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No effect of odor-induced memory reactivation during REM sleep on declarative memory stability.

Cordi MJ, Diekelmann S, Born J, Rasch B - Front Syst Neurosci (2014)

Bottom Line: In humans, experimentally inducing hippocampal memory reactivations during slow-wave sleep (but not during wakefulness) benefits consolidation and immediately stabilizes declarative memories against future interference.We show that odor-induced memory reactivation during REM sleep does not stabilize memories against future interference.We propose that the beneficial effect of reactivation during sleep on memory stability might be critically linked to processes characterizing SWS including, e.g., slow oscillatory activity, sleep spindles, or low cholinergic tone, which are required for a successful redistribution of memories from medial temporal lobe regions to neocortical long-term stores.

View Article: PubMed Central - PubMed

Affiliation: Division of Biopsychology, Institute of Psychology, University of Zurich Zurich, Switzerland.

ABSTRACT
Memory reactivations in hippocampal brain areas are critically involved in memory consolidation processes during sleep. In particular, specific firing patterns of hippocampal place cells observed during learning are replayed during subsequent sleep and rest in rodents. In humans, experimentally inducing hippocampal memory reactivations during slow-wave sleep (but not during wakefulness) benefits consolidation and immediately stabilizes declarative memories against future interference. Importantly, spontaneous hippocampal replay activity can also be observed during rapid eye movement (REM) sleep and some authors have suggested that replay during REM sleep is related to processes of memory consolidation. However, the functional role of reactivations during REM sleep for memory stability is still unclear. Here, we reactivated memories during REM sleep and examined its consequences for the stability of declarative memories. After 3 h of early, slow-wave sleep (SWS) rich sleep, 16 healthy young adults learned a 2-D object location task in the presence of a contextual odor. During subsequent REM sleep, participants were either re-exposed to the odor or to an odorless vehicle, in a counterbalanced within subject design. Reactivation was followed by an interference learning task to probe memory stability after awakening. We show that odor-induced memory reactivation during REM sleep does not stabilize memories against future interference. We propose that the beneficial effect of reactivation during sleep on memory stability might be critically linked to processes characterizing SWS including, e.g., slow oscillatory activity, sleep spindles, or low cholinergic tone, which are required for a successful redistribution of memories from medial temporal lobe regions to neocortical long-term stores.

No MeSH data available.


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Recall of card locations (%) was not differentially affected by interference learning after reactivation in REM sleep (A), but showed impairments after reactivation during wakefulness and enhanced resistance toward interference after reactivation in SWS (B, data adapted from Diekelmann et al., 2011). Values are means ± s.e.m.
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Figure 2: Recall of card locations (%) was not differentially affected by interference learning after reactivation in REM sleep (A), but showed impairments after reactivation during wakefulness and enhanced resistance toward interference after reactivation in SWS (B, data adapted from Diekelmann et al., 2011). Values are means ± s.e.m.

Mentions: In contrast to the hypothesis of the beneficial role of memory reactivations during REM sleep, inducing reactivations during REM sleep had no influence on memory stability. After odor-induced memory reactivation during REM sleep, participants remembered 54.16 ± 5.93% of the learned locations, whereas they correctly recalled 52.86 ± 6.49% after presentation of the odorless vehicle stimulus (p = 0.87, Figure 2A and Table 1). Learning performance (number of recalled card pairs at the end of learning) did not differ significantly between the two conditions (9.92 ± 0.26 vs. 10.69 ± 0.37, p = 0.13) and learning of the interference task was also highly comparable (6.07 ± 0.83 vs. 5.67 ± 0.82, p = 0.72).


No effect of odor-induced memory reactivation during REM sleep on declarative memory stability.

Cordi MJ, Diekelmann S, Born J, Rasch B - Front Syst Neurosci (2014)

Recall of card locations (%) was not differentially affected by interference learning after reactivation in REM sleep (A), but showed impairments after reactivation during wakefulness and enhanced resistance toward interference after reactivation in SWS (B, data adapted from Diekelmann et al., 2011). Values are means ± s.e.m.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150443&req=5

Figure 2: Recall of card locations (%) was not differentially affected by interference learning after reactivation in REM sleep (A), but showed impairments after reactivation during wakefulness and enhanced resistance toward interference after reactivation in SWS (B, data adapted from Diekelmann et al., 2011). Values are means ± s.e.m.
Mentions: In contrast to the hypothesis of the beneficial role of memory reactivations during REM sleep, inducing reactivations during REM sleep had no influence on memory stability. After odor-induced memory reactivation during REM sleep, participants remembered 54.16 ± 5.93% of the learned locations, whereas they correctly recalled 52.86 ± 6.49% after presentation of the odorless vehicle stimulus (p = 0.87, Figure 2A and Table 1). Learning performance (number of recalled card pairs at the end of learning) did not differ significantly between the two conditions (9.92 ± 0.26 vs. 10.69 ± 0.37, p = 0.13) and learning of the interference task was also highly comparable (6.07 ± 0.83 vs. 5.67 ± 0.82, p = 0.72).

Bottom Line: In humans, experimentally inducing hippocampal memory reactivations during slow-wave sleep (but not during wakefulness) benefits consolidation and immediately stabilizes declarative memories against future interference.We show that odor-induced memory reactivation during REM sleep does not stabilize memories against future interference.We propose that the beneficial effect of reactivation during sleep on memory stability might be critically linked to processes characterizing SWS including, e.g., slow oscillatory activity, sleep spindles, or low cholinergic tone, which are required for a successful redistribution of memories from medial temporal lobe regions to neocortical long-term stores.

View Article: PubMed Central - PubMed

Affiliation: Division of Biopsychology, Institute of Psychology, University of Zurich Zurich, Switzerland.

ABSTRACT
Memory reactivations in hippocampal brain areas are critically involved in memory consolidation processes during sleep. In particular, specific firing patterns of hippocampal place cells observed during learning are replayed during subsequent sleep and rest in rodents. In humans, experimentally inducing hippocampal memory reactivations during slow-wave sleep (but not during wakefulness) benefits consolidation and immediately stabilizes declarative memories against future interference. Importantly, spontaneous hippocampal replay activity can also be observed during rapid eye movement (REM) sleep and some authors have suggested that replay during REM sleep is related to processes of memory consolidation. However, the functional role of reactivations during REM sleep for memory stability is still unclear. Here, we reactivated memories during REM sleep and examined its consequences for the stability of declarative memories. After 3 h of early, slow-wave sleep (SWS) rich sleep, 16 healthy young adults learned a 2-D object location task in the presence of a contextual odor. During subsequent REM sleep, participants were either re-exposed to the odor or to an odorless vehicle, in a counterbalanced within subject design. Reactivation was followed by an interference learning task to probe memory stability after awakening. We show that odor-induced memory reactivation during REM sleep does not stabilize memories against future interference. We propose that the beneficial effect of reactivation during sleep on memory stability might be critically linked to processes characterizing SWS including, e.g., slow oscillatory activity, sleep spindles, or low cholinergic tone, which are required for a successful redistribution of memories from medial temporal lobe regions to neocortical long-term stores.

No MeSH data available.


Related in: MedlinePlus