Rem and Nrem Sleep Contributions in Memory for Verbal Material

1875 Scrima’s Hypothesis Revisited—Deliens et al INTRODUCTION A positive contribution of post-learning sleep in the consolidation of new information in long-term memory is now widely recognized.1-7 Beneficial effects of post-learning sleep have been highlighted for various memory systems, such as verbal declarative memory,8,9 emotional memory,10,11 or spatial learning,12 and non-declarative motor procedural learning13 or priming.14 Like long-term memory, sleep is not a unitary process but comprises different subsystems.15,16 In humans, it is characterized by two prominent stages, rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. NREM is further subdivided17 into stage 1 (N1), stage 2 (N2) and slow wave sleep (SWS or N3). Sleep stages, like memory subsystems, are differentiable at neuroanatomical, neurophysiological, and behavioral levels.3,18 Notwithstanding, how sleep stages specifically contribute to the consolidation of different memory types remains a matter of debate. REM AND NREM SLEEP CONTRIBUTIONS IN MEMORY FOR VERBAL MATERIAL