Basal ganglia cooling disables learned arm movements of monkeys in the absence of visual guidance.

Unilateral local cooling in the region of the globus pallidus of Cebus monkeys produced a severe breakdown in the performance of learned flexion-extension elbow movements when animals had no visual information about arm position but not when such information was displayed to them. This result indicates that visual information enables an animal to compensate to a large degree for the motor disorder produced by globus pallidus dysfunction, and it may explain why some previous workers have failed to see motor impairments in monkeys with lesions in the globus pallidus who were observed in their cages.