Associations between sleep and episodic memory updating

Natalie B. Bryant, Lynn Nadel, Rebecca L. Gómez

Research output: Contribution to journalArticle

Abstract

Prior research shows that contextual reminders can reactivate hippocampal links to previously consolidated memories, rendering them susceptible to being updated with new information which then is reconsolidated. Studies implicate sleep in the reconsolidation of reactivated memories, but it is unknown what role sleep plays in updating of a previously consolidated trace with new information. We tracked participants' sleep during an episodic reconsolidation paradigm, first with actigraphy (Experiment 1) then with polysomnography (Experiment 2). Our paradigm involved two learning sessions and a retrieval session, each separated by 48 hr. We reminded participants of the first learning experience immediately prior to the second, which led them to update the earlier memory with elements of the later experience. In Experiment 1, less sleep after Session 1 and more sleep after Session 2 are associated with increased updating. In Experiment 2, N2 sleep spindles (SSs) after the reminder and new learning are associated with more updating, but primarily when spindle activity after Session 1 is low. Thus, total sleep time and N2 SSs contribute to sleep-dependent updating of episodic memory. This outcome is consistent with other work connecting SS activity to the integration of novel information into existing knowledge structures, extended here with the study of how variations in sleep over successive nights contribute to this process. We discuss some possible roles of spindles in the decontextualization of hippocampal memory over time. Although much work addresses the role of sleep in the consolidation of new memories, this work uniquely addresses the contribution of sleep to the updating of a previously consolidated trace with new information.

Original languageEnglish (US)
Pages (from-to)794-805
Number of pages12
JournalHippocampus
Volume30
Issue number8
DOIs
StatePublished - Aug 1 2020

Keywords

  • episodic memory
  • hippocampus
  • integration
  • memory consolidation
  • reconsolidation
  • spindles

ASJC Scopus subject areas

  • Cognitive Neuroscience

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