Rihm Julia S, Rasch Björn
Department of Psychology, Division of Biopsychology, University of Zurich, Zurich, Switzerland; Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Department of Psychology, University of Fribourg, Fribourg, Switzerland; Zurich Center for Interdisciplinary Sleep Research (ZiS), Zurich, Switzerland.
Neurobiol Learn Mem. 2015 Jul;122:142-51. doi: 10.1016/j.nlm.2015.04.008. Epub 2015 Apr 28.
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.
情绪记忆在睡眠期间会被重新处理，人们普遍认为这种重新处理主要发生在快速眼动（REM）睡眠期间。支持这一观点的是，生动的情绪梦主要发生在REM睡眠期间，并且多项研究报告称情绪记忆增强与REM睡眠或REM睡眠相关参数有关。然而，REM睡眠期间情绪记忆的重新激活是否会强化情绪记忆仍不清楚。在此，我们测试了在REM睡眠期间重新呈现情感学习刺激是否会增强情绪记忆。在一项分夜设计中，参与者在上半夜后接受巴甫洛夫条件反射训练。中性声音作为条件刺激（CS），与负面气味（CS+）或无味载体（CS-）配对。在随后的REM晚期或N2睡眠中声音重放期间，一半的CS+和一半的CS-再次呈现。与我们的假设相反，睡眠期间的重放并未影响情绪记忆，这通过CS+和CS-在预期、唤醒和效价评分方面的差异来衡量。然而，重放非特异性地降低了情绪和中性声音的主观唤醒评分，并且分别提高了CS+和CS-声音的正性效价评分。这些效应在REM睡眠期间的重放中更为明显。我们的结果表明，在睡眠后期重新暴露于先前的条件刺激不会影响情绪记忆强度，而是会影响情绪和中性记忆的情感基调。
