ARTICLE CRITIQUE

Article Critique

Article Critique

Background

Sleep is widely believed to play a critical role in memory consolidation. Sleep-dependent consolidation has been studied extensively in humans using an explicit motor-sequence learning paradigm. In this task, performance has been reported to remain stable across wakefulness and improve significantly after sleep, making motor-sequence learning the definitive example of sleep-dependent enhancement. Recent work, however, has shown that enhancement disappears when the task is modified to reduce task-related inhibition that develops over a training session, thus questioning whether sleep actively consolidates motor learning.

Here we use the same motor-sequence task to demonstrate sleep-dependent consolidation for motor-sequence learning and explain the discrepancies in results across studies. The previous study attempts to reconcile the ?nding of negative fatigue results with positive sleep results by investigating explicit and implicit motor learning in a single task. To do this, we manipulated three factors. First, we varied target patterns between an explicit, repeating pattern and an implicit, non-repeating pattern. Second, to examine fatigue, we tested amassed condition (based on Maquet et al. and a spaced condition. Lastly, we compared napping to a quiet rest control group to eliminate circadian confounds and the possible negative effects of sleep deprivation, waking interference, on-task fatigue, or uncontrolled forms of inhibition in the non-sleep group.

We hypothesized that the explicit, repeating target pattern would show a between session bene?t driven by fatigue in the ?rst session rather than sleep. Second, we hypothesized that spacing practice in the explicit pattern condition would eliminate both massed practice fatigue and the between session performance increases previously ascribed to sleep-dependent processes. Third, we hypothesized that improvements in the implicit, non-repeating target pattern would be sleep-dependent, not observed in the quiet rest group, and independent of both massed and spaced learning. Results were obtained from a cohort of 81 participants. Forty seven participants (28 and 19 in the napping and quiet ...