Abstract
Procedural learning is a fundamental cognitive function that facilitates efficient processing of and automatic responses to environmental stimuli. Here, we examined training-dependent and off-line changes of two sub-processes of procedural learning: namely, sequence learning (acquisition of order-based associations) and statistical learning (acquisition of frequency-based associations). Healthy young adults completed a procedural learning task, and were retested after a delay containing either active wakefulness, quiet rest, or daytime sleep. Performance in Sequence Learning increased gradually during training and during additional practice after the delay, while Statistical Learning plateaued early. Although, on a behavioral level, Sequence and Statistical Learning were similar across groups after the delay, cortical oscillations were associated with performance within the sleep group only. Moreover, sleep spindle parameters showed differential associations with Sequence and Statistical Learning. Our findings can contribute to a deeper understanding of the dynamic changes of parallel learning and consolidation processes that underlie procedural memory formation.