Loss of cortical integration and changes in the dynamics of electrophysiological brain signals characterize the transition from wakefulness towards unconsciousness. In this study, we arrive at a basic model explaining these observations based on the theory of phase transitions in complex systems. We studied the link between spatial and temporal correlations of large-scale brain activity recorded with functional magnetic resonance imaging during wakefulness, propofol-induced sedation and loss of consciousness and during the subsequent recovery. We observed that during unconsciousness activity in frontothalamic regions exhibited a reduction of long-range temporal correlations and a departure of functional connectivity from anatomical constraints. A model of a system exhibiting a phase transition reproduced our findings, as well as the diminished sensitivity of the cortex to external perturbations during unconsciousness. This framework unifies different observations about brain activity during unconsciousness and predicts that the principles we identified are universal and independent from its causes.
Friday, February 05, 2016
Consciousness as the product of carefully balanced chaos.
Tagliafuochi and collaborators have provided more evidence that our experience of consciousness and reality might result from a delicate balance or critical level of connectivity between brain networks in which the brain explores the maximum number of unique pathways to generate meaning. Consciousness slips away if there is too much or too little connectivity. Their abstract: