The dynamics of implicit skill consolidation in young and elderly adults

Objectives: Implicit skill learning underlies not only motor but 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-hour, a 24-hour and a 1-week interval. The task enabled us to separate the components of skill learning and consolidation: 1) general skill and 2) sequence-specific learning. Results: We found improvement of general skill for the young adults in all delay conditions. The elderly adults also showed enhancement after the 12-hour period, revealing brain plasticity similar to young adults. This improvement disappeared in the 24-hour and the 1-week delay conditions. Regarding sequence-specific learning, no improvement was found in either age group and at either consolidation interval. 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 which are differentially affected by time course and by aging