FUNCTIONAL-ANATOMY OF VISUOMOTOR SKILL LEARNING IN HUMAN-SUBJECTS EXAMINED WITH POSITRON EMISSION TOMOGRAPHY

The present study was designed to examine patterns of regional cerebra l blood flow (CBF) associated with the learning of a repeated visuomot or sequence both in the early and late phases of the acquisition proce ss. In addition, changes in blood Row related to the implicit versus e xplicit aspects of learning such a skill were investigated. Fourteen n ormal control subjects were scanned while performing the task (i) in b oth early and advanced]earning stages of the visuomotor sequence; (ii) after having acquired explicit knowledge of the sequences; and (iii) in two control conditions (perceptual and random sequence), Subtractio n of the random condition from the highly learned condition revealed s pecific areas of activity in the right ventral striatum and dentate nu cleus of the cerebellum. Blood flow changes in the right hemisphere we re also seen in the medial posterior parietal and prestriate regions, as well as in the anterior cingulate cortex. Finally, once the subject s had acquired explicit knowledge of the embedded sequence that was pr esented in the highly learned condition, increased CBF activity was ob served only in the mid-ventrolateral frontal area in the right hemisph ere, These findings confirm that both the striatum and the cerebellum are involved in the implicit acquisition of a visuomotor skill, especi ally in the advanced stages of the learning process, and furthermore t hat the ventrolateral prefrontal cortex contributes preferentially to the declarative aspect of this task.