Motor responses evoked by microstimulation of cerebellar interpositus nucleus in cats submitted to dorsal rhizotomy.

In cats with C4-T2 unilateral dorsal rhizotomy, stimulation of interpositus nucleus of the cerebellum, ipsilateral to the deafferented side, elicits in forelimbs single muscle contractions, which display threshold, latencies and spatial-temporal characteristics similar to those of the muscular responses produced in the other forelimb, upon stimulation of interpositus nucleus of the intact side. Motor effects induced by the interpositus nucleus-stimulation on the deafferented side disappear following red nucleus lesions. Single muscle contractions triggered from interpositus nucleus are, therefore, mediated by impulses impinging on alpha-motoneurons, via the rubrospinal pathway.