Non-equilibrium brain dynamics as a signature of consciousness
arXiv Preprint Archive – December 19, 2020
Source: arXiv
Summary
Our brains operate far from equilibrium during consciousness, like a bustling city that never settles down. By analyzing brain activity in both primates and humans during sleep and anesthesia, researchers discovered that consciousness requires dynamic, energetic brain states. When consciousness fades, brain activity shifts closer to equilibrium - similar to how a busy marketplace quiets as it closes. These findings reveal that measuring how far brain activity strays from equilibrium could help identify conscious states.
Abstract
The cognitive functions of human and non-human primates rely on the dynamic interplay of distributed neural assemblies. As such, it seems unlikely that cognition can be supported by macroscopic brain dynamics at the proximity of thermodynamic equilibrium. We confirmed this hypothesis by investigating electrocorticography data from non human primates undergoing different states of unconsciousness (sleep, and anesthesia with propofol, ketamine, and ketamine plus medetomidine), and funcional magnetic resonance imaging data from humans, both during deep sleep and under propofol anesthesia. Systematically, all states of reduced consciousness unfolded at higher proximity to equilibrium dynamics than conscious wakefulness, as demonstrated by entropy production and the curl of probability flux in phase space. Our results establish non-equilibrium macroscopic brain dynamics as a robust signature of consciousness, opening the way for the characterization of cognition and awareness using tools from statistical mechanics.