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bioRxiv · 10.64898/2026.09.02.748785

Hippocampal CA1 neurons are crucial for sleep-associated memory formation in humans: The role of theta power during NREM sleep

Hanert, A.·Kurz, E.-M.·Weber, F. D.·Doehring, J.·Pedersen, A.·Burgalossi, A.·Born, J.·Bartsch, T.
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Abstract

The formation of long-term memory during sleep depends on the reactivation and redistribution of recently acquired mnemonic information during non-rapid eye movement (NREM) sleep. Animal studies suggest that hippocampal memory replay during slow-wave sleep is coordinated through the interaction of sharp-wave ripples, thalamocortical sleep spindles, and neocortical slow oscillations (SOs). However, direct evidence for the contribution of hippocampal network dynamics to sleep-dependent memory consolidation in humans remains limited. Here, we investigated sleep-dependent memory consolidation in patients (n=13) with transient global amnesia (TGA), a clinical syndrome associated with focal and transient lesions of the hippocampal CA1 region. Patients completed a verbal paired-associative learning task followed by nocturnal polysomnography and subsequent memory retrieval during the acute phase of TGA (acute condition) and again after clinical recovery (follow-up condition). Overnight memory consolidation was significantly impaired during the acute phase compared with the follow-up session. NREM EEG theta power (4-8 Hz) was reduced during the acute phase of TGA. Importantly, increases in theta power from the acute to the follow-up session predicted corresponding improvements in memory consolidation within individuals. In contrast, established NREM markers of sleep-dependent memory consolidation, including sleep spindle density, SO density, and SO-spindle coupling, did not differ between the acute and follow-up conditions. These findings suggest that transient hippocampal CA1 dysfunction disrupts sleep-related hippocampal network dynamics reflected in reduced NREM theta activity, which in turn is associated with impaired memory consolidation. Sleep-related theta oscillations may therefore represent a functional marker of hippocampal network integrity during sleep-dependent memory consolidation in humans.

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Hanert, A., Kurz, E.-M., Weber, F. D., Doehring, J., Pedersen, A., Burgalossi, A., Born, J., Bartsch, T.. 2026-09-08. Hippocampal CA1 neurons are crucial for sleep-associated memory formation in humans: The role of theta power during NREM sleep. https://doi.org/10.64898/2026.09.02.748785

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