Cortical ripples provide the conditions for consolidation during NREM sleep in humans

Hippocampal ripples index the reconstruction of spatiotemporal neuronal firing patterns essential for the consolidation of memories in the cortex during non-rapid eye movement (NREM) sleep. However, it is not known whether ripples are generated in the human cortex during sleep. Here, using human intracranial recordings, we show that ~70ms long ~80Hz ripples are ubiquitous in all regions of the cortex during NREM sleep as well as waking. During waking, cortical ripples occur on local high frequency activity peaks. During sleep, cortical ripples occur during spindles on the down-to-upstate transition, with unit-firing patterns consistent with generation by pyramidal-interneuron feedback. Cortical ripples mark the recurrence of spatiotemporal activity patterns from preceding waking, and they group co-firing within the window of spike-timing-dependent plasticity. Thus, cortical ripples guided by sequential sleep waves may facilitate memory consolidation during NREM sleep in humans.