Consciousness re-emerges from propofol-induced general anesthesia through a multiscale reorganization of brain activity, not a single event. Anesthesia is an organized low-frequency regime with aperiodic slow waves, alpha/beta rhythms, global alpha synchronization, and phase-amplitude coupling. After anesthetic cessation, this regime dissolves as neural excitability and complexity increase. Conscious behavior returns with a rapid transformation in high-gamma activity, shifting from random bursts to structured, task-selective, event-locked responses. The findings chart an electrophysiological map of how conscious cognition is extinguished, reconfigured, and restored in the human brain.
Conscious awareness is needed for integrating basic sensory features into coherent percepts. Using intracranial recordings in awake and anesthetized states, the study found that in the awake state, the brain automatically encodes individual auditory features (loudness and tone) and binds them together without attention, within a localized sensory cortical network. In the anesthetized state, encoding of single attributes is preserved, but binding is abolished, and anesthesia mainly affects later cortical processes after stimulus offset. These results suggest the functional boundary of consciousness lies between encoding and manipulation of basic sensory features at local cortical circuits, rather than global computations.