0111 Emotional Memory-Associated Voxel-Extent Reactivation During Episodic Memory Retrieval Varies as a Function of Post-Learning Sleep

Abstract

Abstract Introduction Slow wave sleep (SWS) and rapid eye-movement (REM) sleep enhance neutral and emotional memory consolidation, respectively. Emotional episodic memory retrieval is also enhanced when encoding-specific functional brain patterns are reactivated at retrieval, especially in ventral visual stream and frontal brain regions as well as amygdala. Here we investigate how sleep impacts the association between memory-dependent brain pattern reactivation and episodic memory retrieval. Methods Healthy adults (N = 22; 11F, 11M; age: 19–29 years) were scanned during an incidental encoding task and a surprise recognition memory task 24h later. Overnight sleep was monitored with polysomnography. During encoding, participants viewed line drawings of negative, neutral, and positive images, each followed by their full-colored photo. At recognition, participants distinguished new from encoded line drawings. Brain reactivation was measured at the single-subject level as the percentage of voxels activated at encoding that were also activated during successful recognition (reactivation%); this metric was calculated independently in whole-brain and 3 ROI-based maps (inferior temporal lobe (ITL), medial prefrontal cortex, and amygdala). Multiple linear regression was performed to predict memory performance from functional brain reactivation and sleep physiology. Results In whole-brain analyses, the association between negative memory performance and reactivation% decreased with greater REM sleep amount. This interaction approached significance for positive, but was not significant for neutral, memory performance. Additionally, the association between neutral, but not emotional, memory performance and reactivation% decreased with greater amounts of SWS sleep. In ROI-based analyses, positive, but not negative or neutral, memory performance was independently predicted by REM sleep amount and ITL reactivation%. No effects of SWS amount were observed in ROI-based analyses. Conclusion Greater amounts of sleep decreased the association between brain reactivation and memory performance. Sufficient sleep may change cortical representations of episodic memories, resulting in less reliance on encoding-related reactivation during memory retrieval. Support NSF Grant BCS 1539361