An acetylcholine-inhibited sleep-active hippocampal interneuron orchestrates memory consolidation.

Chrm2-expressing hippocampal interneurons inhibit hippocampal ripples during NREM sleep and are essential for spatial and social memory consolidation in mice.

• Why it matters: Understanding how sleep-dependent memory consolidation occurs at the circuit level remains incomplete, especially regarding the molecular mechanisms that regulate ripple generation critical for this process.
• What they did: The study identified a specific population of Chrm2-expressing GABAergic interneurons active during NREM sleep, which inhibit the hippocampus in infra-slow rhythms and modulate ripple occurrence through widespread inhibition, with activity suppression impairing memory.
• The result: These findings suggest that Chrm2+ interneurons link neuromodulatory states to memory consolidation, providing targets for interventions in cognitive disorders related to sleep and memory.