Sleep mediates retention and post-retrieval processing of source memory

• Published in: Neuropsychologia Vol. 49; no. 9; pp. 2619 - 2629
• Main Authors: Lewis, P.A., Manning, L.M., Critchley, H.D.
• Format: Journal Article
• Language: English
• Published: 19.05.2011
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2011.05.009

Sleep plays a role in the consolidation of declarative memories, and has been shown to influence emotional representations more strongly than neutral ones. Although these effects have attracted much attention, few studies have examined their neural correlates. Here, we studied the impact of sleep upon source memory at both behavioural and neural levels. Emotional and neutral sources were retrieved following a twelve hour retention interval including either wake only or wake plus sleep. Our data show reduced forgetting and increased responses in hippocampus and superior parietal cortex during source memory after sleep. Additionally, we reveal a task-specific interaction between sleep and emotional valence, with left amygdala and components of the episodic memory system including right parahippocampus and posterior cingulate more active during emotional memory after sleep. Because these brain responses were not associated with superior memory, and because they were only observed when emotion was specifically relevant to the retrieval task, we interpret them as markers of altered post-retrieval processing. Overall, our findings extend prior work by demonstrating that sleep exerts a protective influence upon source memory, and that this is mediated by enhanced responses in hippocampus and superior parietal cortex. Additionally, we provide novel evidence that sleep can impact upon the manipulation of freshly recalled information when it is relevant to the task at hand.