Bottom-Up and Top-Down Mechanisms of General Anesthetics Modulate Different Dimensions of Consciousness
Frontiers in Neural Circuits June 20, 2017 George A. Mashour, Anthony G. Hudetz 136 citations
General anesthetics may suppress consciousness through two complementary neural pathways: a bottom-up mechanism that alters arousal by acting on brainstem and diencephalon sleep-wake nuclei, and a top-down mechanism that disrupts cortical and thalamocortical circuits responsible for integrating information. This article synthesizes these approaches by mapping them to two interrelated dimensions of consciousness—level and content. The framework explains why different anesthetic drugs produce diverse effects on subjective experience. The authors argue that level and content interact to generate consciousness, and understanding this interaction is key to explaining how anesthetics induce unconsciousness.