Awake Reactivation of Prior Experiences Consolidates Memories and Biases Cognition

• Published in: Trends in cognitive sciences 2019-10, Vol.23 (10), p.876-890
• Main Authors: Tambini, Arielle, Davachi, Lila
• Format: Article
• Language: English
• Subjects: awake rest; hippocampal interactions; hippocampus; memory consolidation; reactivation; replay
• ISSN: 1364-6613; 1879-307X
• DOI: 10.1016/j.tics.2019.07.008

After experiences are encoded into memory, post-encoding reactivation mechanisms have been proposed to mediate long-term memory stabilization and transformation. Spontaneous reactivation of hippocampal representations, together with hippocampal–cortical interactions, are leading candidate mechanisms for promoting systems-level memory strengthening and reorganization. While the replay of spatial representations has been extensively studied in rodents, here we review recent fMRI work that provides evidence for spontaneous reactivation of nonspatial, episodic event representations in the human hippocampus and cortex, as well as for experience-dependent alterations in systems-level hippocampal connectivity. We focus on reactivation during awake post-encoding periods, relationships between reactivation and subsequent behavior, how reactivation is modulated by factors that influence consolidation, and the implications of persistent reactivation for biasing ongoing perception and cognition. Recent human fMRI studies provide evidence for spontaneous memory-related reactivation and hippocampal interactions during awake post-encoding time periods.Post-encoding awake reactivation is modulated by factors that influence memory consolidation, such as salience and reward, and predicts behavioral memory integration and the reorganization of cortical memory representations.Reactivation of prior brain states may bias the way in which new information is experienced, perceived, and acted upon.Several open questions remain, such as how awake reactivation is related to ongoing conscious experience, which awake brain states may be optimal for supporting reactivation and memory retention, and how reactivation during sleep and wake may interact to ultimately support memory consolidation and retention.