Nonequilibrium brain dynamics as a signature of consciousness

Area of Science:

• Neuroscience
• Statistical Mechanics
• Cognitive Science

Background:

• Cognitive functions in primates depend on complex neural interactions.
• Macroscopic brain dynamics near equilibrium are unlikely to support cognition.

Purpose of the Study:

• To investigate the relationship between brain dynamics and consciousness.
• To determine if non-equilibrium dynamics are essential for conscious states.

Main Methods:

• Analysis of electrocorticography (ECoG) data from nonhuman primates during various states of unconsciousness (sleep, propofol, ketamine, ketamine plus medetomidine).
• Analysis of functional magnetic resonance imaging (fMRI) data from humans during deep sleep and propofol anesthesia.
• Computation of entropy production and curl of probability flux in phase space to assess proximity to equilibrium.

Main Results:

• All states of reduced consciousness (sleep, anesthesia) showed higher proximity to equilibrium compared to conscious wakefulness.
• Non-equilibrium macroscopic brain dynamics were consistently observed during conscious states.

Conclusions:

• Non-equilibrium macroscopic brain dynamics are a robust signature of consciousness.
• These findings suggest statistical mechanics tools can characterize cognition and awareness.