DESCRIPTION (from applicant's abstract) The major goals of this project are to study the possible role of the cerebellum in learning and storing different aspects of movement including compensation for interaction torques, eye-hand coordination, and movements made with delayed results (error feedback). One project (in normal humans and cerebellar patients) asks whether the cerebellum is involved in learning to compensate for interaction torques generated in multi-segmented limb movements. Subjects make multi joint movements of novel trajectory and novel interaction torque loading. Their ability to adapt is measured using video-based motion analysis. Simple movements are monitored as controls. A second project (in monkey) asks whether relative positions of eye-head-trunk-arm in three previously learned gaze-reach combinations are stored in cerebellar cortex. Unit recording in trained animals will determine if behavioral variables are combined in Purkinje cell discharge. Muscimol microinjection will determine if the learned gaze-reach combinations are lost after cerebellar cortical inactivation. A third project (in monkey) examines the role of the cerebellum in learning to reach to a displaced visual target despite a delay in the error feedback information. Unit recording and muscimol inactivation will determine if "clinically silent" portions of the inferior-lateral posterior lobe cerebellar cortex are involved in and necessary for this adjustment. Each project will bring a different kind of new information to bear on the question of how normal subjects learn coordinated movement patterns and how patients with injuries of the nervous system may be helped to move more effectively.