Examining the effects of post-learning sleep on consolidation of emotional declarative memories 公开

Abstract

Considerable research suggests that sleep can enhance the consolidation. Notably, the enhancing effects of emotion on memory have also been linked to enhanced memory consolidation, and specifically to hippocampal-dependent consolidation processes proposed to occur during sleep. However, this has only been investigated for negatively arousing memories and the effects of valence is currently unknown. An additional essential feature of declarative memories is the ability to bind different attributes of an event together and maintain these associations. Previous studies suggest sleep plays a key role in strengthening these associations, and this facilitation may be greater for emotionally salient stimuli than for emotionally neutral stimuli. However, it remains unclear whether post-learning sleep preferentially boosts emotional associations relative to neutral associations, in a similar way that it boosts memory for emotionally arousing single items. Using recognition and cued recall memory tasks, we examined whether sleep preferentially enhanced memory for positive and negative pictures (item memory) and negatively arousing verbal paired associates (associate memory) over neutral pictures and word pairs. Participants studied both emotional (positive and negative) and neutral pictures, and emotional (negative) and neutral verbal paired associates. Following a 12-hour break filled with either a period of sleep or wakefulness, participants were given surprise cued-recall (for the word pairs) and a recognition tasks (for the pictures). As prominent theories suggest that emotion enhances event memory during consolidation, via the modulatory effect of the amygdala on medial temporal lobe regions, retrieval of emotional items (relative to neutral ones) was expected to be preferentially enhanced after post-learning sleep. Results indicated that post-learning sleep did not enhance recognition memory performance, possibly due to ceiling effects in memory performance. Our results for cued-recall performance confirmed established literature that sleep enhances associative memory. However, the effect of sleep was equivalent for negative and neutral pairs, rather than disproportionately enhancing memory for negative pairs. Our results suggest the enhancing effect of sleep on paired-associate cued recall is independent of the emotional arousal of target items. These results contrast with previous findings and indicate the effects of sleep on memory for emotional material can differ substantially across different memory tasks.

Table of Contents

SLEEP AND EMOTIONAL MEMORY CONSOLIDATION

Table of Contents

Page
Introduction: General background……………………………………………………...................1

Theories on sleep and declarative memory consolidation……………...3

Emotion and declarative memory consolidation……………………….......7

Interactions between sleep and emotion………………………………..........8

Methods: Participants…………………………………………………………….......................13

Materials…………………………………………………………….........................…14

Procedure……………......................………………………………………………....16

Analytic Approach…………….....................……………………………………….21

Results: Circadian Effects on Encoding…………………...............……………………..23

Effect of Time of Day on Sleep-delay and Wake-delay
Conditions.…………………………………………………………….........................23

Subjective valence and arousal ratings………..........………………………..24

Effect of sleep on memory performance….........…………………………....25

Discussion: Benefits on cued recall and recollection…………………………............……30

Effect of sleep on emotional declarative memory……........……………….31

Effect of sleep on associative declarative memory……….....…………....35

Conclusions………………………….........................…………………………………36

References 37

Appendix 60

About this Master's Thesis

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School	Laney Graduate School
Department	Psychology
Degree	MA
Submission	Master's Thesis
Language	English
Research Field	Psychology, Behavioral Psychology, Experimental Psychology, Cognitive
关键词	Associative memory Episodic memory Declarative memory Emotion Sleep Memory consolidation
Committee Chair / Thesis Advisor	Hamann, Stephan, Emory University
Committee Members	Manns, Joseph, Emory University Bauer, Patricia, Emory University

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