Physical review. E
July 28, 2021
Yonatan Sanz Perl, Hernan Bocaccio, Carla Pallavicini et al.
82 citations
Conscious wakefulness is characterized by brain dynamics far from thermodynamic equilibrium, while states of reduced consciousness—such as deep sleep and anesthesia induced by propofol, ketamine, or ketamine plus medetomidine—operate closer to equilibrium. This conclusion comes from analyzing electrocorticography data from nonhuman primates and functional magnetic resonance imaging data from humans. Entropy production and the curl of probability flux in phase space reliably distinguished conscious from unconscious states. The findings establish nonequilibrium macroscopic brain dynamics as a robust signature of consciousness and offer a statistical mechanics framework for studying cognition and awareness.
bioRxiv Preprint Server
September 2, 2021
Laura De la Fuente, Federico Zamberlán, Hernan Bocaccio et al.
preprint
The laws of physics are time-symmetric, but dissipative systems like the brain show a preferred temporal direction. Using a deep learning framework inspired by stochastic thermodynamics, researchers analyzed electrocorticography signals from non-human primates. Brain activity during conscious wakefulness could be distinguished from its time-reversed version with high accuracy, using both frequency and phase information. This ability was reduced during deep sleep and ketamine-induced anesthesia. Transitions between slow (≈20 Hz) and fast frequencies (> 40 Hz) mainly contributed to the temporal asymmetry seen during wakefulness. The findings suggest that a preferred temporal direction in neural activity correlates with conscious awareness, linking brain processes to the subjective experience of time's passage.
arXiv Preprint Archive
December 19, 2020
Yonatan Sanz Perl, Hernan Bocaccio, Ignacio Perez-Ipina et al.
Consciousness depends on brain activity that is far from thermodynamic equilibrium. Analyzing electrocorticography data from non-human primates during sleep and various anesthetics, and fMRI data from humans during deep sleep and propofol anesthesia, all states of reduced consciousness showed dynamics closer to equilibrium than conscious wakefulness. This was measured by entropy production and the curl of probability flux in phase space. Non-equilibrium macroscopic brain dynamics therefore serve as a robust signature of consciousness, offering a statistical mechanics approach to studying cognition and awareness.