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. 2026 Jan 21;114(2):226-236.e6.
doi: 10.1016/j.neuron.2025.10.003. Epub 2025 Nov 7.

Large sharp-wave ripples promote hippocampo-cortical memory reactivation and consolidation during sleep

Heath Larsson Robinson  1 , Ralitsa Todorova  1 , Gergo Attila Nagy  2 , Anna Gruzdeva  1 , Praveen Paudel  1 , Azahara Oliva  1 , Antonio Fernandez-Ruiz  3
Affiliations

Large sharp-wave ripples promote hippocampo-cortical memory reactivation and consolidation during sleep

Heath Larsson Robinson et al. Neuron. .

Abstract

During sleep, ensemble activity patterns encoding recent experiences are reactivated in the hippocampus and cortex. This reactivation is coordinated by hippocampal sharp-wave ripples (SWRs) and is believed to support the early stages of memory consolidation. However, only a minority of sleep SWRs are associated with memory reactivation in the hippocampus and its downstream areas. Whether that subset of SWRs has specific physiological characteristics and directly contributes to memory performance is not known. We identified a specific subset of large SWRs linked to memory reactivation in both the hippocampus and prefrontal cortex (PFC) of mice, and found that their occurrence selectively increased during sleep following new learning. Closed-loop optogenetic SWR boosting during sleep was sufficient to enhance ensemble memory reactivation in the hippocampus and PFC. This manipulation also improved subsequent memory retrieval and hippocampal-PFC coordination during waking, causally linking both phenomena to SWR-associated ensemble reactivation during sleep.

Keywords: cell assemblies; hippocampus; learning; memory; network dynamics; oscillations; reactivation; replay; sharp-wave ripples; synchrony.

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Conflict of interest statement

Declaration of interests The authors declare no competing interests.

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