About Sleep's Role in Memory

Björn Rasch, Jan Born
2013 Physiological Reviews  
Over more than a century of research has established the fact that sleep benefits the retention of memory. In this review we aim to comprehensively cover the field of "sleep and memory" research by providing a historical perspective on concepts and a discussion of more recent key findings. Whereas initial theories posed a passive role for sleep enhancing memories by protecting them from interfering stimuli, current theories highlight an active role for sleep in which memories undergo a process
more » ... f system consolidation during sleep. Whereas older research concentrated on the role of rapid-eye-movement (REM) sleep, recent work has revealed the importance of slow-wave sleep (SWS) for memory consolidation and also enlightened some of the underlying electrophysiological, neurochemical, and genetic mechanisms, as well as developmental aspects in these processes. Specifically, newer findings characterize sleep as a brain state optimizing memory consolidation, in opposition to the waking brain being optimized for encoding of memories. Consolidation originates from reactivation of recently encoded neuronal memory representations, which occur during SWS and transform respective representations for integration into long-term memory. Ensuing REM sleep may stabilize transformed memories. While elaborated with respect to hippocampus-dependent memories, the concept of an active redistribution of memory representations from networks serving as temporary store into long-term stores might hold also for non-hippocampus-dependent memory, and even for nonneuronal, i.e., immunological memories, giving rise to the idea that the offline consolidation of memory during sleep represents a principle of long-term memory formation established in quite different physiological systems. In 1885, Ebbinghaus, the father of experimental memory research, published a series of studies, on himself, about the BJÖRN RASCH AND JAN BORN after learning on memory for senseless syllables. Sleep after learning leads to superior recall of syllables after the 1-, 2-, 4-, and 8-h retention interval, compared with wake intervals of the same length. Two subjects (H. and Mc.) participated in this classic study by Jenkins and Dallenbach (603). For each data point, each participant completed 6 -8 trials, with the different retention intervals performed in random order. The study took ϳ2 mo during which the participants lived in the laboratory and were tested almost every day and night. Data are based on Table 3 in Reference 603, as the original figure contains an erroneous exchange of data points at the 4-h wake retention interval. Values are means Ϯ SE. **P Յ 0.01; ***P Յ 0.001. SLEEP AND MEMORY 685 Physiol Rev • VOL 93 • APRIL 2013 • www.prv.org Physiol Rev • VOL 93 • APRIL 2013 • www.prv.org on earlier versions of the manuscript. In particular, we thank Drs. Ted Abel, Igor Timofeev, and Paul Shaw for very constructive comments and corrections.
doi:10.1152/physrev.00032.2012 pmid:23589831 pmcid:PMC3768102 fatcat:hwyquoixznaofmhcrp2ipgixie