[Long-term rearrangements of the processing of kinesthetic afferentation at the neuronal level of the cat motor cortex after damage to the ventrolateral thalamic nucleus].

Single-unit recordings from motor cortex (area 4) were obtained in cats and under semichronic experimental conditions before and within various periods (from a week to five months) after the lesion in thalamic nucleus ventralis lateralis (n. VL). Neuronal responses to tactile stimulation of the contralateral forelimb and its passive movement in the wrist joint with the mean speed 170 degrees/s were studied. As it had been already reported by others, the magnitude and time course of averaged response histograms for some neurons, which were evoked by imposed displacements of the forelimb, were related to the velocity and/or acceleration components of the movements. Spontaneous firing and kinematic processing capabilities of motor cortical cells were affected by the lesion. The findings are in agreement with a hypothesis that n. VL is essential for encoding specific kinematic features of angular joint movements. Restoration of kinematic processing by cortical neurons in the course of post-traumatic period was characterized by facilitation of activatory reactions of the area 4 cortical cells to peripheral cutaneous stimulation. Some suggestions are made on the nature of plastic changes which develop in neuronal nets of the motor cortex after the lesion of n. VL.