Brain Activity and Changes in Consciousness During General Anesthesia

This study aims to investigate how general anesthetics alter brain activity and consciousness across different age groups. The study will evaluate four anesthetic agents with different mechanisms of action: propofol, remimazolam, esketamine, and dexmedetomidine. Electroencephalography (EEG) will be recorded during wakefulness, anesthetic induction, loss of responsiveness, and recovery of responsiveness to characterize changes in brain activity and brain network dynamics. The study includes children aged 6-12 years undergoing surgery, healthy young adults aged 20-40 years, and healthy older adults aged 65-80 years. Resting-state EEG will be used to examine changes in brain rhythms, temporal and spatial brain dynamics, and network organization across different levels of consciousness. In a subgroup of young adult participants, auditory stimuli will also be presented continuously to investigate how the brain processes sounds and meaningful information as consciousness decreases and subsequently recovers. The study will compare EEG changes across anesthetic agents, age groups, and states of consciousness. It will also evaluate the timing of loss and recovery of responsiveness, anesthetic dose-response relationships, and adverse events. The overall goal is to identify brain activity patterns associated with anesthesia-induced changes in consciousness and to provide a scientific basis for improved monitoring of consciousness and anesthetic depth.