Sharp wave-ripples in human amygdala and their coordination with hippocampus during NREM sleep

Abstract

Cooperative interactions between the amygdala and hippocampus are widely regarded as critical for overnight emotional processing of waking experiences, but direct support from the human brain for such a dialog is absent. Using intracranial recordings in four pre-surgical epilepsy patients (two male, two female), we discovered ripples within human amygdala during non-rapid eye movement (NREM) sleep. Like hippocampal ripples, amygdala ripples are strongly associated with sharp waves, are linked to sleep spindles, and tend to co-occur with their hippocampal counterparts. Moreover, sharp waves and ripples are temporally linked across the two brain structures, with amygdala ripples occurring during hippocampal sharp waves and vice versa. Combined with further evidence of interregional sharp wave and spindle synchronization, these findings offer a potential physiological substrate for the NREM-sleep-dependent consolidation and regulation of emotional experiences.