Cued memory reactivation during sleep influences skill learning

Abstract

Information acquired during waking can be reactivated during sleep, promoting memory stabilization. After people learned to produce two melodies in time with moving visual symbols, we enhanced relative performance by presenting one melody during an afternoon nap. Electrophysiological signs of memory processing during sleep corroborated the notion that appropriate auditory stimulation that does not disrupt sleep can nevertheless bias memory consolidation in relevant brain circuitry.

Figure 1

Methods and behavioral results. (a) Subjects learned to play melodies with four fingers of the left hand while watching circles that indicated which key to press when. Circles ascended at 10.8 cm/s toward four stationary targets (dashed yellow outlines). After initial learning trials, the amount of advance information was reduced using an opaque mask (shown here as transparent). Two melodies were repeatedly practiced (red and blue). Baseline melodies (green) were played during testing periods before and after the nap. Either the high melody (8 subjects) or the low melody (8 subjects) was presented covertly (cued) during sleep. (b) Accuracy scores (percent correct responses) were computed according to whether the correct key was pressed at the proper time. Differences were analyzed using two-tailed paired t-tests (N=16; * = P<0.05; ** = P<0.005). Error bars show standard errors of the mean in each condition after removing across-subject variability (i.e., subtracting the mean across all conditions for each individual), which provides variability estimates in agreement with the error terms used in the critical within-subject comparisons.

Figure 2

Sleep cues and physiology. Reactivation advantage was correlated with percentage of time in SWS (a, N=14, Pearson correlation, r=0.60, P=0.02), and with number of sleep spindles during SWS at the F4 location (b, r=0.74, P=0.002). Spindle correlation values, shown with a color scale on a topographic map of the head viewed from above (c), were largest over cortical regions contralateral to the hand used to perform the melodies.