Consciousness, Anesthesia, and Acetylcholine
Anesthesiology February 26, 2021 D. Pal, G. Mashour
Cortical acetylcholine concentration tracks with the capacity for conscious experience: high during wakefulness, low during slow-wave sleep, and high again during REM sleep when dreaming occurs. General anesthetics produce parallel changes—GABAergic drugs like propofol and sevoflurane lower acetylcholine and reduce the probability of experience, while non-GABAergic drugs like ketamine and nitrous oxide raise acetylcholine and increase the likelihood of dreams or hallucinations. Interventions that raise brain acetylcholine reverse anesthetic traits or reduce potency in humans and rodents, whereas lesions of cholinergic neurons in the basal forebrain reduce anesthetic requirements for isoflurane and propofol.