The dynamics of implicit skill consolidation in young and elderly adults.

OBJECTIVES Implicit skill learning underlies not only motor but also cognitive and social skills; it is therefore an important aspect of life from infancy to old age. We studied aging effects on the time course of implicit skill consolidation. METHODS Young and elderly adults performed a probabilistic implicit sequence-learning task before and after a 12-, a 24-hr, and a 1-week interval. The task enabled us to separate the components of skill learning and consolidation: (a) general skill and (b) sequence-specific learning (SSL). RESULTS We found improvement of general skill for the young adults in all delay conditions. The elderly adults also showed enhancement after the 12-hr period, revealing brain plasticity similar to young adults. This improvement disappeared in the 24-hr and the 1-week delay conditions. Regarding SSL, no improvement was found in either age group and at either consolidation intervals. In contrast, sequences-specific knowledge decreased in the elderly group independently of the delay. DISCUSSION These results draw attention to the fact that consolidation is not a single process, rather there are multiple mechanisms that are differentially affected by time course and by aging.