Living systems must constantly work against equilibrium to survive, a property that can be measured through temporal asymmetry in brain signals. Using statistical physics, researchers analyzed reversibility in functional magnetic resonance imaging data from patients with disorders of consciousness. They found that decreased asymmetry and reduced non-stationarity in brain signals characterize impaired consciousness states, consistent with previous findings in sleep and anesthesia. The work aims to identify biomarkers for patient improvement and classification, and to deepen mechanistic understanding of consciousness disorders.
Consciousness has a structure with foreground contents and a background environment, a relation that depends on the brain's interaction with the body and external world. The temporo-spatial theory proposes that the brain aligns its neuronal activity to environmental stimuli across three layers: a background layer with longer timescales creating shared brain similarities across subjects, an intermediate layer with medium timescales matching environmental inputs to intrinsic neuronal rhythms, and a foreground layer with shorter timescales entraining to stimulus timing. These layers correspond to phenomenal layers: a shared contextual background, a layer mediating content relationships, and fast-changing specific contents. This alignment may bridge physical, dynamic, neuronal, and phenomenal mechanisms of consciousness.