We show that neurons tuned to later remembered memories are preferentially reactivated during sleep ripples, linking the replay of individual neurons to successful memory consolidation.

Sleep ripples drive single-neuron reactivation for human memory consolidation
https://www.biorxiv.org/content/10.64898/2026.03.27.714528v1.abstract

Rodent studies identified hippocampal ripples as a core mechanism of memory consolidation and neuronal replay, and human imaging revealed macroscopic patterns of offline reactivation. But the cellular basis of human memory consolidation remains unknown.

Using rare intracranial recordings, we simultaneously measured single-neuron activity and intracranial EEG during wakefulness and sleep, allowing us to identify ripples and ripple-locked neuronal firing in the human brain.

We found that human ripples robustly drive neuronal firing, with sleep ripples eliciting stronger activation than wake ripples.

How is this reactivation linked to behaviour? We constructed a memory task around neurons that responded to specific stimuli used during learning. This allowed us to compare ripple-triggered reactivation across neurons responding to remembered versus forgotten stimuli.

We discovered that neurons tuned to items that were later remembered fired more strongly during ripples than neurons coding for forgotten items. This memory-linked reactivation was selectively observed during sleep.