Neurological basis of skill learning.

Skill-learning, i.e., anterograde memory of 'procedures' has been separated from conventional declarative memory, or event- or data-related memory. This type of memory requires a concerted activity of various neural structures which are not assigned to the acquisition of declarative memory. We employed mirror reading task as a paradigm of skill acquisition memory and tried to elucidate possible neurological mechanisms involved in the procedural memory process. Ten normal control subjects, 10 early, non-treated Parkinson's, and 9 relatively early spinocerebellar degeneration patients participated in our study. The results showed a clear dissociation between declarative memory and mirror reading skill acquisition capacity. Thus, the Parkinson's patients as well as the spinocerebellar patients showed retardation in acquiring mirror reading skills, while both groups showed normal performance in auditory verbal learning tests and word recognition tests. The facts suggest a possible role of the nigro-striatal system and fronto-ponto-cerebellar system in forming these skill-related memory.