How ripples in our brains synchronize memories during sleep

According to a study, brain recordings show that ripples are ubiquitous and occur simultaneously in widely distributed brain regions during human sleep, waking, and memory recall. The results showed that 90-Hertz ripples, which lasted approximately 70 milliseconds, occurred simultaneously and had consistent phase lags across multiple distant cortical areas during sleep and waking. Here, using recordings inside the human brain, we show that ripples occur simultaneously in multiple lobes in both cortical hemispheres and the hippocampus, generally during sleep and waking, and especially during memory recall. Here, using intracranial recordings in humans, we report that these 70-ms-duration, 90-Hz ripples often couple, co-occur, and, crucially, phase-lock between widely distributed focal cortical locations during both sleep and waking, even between hemispheres.