Organization of the convergence in the intermediate cerebellar nuclei of somatosensory receptive fields with motor cortical-evoked responses.

The convergence in the intermediate cerebellar nuclei of somatosensory inputs with those from the motor cortex was investigated in cats (1) by examining with natural stimulation the receptive field of nuclear neurons, and (2) by determining the response of the same neurons to stimulation of motor cortical sites which had been identified by microstimulation-evoked movements. Of 196 neurons studied, a response to natural stimulation could be identified in 143, more than half of which (83) were driven by passive movement of one or two joints. The predominant response to cortical microstimulation was a suppression of discharge, although the suppression was sometimes preceded by a weak facilitation or interrupted by a brief but strong facilitation. A pattern of convergence was identified in which 72% of those cells driven by passive joint movement in one direction were suppressed by stimulation of the cortical site from which movement could be evoked in the opposite direction. A model based on this convergence is proposed.