Widespread ripples synchronize human cortical activity

Hippocampal ripples index the reconstruction of spatiotemporal neuronal firing patterns essential for the consolidation of memories in cortex during sleep. Here, using human intracranial recordings, we show that ripples are also ubiquitous in the cortex during both waking and non-rapid eye movement sleep. During sleep, cortical ripples are generated on the down-to-upstate transition with phase-locked firing patterns indicating generation by pyramidal-interneuron feedback. They mark recurrence of spatiotemporal patterns from preceding waking, and group co-firing to facilitate plasticity. During waking, cortical ripples co-occur with hippocampal ripples during local activity peaks, and co-occur preceding memory recall. During sleep and waking, cortical ripples co-occur and phase-synchronize across widespread locations, including between hemispheres, providing a possible substrate for event-integration during memory and more generally in cognition.