Motor learning in patients with cerebellar dysfunction.

This study examined whether cerebellar dysfunction resulted in deficiencies of motor learning. Patients with cerebellar atrophy only or cerebellar atrophy combined with atrophy of the brainstem and age-matched normal subjects performed two tasks to assess improvements in skilled performance. The first task was repetitive tracing with the hand of an irregular geometric pattern with normal visual guidance, and the second task was repetitive tracing of a different geometric pattern with mirror-reversed vision. Patients with pathology limited to the cerebellum showed impairments in the skilled performance of the movement performed with normal vision that may have been related to a failure to alter movement strategy. Patients with added pathology in the brainstem exhibited impairments in adapting to mirror-reversed vision. Subsidiary experiments indicated that improvements of movements guided by mirror-reversed vision were mediated by vision. These results indicate that the cerebellum and its associated input pathways are involved in motor skill learning.