Oscillatory characterization of targeted memory reactivations during sleep:

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During non-rapid eye movement (NREM) sleep, spontaneous and repeated reactivations, or replay, of recently acquired information is thought to underlie the role of sleep for stabilization of memories. Re-exposure to learning associated material during NREM sleep can improve memory recall of the previously learned associations. However, memory reactivations also occur during wakefulness. In order to elucidate the role of reactivations during wakefulness and sleep and how these might be related to each other, we conducted an MEG study where cueing of words associated to previously learned word-picture associations took place either during wakefulness or during sleep. We found that cueing during both conditions benefited memory recall of cued stimuli in comparison to uncued ones, only after the sleep interval. Oscillatory activity related to successful cueing (i.e. remembered pictures associated with cued words) was characterized by increases in theta and spindle power after cue onset. Moreover, spindle power showed a lateralized pattern related to the presentation of the pictures during the learning phase. The present findings suggest that reactivation of memories during wakefulness might play a role for selecting newly encoded memory traces for further processing during sleep. The underlying mechanisms of successful reactivations during wakefulness and sleep might share to some extent similar patterns of activity that interact in both states in order to support the stabilization and integration of memories. Keywords: targeted memory reactivations, sleep, memory consolidation, MEG
Faculteit der Sociale Wetenschappen