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The changes in the functional characteristics of neurons of field 4 of the motor cortex (MC) of cats before and at various times (from a week up to five months) following an ipsilateral lesion of the ventrolateral nucleus of the thalamus were investigated in semichronic experiments. The reactions of the cells to tactile stimulation of the forelimb and its passive movement at the wrist at an average speed of 170 degrees/sec were studied. It was demonstrated that a correlation between the impulse activity at speed maxima and the acceleration of monoarticular movement is characteristic for a number of cells of the MC of the intact brain. Experimental confirmation was obtained of the hypothesis, formulated on the basis of the results of preceding investigations, regarding a disturbance of the mechanism of detection by MC neurons of the kinematic indicators of movement following damage to the thalamus. It was established that compensation of this disturbance is associated with the facilitation of conduction to MC neurons of somatosensory afferentation. It is concluded that a morphofunctional reorganization of particular intracortical components of sensorimotor coupling underlies the mechanisms of the compensatory plasticity of the MC.

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The kinematic parameters of the manipulatory motor reactions in the dynamics of the formation and consolidation of a precision skill consisting in the displacement and subsequent holding of a lever in a zone of "work" space signalized by a sound were studied in experiments on cats. It was established that the development of the skill passes through a stage of disinhibition of slow movements with a prolonged increase, prior to the appearance of the sound signal, in velocity. The skill which is consolidated in the course of subsequent training sessions is accomplished by uniform movements of the ballistic type, and is characterized by independance from the acoustic indication of the final position. At the same time, the relationship of the duration of the increase in acceleration to the beginning of the inhibition of the movement becomes an invariant parameter of the central program of the precision reactions.

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