activity to a rabbit, the distribution of coincident impulses was analyzed in real time. It was found out that the events when the coincident impulses of neural pairs were generated with two-second intervals could be shifted in time and space over a closed circuit of neurons in one direction.

[Cortical network activity before behavioral reaction and before its omission in rabbits with defensive dominanta].

Defensive dominanta was formed in rabbit CNS. Activity of the cortical neuronal network was investigated in these rabbits in the state of quiet wakefulness and in the intervals between the presentations of testing stimulus (light flashes). Statistical analysis of spike trains revealed some distinctions in neuronal functional organizations in the excitation focus (sensorimotor cortex) and in the visual cortex in the states of quiet wakefulness, before the movement of the paw, and before the omission of the reaction.

[Dynamics of driven rhythm in neuronal assemblies in sensorimotor and visual cerebral cortices in rabbit].

Coincident activity of pairs of neurons in the sensorimotor and visual areas of the cerebral cortex was studied in naive, learning, and trained rabbits during the formation of a hidden excitation focus in their central nervous system (a defensive dominanta) of the rhythmic nature. In the trained rabbits (as compared to the naive animals), percent of neuronal pairs (both neighboring and distant) in whose coincident activity the rhythm of stimulation prevailed was higher. In the visual cortex, percent of such pairs was significantly higher only for the distant neurons.

[Neuronal correlates of changes in the time parameters of motor reactions in rabbits after tonic immobilization].

The latent excitation focus in the sensorimotor cortex of rabbits was formed by a series of pulses of the threshold current applied on a paw with 2-second intervals. After repeated applications of the routine immobilization procedure, besides the 2-second starts of the paw in response to testing stimulus, spontaneous starts appeared with the intervals close to 3 and 4 seconds. The analysis of the coincident (interconnected) activity of pairs of nearby neurons in the sensorimotor cortex of three rabbits repeatedly exposed to the immobilization procedure showed that (a) in situations when animals made movements with the intervals of 2 seconds, the 2-second rhythm prevailed in the coincident activity of neurons; (b) during movements made with the 3-second interval, a 3-second rhythm was more frequently revealed in the coincident activity of cells, (c) in the situations when the animals did not make movements, either 2-, or 3-second rhythms were equiprobably observed in the connected activity of nearby neurons.