The reach of reactivation: Effects of consciously triggered versus unconsciously triggered reactivation of associative memory

• 成果类型: Article
• 署名作者: Tal, Amir; Schechtman, Eitan; Caughran, Bruce; Paller, Ken A.; Davachi, Lila
• 署名单位: Columbia University; University of California System; University of California Irvine; University of California System; University of California Irvine; Northwestern University; Nathan Kline Institute for Psychiatric Research
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14707
• DOI: 10.1073/pnas.2313604121
• 发表日期: 2024-02-26
• 关键词: sleep; consolidation; mechanisms; benefits; promotes; reveal; brain; rest

摘要

Consolidating memories for long - term storage depends on reactivation. Reactivation occurs both consciously, during wakefulness, and unconsciously, during wakefulness and sleep. While considerable work has examined conscious awake and unconscious sleep reactivation, in this study, we directly compare the consequences of conscious and unconscious reactivation during wakefulness. Forty - one participants learned associations consisting of adjective-object-position triads. Objects were clustered into distinct semantic groups (e.g., fruits, vehicles) such that we could examine consequences of reactivation on semantically related memories. After an intensive learning protocol, we systematically reactivated some of the triads by presenting the adjective as a cue. Reactivation was done so that it was consciously experienced for some triads, and only unconsciously processed for others. Memory for spatial positions, the most distal part of the association, was affected by reactivation in a consciousness- dependent and memory- strength- dependent manner. Conscious reactivation resulted in weakening of semantically related memories that were strong initially, resonating with prior findings of retrieval- induced forgetting. Unconscious reactivation, on the other hand, selectively benefited weak reactivated memories, as previously shown for reactivation during sleep. Semantically linked memories were not impaired, but rather were integrated with the reactivated memory. These results taken together demonstrate that conscious and unconscious reactivation have qualitatively different consequences. Results support a consciousness- dependent inhibition account, whereby unconscious reactivation entails less inhibition than conscious reactivation, thus allowing more liberal spread of activation. Findings set the stage for additional exploration into the role of conscious experience in memory storage and structuring. Significance The transformation of memories into long - term storage relies on their reactivation, which typically occurs during sleep or idle wake. Here, we test a hypothesis that this transformation is optimal when reactivation is not consciously experienced, thereby explaining why offline states are better suited for reactivation. Our experiment showed that consciously reactivating a memory benefitted target memories and weakened other associations, whereas unconscious reactivation led to broader non- selective benefits both for the target memory and for memories associated with it. Results provide insight into the mechanisms underlying memory consolidation, supporting the hypothesis that associative spread is greater for unconscious as compared to conscious reactivation.