ON THE ROLE OF THE HUMAN CEREBELLUM IN MO TOR LEARNING

Results of recent studies using positron emission tomography (PFT) are presented demonstrating the involvement of the human cerebellum in si mple and complex motor learning tasks in cerebellar patients and in he althy subjects. Classical conditioning of the limb flexion reflex (ass ociative learning) and learning of sequences of single finger movement s (non-associative learning) were studied in healthy subjects using PE T. Different parts of the cerebellum were involved in the associative and non-associative learning paradigm suggesting functional compartmen talization of the human cerebellum for simple motor learning tasks. Ad aptation of postural responses to changing task conditions and a compl ex visuomotor learning task were investigated in a group of patients w ith cerebellar disease. Despite of their postural dysmetria, patients with cerebellar disease were able to adapt their postural synergies to changing task conditions and, to improve their performance of the com plex visuomotor task despite upper limb ataxia. These findings support the view that the role of the cerebellum in motor learning might be r estricted to motor performance and need not be linked to the establish ment of critical engrams assumed to be stored within this structure.