SPINAL TRACTS MEDIATING SUBTHALAMIC HYPERKINESIA: PHYSIOLOGICAL EFFECTS OF SELECTIVE PARTIAL CORDOTOMIES UPON DYSKINESIA IN RHESUS MONKEY

Abstract

Attempts were made to differentially section at high cervical levels the following portions of the spinal cord: (1): dorsal columns, (2) dorsal half of the lateral funicu-lus, and (3) the ventral quadrant. Choreoid hyperkinesia in the monkey produced by appropriate subthalamic lesions: (a) can be abolished, without later recrudescence, by section of the lateral corticospinal tract, (b) is not abolished by section of the ventral half of the lateral funiculus and the ventral funiculus, and (c) may be reduced in force, amplitude and violence by lesions involving parts of the dorsal half of the lateral funiculus. Impulses responsible for choreoid dyskinesia of this type in the monkey: (a) appear to be transmitted to segmental levels via the lateral corticospinal tracts, and (b) are not transmitted to segmental levels via the rubrospinal, vestibulospinal, or pontine and medullary reticulospinal tracts.