A new study from the MIT Picower Institute shows how consciousness breaks down under general anesthesia. Conscious thought requires synchronized communication which is mediated by brain rhythms in specific frequency bands between basic sensory and higher-order cognitive regions of the brain. Cognition-oriented brain regions use relatively low-frequency alpha and beta rhythms to suppress the processing by sensory regions of stimuli that have become familiar and mundane in the environment.
When sensory regions detect a surprise, they use faster frequency gamma rhythms to tell the higher regions about it, and the higher regions process the gamma frequencies to decide what to do. Results from the Proceedings of the National Academy of Sciences show that animals under anesthesia had a sensory region that retained the capacity to detect simple surprises, but communication with a higher cognitive region toward the front of the brain was lost.
These new results contribute to the scientific interest in the mechanisms of consciousness and how it relates to the ability of the brain to perform predictions. Additionally, the results suggest that the prefrontal areas of the brain help spark the “ignition event” and allow sensory information to become conscious. This new information will help scientists narrow down possible models for mechanisms of consciousness.
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