A week in the life of the human brain: stable states punctuated by chaotic transitions

Many important neurocognitive states, such as ones related to performing natural activities and fluctuations of arousal, shift over minutes-to-days in the real-world. We analyzed 3–12 days of continuous intracranial recordings in twenty participants that freely socialized, used digital devices, slept, etc. to understand how neural dynamics form and change with behavior. Brain networks formed stable states that were predictive of both behavior and physiology. Behavior changes were associated with bursts of rapid neural fluctuations where brain networks chaotically explored many configurations before settling into new states. These trajectories traversed an hourglass-like structure, with awake and sleep at opposite ends, and an attractor state represented by default mode network activation in between. These findings illustrate ways our brains balance stability and flexibility to produce real-world behavior.