Robertson Edwin M, Pascual-Leone Alvaro, Press Daniel Z
Laboratory for Magnetic Brain Stimulation, Behavioral Neurology Unit, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, USA.
Curr Biol. 2004 Feb 3;14(3):208-12. doi: 10.1016/j.cub.2004.01.027.
Behind every skilled movement lies months of practice. However, practice alone is not responsible for the acquisition of all skill; performance can improve between, not just within, practice sessions. An important principle shaping these offline improvements may be an individual's awareness of learning a new skill. New skills, such as a sequence of finger movements, can be learned unintentionally (with little awareness for the sequence, implicit learning) or intentionally (explicit learning). We measured skill in an implicit and explicit sequence-learning task before and after a 12 hr interval. This interval either did (8 p.m. to 8 a.m.) or did not (8 a.m. to 8 p.m.) include a period of sleep. Following explicit sequence learning, offline skill improvements were only observed when the 12 hr interval included sleep. This overnight improvement was correlated with the amount of NREM sleep. The same improvement could also be observed in the evening (with an interval from 8 p.m. to 8 p.m.), so it was not coupled to retesting at a particular time of day and cannot therefore be attributed to circadian factors. In contrast, in the implicit learning task, offline learning was observed regardless of whether the 12 hr interval did or did not contain a period of sleep. However, these improvements were not observed with only a 15 min interval between sessions. Therefore, the practice available within each session cannot account for these skill improvements. Instead, sufficient time is necessary for offline learning to occur. These results show a behavioral dissociation, based upon an individual's awareness for having learned a sequence of finger movements. Offline learning is sleep dependent for explicit skills but time dependent for implicit skills.
每一项熟练的动作背后都有数月的练习。然而，仅仅练习并不能促成所有技能的习得；表现不仅在练习期间会提高，在练习之间也会提高。塑造这些离线提高的一个重要原则可能是个体对学习新技能的意识。新技能，比如一系列手指动作，可以无意地（对动作序列几乎没有意识，即内隐学习）或有意地（外显学习）习得。我们在一个内隐和外显序列学习任务中，在12小时的间隔前后测量了技能。这个间隔要么包含（晚上8点到早上8点）要么不包含（早上8点到晚上8点）一段睡眠期。在外显序列学习之后，只有当12小时的间隔包含睡眠时，才会观察到离线技能提高。这种夜间提高与非快速眼动睡眠量相关。同样的提高在晚上（从晚上8点到晚上8点的间隔）也能观察到，所以它与在一天中的特定时间重新测试无关，因此不能归因于昼夜节律因素。相比之下，在内隐学习任务中，无论12小时的间隔是否包含一段睡眠期，都能观察到离线学习。然而，在各次练习之间只有15分钟的间隔时，并没有观察到这些提高。因此，每次练习中的可用练习不能解释这些技能提高。相反，离线学习需要足够的时间才能发生。这些结果显示了一种行为上的分离，其依据是个体对学习了一系列手指动作的意识。离线学习对于外显技能依赖于睡眠，而对于内隐技能依赖于时间。
