We have studies multi-joint arm movements in a patient with right cere
bellar damage. Our patient's kinetic tremor was reduced in the absence
of visual feedback, but increased when performing a concurrent cognit
ive task. We suggest that her kinetic tremor reflects use of a slow co
rtical feedback circuit for error-corrections during movement. Analysi
ng the spatial relation between hand aperture and hand transport in pr
ehensile movements, we found preserved strategic, trial-to-trial coord
ination, but impaired reactive, within-trial coordination. We conclude
that the proprioceptive representations provided by the normal cerebe
llum play an important role in coordinating multi-joint movement.