Sleep-dependent facilitation of episodic memory details

While a role for sleep in declarative memory processing is established, the qualitative nature of this consolidation benefit, and the physiological mechanisms mediating it, remain debated. Here, we investigate the impact of sleep physiology on characteristics of episodic memory using an item- (memor...

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Bibliographic Details
Published in:PloS one 2011-11, Vol.6 (11), p.e27421-e27421
Main Authors: van der Helm, Els, Gujar, Ninad, Nishida, Masaki, Walker, Matthew P
Format: Article
Language:English
Subjects:
Activity patterns
Adolescent
Adult
Biology
Coding
Consolidation
Female
Group dynamics
Hippocampus
Hippocampus - physiology
Humans
Judgments
Laboratories
Learning - physiology
Lists
Male
Medical imaging
Medicine
Memory
Memory, Episodic
Neurosciences
NMR
NREM sleep
Nuclear magnetic resonance
Oscillations
Physiological aspects
Physiology
Retention
Sleep
Sleep (NREM)
Sleep - physiology
Social and Behavioral Sciences
Studies
Temporal variations
Wakefulness - physiology
Young Adult
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Summary:While a role for sleep in declarative memory processing is established, the qualitative nature of this consolidation benefit, and the physiological mechanisms mediating it, remain debated. Here, we investigate the impact of sleep physiology on characteristics of episodic memory using an item- (memory elements) and context- (contextual details associated with those elements) learning paradigm; the latter being especially dependent on the hippocampus. Following back-to-back encoding of two word lists, each associated with a different context, participants were assigned to either a Nap-group, who obtained a 120-min nap, or a No Nap-group. Six hours post-encoding, participants performed a recognition test involving item-memory and context-memory judgments. In contrast to item-memory, which demonstrated no between-group differences, a significant benefit in context-memory developed in the Nap-group, the extent of which correlated both with the amount of stage-2 NREM sleep and frontal fast sleep-spindles. Furthermore, a difference was observed on the basis of word-list order, with the sleep benefit and associated physiological correlations being selective for the second word-list, learned last (most proximal to sleep). These findings suggest that sleep may preferentially benefit contextual (hippocampal-dependent) aspects of memory, supported by sleep-spindle oscillations, and that the temporal order of initial learning differentially determines subsequent offline consolidation.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0027421