INTACT MIRROR-TRACING AND IMPAIRED ROTARY-PURSUIT SKILL LEARNING IN PATIENTS WITH HUNTINGTONS-DISEASE - EVIDENCE FOR DISSOCIABLE MEMORY-SYSTEMS IN SKILL LEARNING

Skill learning in early-stage Huntington's disease (HD) patients was c ompared with that of normal controls on 2 perceptual-motor tasks, rota ry pursuit and mirror tracing. HD patients demonstrated a dissociation between impaired rotary-pursuit and intact mirror-tracing skill learn ing. These results suggest that different forms of perceptual-motor sk ill learning are mediated by separable neural circuits. A striatal mem ory system may be essential for sequence or open-loop skill learning b ut not for skills that involve the closed-loop learning of novel visua l-response mappings. It is hypothesized that working memory deficits i n HD resulting from frontostriatal damage may account broadly for inta ct and impaired long-term learning and memory in HD patients.