Selective REM-Sleep Deprivation Does Not Diminish Emotional Memory Consolidation in Young Healthy Subjects

Abstract

Sleep enhances memory consolidation and it has been hypothesized that rapid eye movement (REM) sleep in particular facilitates the consolidation of emotional memory. The aim of this study was to investigate this hypothesis using selective REM-sleep deprivation. We used a recognition memory task in which participants were shown negative and neutral pictures. Participants (N = 29 healthy medical students) were separated into two groups (undisturbed sleep and selective REM-sleep deprived). Both groups also worked on the memory task in a wake condition. Recognition accuracy was significantly better for negative than for neutral stimuli and better after the sleep than the wake condition. There was, however, no difference in the recognition accuracy (neutral and emotional) between the groups. In summary, our data suggest that REM-sleep deprivation was successful and that the resulting reduction of REM-sleep had no influence on memory consolidation whatsoever.

Sleep selectively stabilizes contextual aspects of negative memories

“…As noted above, this is consistent with several studies reporting no effect of sleep on recognition memory 11,12 or familiarity-based recognition 46,47 . However, this contrasts with reports showing enhanced overall 19,29 or negative 15,17,[23][24][25] item recognition after sleep, in some cases relating these effects to REM sleep 17,[23][24][25] . Given the many differences in experimental design between these studies and ours, it remains to be seen under what conditions recognition metrics are sensitive to sleep-mediated consolidation processes.…”

“…Some evidence suggests that sleep and emotion interact, with enhanced retention of negative relative to neutral material following sleep [14][15][16][17] , although other studies have failed to find such an effect [18][19][20][21][22] . Furthermore, while several examinations into the contributions of specific sleep stages to emotional memory consolidation have emphasized the importance of rapid-eye movement (REM) sleep 17,[23][24][25] , others point to a role for non-rapid eye movement (NREM) sleep [26][27][28] , or find no clear stage dependence 20,[29][30][31] . These inconsistencies may be related to various experimental design factors (e.g., sleep vs. wake; full night vs. nap, split-night; sleep-deprivation; targeted memory reactivation), as well as the memory paradigm employed.…”

Slow wave and REM sleep deprivation effects on explicit and implicit memory during sleep.

“…While it has been claimed Vertes & Eastman, 2000) that the split-night design is advantageous over the deprivation of a sleep stage (or stages) throughout the night, which might induce a stress response, Morgenthaler, Wiesner, Hinze, et al (2014) found that morning self-evaluations of stress-influenced emotional and arousal states did not differ between selective REM deprivation and undisturbed sleep groups. Similarly, Genzel et al (2009) found that selective SWS or REM sleep deprivation throughout the night did not affect measures of concentration and stress.…”

Alpha Oscillations Prior to Encoding Preferentially Modulate Memory Consolidation during Wake Relative to Sleep

“…This enhancement is thought to be facilitated by REM theta oscillations which represent homeostatic processes of emotional brain regulation and have been linked to the synchronisation of emotional information between the amygdala and hippocampus, regions involved in emotional long-term memory (Diekelmann et al, 2009;Hutchison & Rathore, 2015;Prehn-Kristensen et al, 2013). However, recent findings suggest REM neurophysiology does not solely explain emotional memory consolidation (Morgenthaler et al, 2014). Alternatively, slow-wave sleep (SWS) is thought to facilitate the consolidation of emotional information through decreasing synaptic connectivity, ultimately pruning unnecessary neural connections and thus refining memory representations (Morgenthaler et al, 2014;Payne et al, 2015;Walker, 2010).…”

“…However, recent findings suggest REM neurophysiology does not solely explain emotional memory consolidation (Morgenthaler et al, 2014). Alternatively, slow-wave sleep (SWS) is thought to facilitate the consolidation of emotional information through decreasing synaptic connectivity, ultimately pruning unnecessary neural connections and thus refining memory representations (Morgenthaler et al, 2014;Payne et al, 2015;Walker, 2010). As such, it is possible that both SWS oscillations and REM theta oscillations are important for the consolidation of emotional memory (Cunningham, Chambers & Payne, 2014;Hutchison & Rathore, 2015).…”