SPINAL PATHWAYS MEDIATING CEREBELLAR DYSKINESIA IN RHESUS MONKEY

Abstract

A study was made to determine the physiological effects of selective partial cordo-tomies upon cerebellar dyskinesia in the monkey produced by lesions in the deep cerebellar nuclei. Differential cordotomies at high cervical levels included: (1) ventral half of the lateral funiculus and the ventral funiculus, (2) dorsal columns, and (3) dorsal half of the lateral funiculus. Physiological observations were made after cerebellar and spinal surgery. Sections of the brains and spinal cord were stained by Nissal, Mahon and Marchi techniques. Cerebellar dyskinesia in the monkey produced by lesions in the deep cerebellar nuclei: (1) can be abolished without later recrudescence by section of the dorsal half of the lateral funiculus, (2) is not abolished by section of the ventral half of the lateral funiculus and the ventral funiculus, and (3) may be exaggerated by bilateral section of the posterior columns of the spinal cord. Impulses essential to the mechanism of cerebellar dyskinesia in the monkey are not transmitted to segmental levels via: (1) the rubrospinal tract, (2) the vestibulospinal tract or (3) the pontine or medullary reticulospinal tracts. Impulses concerned with the neural mechanism of cerebellar dyskinesia in the monkey provoked by lesions in the deep cerebellar nuclei appears to be transmitted to segmental levels via the lateral corticospinal tract.