How the brain transitions from conscious to subliminal perception

We study the transition in the functional network that characterize the human brains' conscious state to an unconscious subliminal state of perception by using k-core percolation. We find that the most inner core (ie, the most connected kernel) of the functional network in the state of consciousness (the visual cortex and the left middle frontal gyrus) is represented by the areas that remain active when the brain transitions to the subliminal unconscious state. That is, the inner core of the conscious network coincides with the unconscious state. Based on data analysis and mathematical modeling we interpret these results as a transition driven by k-core percolation, where the conscious state is inactivated by the disappearance of the peripheral shells in the k-shell decomposition structure. Thus, the inner core and most robust component of the brain seems to be the unconscious subliminal state. If this result were to be found valid for other states of the brain, it could set interesting constraints to models of consciousness and brain structure, in that the location of the core of the functional brain network is in the unconscious part of the brain rather than in the conscious state as previously thought.