A STUDY OF MOTOR-PERFORMANCE AND MOTOR LEARNING IN EPISODIC ATAXIA

EPISODIC ataxias are rare disorders in which periodic episodes of atax ia are separated by normal or near normal motor behaviour. They probab ly arise from dysfunctional membrane ion channels in the cerebellum. A patient with episodic ataxia EA-2 performed three motor tasks, before , during and after an ataxic episode. In all three tasks there were si gnificant performance deficits during the ataxic episode. Two of the t asks also assessed motor adaptation (prism adaptation) or motor learni ng (ideogram drawing). In neither task was there significant disruptio n of motor adaptation or learning. These results suggest that the cere bellum may have separate roles in learning and in performance of visua lly guided movements, and that the dysfunction in this patient affecte d only his motor performance.