Schedule of Events | Symposia

Coupled sleep rhythms in the human hippocampus support memory consolidation

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom
Also presenting in Data Blitz Session 1 - Saturday, March 29, 2025, 10:30 am – 12:00 pm EDT, Grand Ballroom.

Manqi Sha¹ (manqi.sha@psy.ox.ac.uk), Pin-Chun Chen¹, Yvonne Y. Chen², Kathryn A. Davis², H. Isaac Chen², Brett.L Foster², Bernhard P. Staresina¹; ¹University of Oxford, ²University of Pennsylvania

Sleep plays an active role in memory consolidation. This process is thought to be facilitated by characteristic neural oscillations during non-rapid eye movement (NREM) sleep, including slow oscillations (SOs, <1 Hz), spindles (12–16 Hz), and ripples (80–120 Hz). Previous invasive recordings from the human hippocampus have shown that rather than operating independently, these oscillations are temporally coordinated. However, whether coupled sleep rhythms in the hippocampus contribute to memory consolidation has remained unknown. To address this question, we analysed intracranial EEG (iEEG) recordings from the hippocampus of 12 participants undergoing invasive monitoring for epilepsy surgery. Each participant underwent one or two sessions, consisting of overnight sleep and pre- and post-sleep memory tasks. In each session, participants learned 100 verb-image pairs, with immediate recall before sleep testing 50% of the pairs and delayed recall after sleep testing the remaining pairs. Behavioural results confirmed that longer NREM sleep is associated with better memory retention. Consistent with prior research, we observed specific temporal dynamics of hippocampal sleep rhythms: spindles were preferentially nested within SO up-states, and ripples aligned with the waxing phase of spindles. Crucially, the precision of SO-spindle coupling in the hippocampus predicted overnight memory retention, with stronger spindle coupling to the SO up-states linked to improved memory performance. These findings highlight the intricate role of coupled hippocampal oscillations in supporting memory consolidation, offering insights into the neural mechanisms underlying sleep-dependent memory processes.

Topic Area: LONG-TERM MEMORY: Episodic