The current study explores the effects of time and sleep on the consolidation of a novel language learning task containing both item-specific knowledge and the extraction of grammatical regularities. We also compare consolidation effects in language and motor sequence learning tasks, to ask whether consolidation mechanisms are domain general. Young adults learned to apply plural inflections to novel words based on morpho-phonological rules embedded in the input and learned to type a motor sequence using a keyboard. Participants were randomly assigned into one of two groups, practicing each task during the morning or evening hours. Both groups were retested 12 and 24 hrs. post training. Performance on frequent trained items in the language task stabilized only following sleep, consistent with a hippocampal mechanism for item-specific learning. However, regularity extraction, indicated by generalization to untrained items in the linguistic task, as well as performance on motor sequence learning, improved 24 hours post training, irrespective of the timing of sleep. This consolidation process is consistent with a fronto-striatal skill learning mechanism, common across the language and motor domains. This conclusion is further reinforced by cross domain correlations at the individual level between improvement across 24 hours in the motor task and in the low-frequency trained items in the linguistic task, which involve regularity extraction. Taken together, our results at the group and individual levels suggest that some aspects of consolidation are shared across the motor and language domains, and more specifically between motor sequence learning and grammar learning.

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