Fig. 1: Skill learning task and behavioral performance.

Panel a Participants learned the motor-skill task consisting of alternating practice and rest periods of 10 s duration for a total of 36 blocks. In each practice task block, participants were asked to repeatedly tap the sequence 4-1-3-2-4 as quickly and accurately as possible using their left, non-dominant hand. Practice task blocks were interleaved with 10-s waking rest intervals (inter-practice rest). Note that motor learning performance increases occur during the intervening periods of waking rest (micro-offline gains), but not during the active practice task (micro-online learning). Panel b Mean performance of all participants. Skill was measured as the correct sequence typing speed (sequences [seq]/s). Mean average performance (mean ± SEM) increased rapidly during early learning (the set of trials within which 95% of total learning occurred, trials 1–11 (left panel) extracted by means of the curve fitting performance (right panel). The vertical black line in the right panel corresponds to the block T where 95% of total learning occurred. Micro-online changes were calculated as the difference in tapping speed (keypresses/s) between the first and last correct sequence within a practice period (black in inset) and micro-offline changes as the difference between the last correct sequence within a practice period and the first of the next practice period (red in inset).