Differential Cortical Network Engagement During States of Un/Consciousness in Humans

Abstract What happens in the human brain when we are unconscious? Despite substantial work, we are still unsure which brain regions are involved and how they are impacted when consciousness is disrupted. Using intracranial recordings and direct electrical stimulation, we mapped global, network, and regional involvement during wake vs. arousable unconsciousness (sleep) vs. non-arousable unconsciousness (propofol-induced general anesthesia). Information integration and complex processing were reduced, while variability increased in any type of unconscious state. These changes were more pronounced during anesthesia than sleep. They also involved different cortical engagement; During sleep, changes were mostly uniformly distributed across the brain while during anesthesia the prefrontal cortex was the most disrupted, suggesting that the obliteration of consciousness during anesthesia results not from just altered overall physiology but from a disconnection between prefrontal and other brain areas. These findings provide direct evidence of the different neural signatures for different types of unconsciousness.