ELECTRICAL STIMULATION OF THE INTERIOR OF THE CEREBELLUM IN THE MONKEY

Abstract

Electrical stimulation of the interior of the cerebellum in the monkey, employing the Horsley-Clarke stereotaxic instrument, yielded responses which, with the possible exception of some reactions of conjugate deviation of the eyes and head to the side of stimulation, were biphasic, and consisted either of an inhibition of a muscle group during stimulation followed by a rebound contraction of this muscle group at the end of stimulus, or of a contraction of one muscle group during stimulation followed at the end of stimulus by a rebound contraction of its antagonist. Such reactions, involving small and short-lasting postures of the ipsilateral anterior extremity, were traced from the buried cortex of the anterior lobe through the underlying white matter to the region of the emboliform and globose nuclei. Other reactions of thia nature involving pronounced and long-lasting postures of all 4 limbs, the rebound contractions usually persisting for a period of minutes, were traced from the buried cortex of the anterior lobe through the underlying white matter to the region of the fastigial nucleus. Similar responses of the eyes, head and axial musculature, involving lateral deviations from the longi- tudinal body axis, were obtained from the white matter in the vicinity of the fastigial nucleus. Somewhat comparable reactions have been observed from cerebellar stimulation in the decerebrate preparation by a series of workers. The suggestion is made that such reactions simply represent normal cerebellar responses, the presence of a decerebrate rigidity being an incidental factor.