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Replay of conditioned stimuli during late REM and stage N2 sleep influences affective tone rather than emotional memory strength


Rihm, Julia S; Rasch, Björn (2015). Replay of conditioned stimuli during late REM and stage N2 sleep influences affective tone rather than emotional memory strength. Neurobiology of Learning and Memory, 122:142-151.

Abstract

Emotional memories are reprocessed during sleep, and it is widely assumed that this reprocessing occurs mainly during rapid eye movement (REM) sleep. In support for this notion, vivid emotional dreams occur mainly during REM sleep, and several studies have reported emotional memory enhancement to be associated with REM sleep or REM sleep-related parameters. However, it is still unknown whether reactivation of emotional memories during REM sleep strengthens emotional memories. Here, we tested whether re-presentation of emotionally learned stimuli during REM sleep enhances emotional memory. In a split-night design, participants underwent Pavlovian conditioning after the first half of the night. Neutral sounds served as conditioned stimuli (CS) and were either paired with a negative odor (CS+) or an odorless vehicle (CS-). During sound replay in subsequent late REM or N2 sleep, half of the CS+ and half of the CS- were presented again. In contrast to our hypothesis, replay during sleep did not affect emotional memory as measured by the differentiation between CS+ and CS- in expectancy, arousal and valence ratings. However, replay unspecifically decreased subjective arousal ratings of both emotional and neutral sounds and increased positive valence ratings also for both CS+ and CS- sounds, respectively. These effects were slightly more pronounced for replay during REM sleep. Our results suggest that re-exposure to previously conditioned stimuli during late sleep does not affect emotional memory strength, but rather influences the affective tone of both emotional and neutral memories.

Abstract

Emotional memories are reprocessed during sleep, and it is widely assumed that this reprocessing occurs mainly during rapid eye movement (REM) sleep. In support for this notion, vivid emotional dreams occur mainly during REM sleep, and several studies have reported emotional memory enhancement to be associated with REM sleep or REM sleep-related parameters. However, it is still unknown whether reactivation of emotional memories during REM sleep strengthens emotional memories. Here, we tested whether re-presentation of emotionally learned stimuli during REM sleep enhances emotional memory. In a split-night design, participants underwent Pavlovian conditioning after the first half of the night. Neutral sounds served as conditioned stimuli (CS) and were either paired with a negative odor (CS+) or an odorless vehicle (CS-). During sound replay in subsequent late REM or N2 sleep, half of the CS+ and half of the CS- were presented again. In contrast to our hypothesis, replay during sleep did not affect emotional memory as measured by the differentiation between CS+ and CS- in expectancy, arousal and valence ratings. However, replay unspecifically decreased subjective arousal ratings of both emotional and neutral sounds and increased positive valence ratings also for both CS+ and CS- sounds, respectively. These effects were slightly more pronounced for replay during REM sleep. Our results suggest that re-exposure to previously conditioned stimuli during late sleep does not affect emotional memory strength, but rather influences the affective tone of both emotional and neutral memories.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:06 Faculty of Arts > Institute of Psychology
Dewey Decimal Classification:150 Psychology
Uncontrolled Keywords:DoktoratPSych Erstautor
Date:July 2015
Deposited On:21 Jun 2016 11:37
Last Modified:22 Jun 2016 07:55
Publisher:Elsevier
ISSN:1074-7427
Publisher DOI:https://doi.org/10.1016/j.nlm.2015.04.008
PubMed ID:25933506

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