Signatures of awareness in the dynamics of resting-state brain activity.
At rest, the brain is traversed by spontaneous functional connectivity patterns. Two hypotheses have been proposed for their origins: they may reflect a continuous stream of ongoing cognitive processes as well as random fluctuations shaped by a fixed anatomical connectivity matrix. In this presentation, I’ll show that both sources contribute to the shaping of resting-state networks, yet with distinct contributions during consciousness and anesthesia. I’ll present two studies, using functional connectivity and fMRI, where we contrasted conscious versus conscious conditions (anesthesia in the first case and brain-injuries in the second). In both cases, un-conscious conditions where characterized by a frequent functional connectivity patterns that inherits the structure of anatomical connectivity, exhibits fewer small-world properties, and lacks negative correlations. Conversely, also in both studies, wakefulness is characterized by the sequential exploration of a richer repertoire of functional configurations, often dissimilar to anatomical structure, and comprising positive and negative correlations among brain regions. These results reconcile theories of consciousness with observations of long-range correlation in the anesthetized brain and show that a rich functional dynamics might constitute a signature of consciousness, with potential clinical implications for the detection of awareness in anesthesia and brain-lesioned patients.