DIFFERENTIAL ROLES OF MONKEY STRIATUM IN LEARNING OF SEQUENTIAL HAND MOVEMENT

To study the role of the basal ganglia in learning of sequential movem ents, we trained two monkeys to perform a sequential button-press task (2x5 task). This task enabled us to examine the process of learning n ew sequences as well as the execution of well-learned sequences repeat edly. We injected muscimol (a GABA agonist) into different parts of th e striatum to inactivate the local neural activity reversibly. The lea rning of new sequences became deficient after injections in the anteri or caudate and putamen, but not the middle-posterior putamen. The exec ution of well-learned sequences was disrupted after injections in the middle-posterior putamen and, less severely, after injections in the a nterior caudate/putamen. These results suggest that the anterior and p osterior portions of the striatum participate in different aspects of learning of sequential movements.