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The context in which learning occurs is sufficient to reconsolidate stored memories and neuronal reactivation may be crucial to memory consolidation during sleep. The mechanisms of context-dependent and sleep-dependent memory (re)consolidation are unknown but involve the hippocampus. We simulated memory (re)consolidation using a connectionist model of the hippocampus that explicitly accounted for its dorsoventral organization and for CA1 proximodistal processing. Replicating human and rodent (re)consolidation studies yielded the following results. (1) Semantic overlap between memory items and extraneous learning was necessary to explain experimental data and depended crucially on the recurrent networks of dorsal but not ventral CA3. (2) Stimulus-free, sleep-induced internal reactivations of memory patterns produced heterogeneous recruitment of memory items and protected memories from subsequent interference. These simulations further suggested that the decrease in memory resilience when subjects were not allowed to sleep following learning was primarily due to extraneous learning. (3) Partial exposure to the learning context during simulated sleep (i.e., targeted memory reactivation) uniformly increased memory item reactivation and enhanced subsequent recall. Altogether, these results show that the dorsoventral and proximodistal organization of the hippocampus may be important components of the neural mechanisms for context-based and sleep-based memory (re)consolidations.
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This content will become publicly available on February 1, 2027
The default mode network: where spontaneous thought meets memory consolidation
The default mode network (DMN) is a distributed set of brain regions engaged during wakeful rest. Spontaneous thoughts — internally directed mental experiences that arise with relative freedom and few constraints on their content or transitions — are ubiquitous during wakeful rest. Spontaneous memory reactivation — neural events in which recently learned information is reinstated — also occurs at rest and has a fundamental role in long-term memory consolidation. Here, we synthesize emerging behavioral, theoretical, and neurophysiological evidence suggesting that DMN activity associated with spontaneous thought provides a neural context that promotes the propagation of reactivated information to aid consolidation. We highlight )ndings linking spontaneous thought to improved memory performance, discuss how speci)c DMN subsystems coordinate with the hippocampus during reactivation, and highlight recent studies that connect spontaneous thought content to memory reactivations. We conclude by outlining future directions to clarify the mechanistic role of spontaneous thought in memory consolidation mediated by the complex interplay between the DMN, hippocampus, and broader cortical networks.
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- Award ID(s):
- 2528643
- PAR ID:
- 10657547
- Publisher / Repository:
- Science Direct
- Date Published:
- Journal Name:
- Current Opinion in Behavioral Sciences
- Volume:
- 67
- Issue:
- C
- ISSN:
- 2352-1546
- Page Range / eLocation ID:
- 101622
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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