Quantifying states of consciousness by means of intrinsic brain connectivity

Consciousness is seemingly lost and recovered every day, from the moment we fall asleep until we wake up. Although these departures from wakefulness bring about different changes in brain function, behavior, and neurochemistry, they all lead to lack of reported subjective experience. Here, I will show how ongoing brain activity has been characterized in different states of unconsciousness, such as pharmacologically-induced anesthesia in humans and in noncommunicating states after severe brain injury. By and large, these investigations indicate that during unconscious states cortical long-range correlations are disrupted in both space and time, anticorrelated cortical interactions disappear, and that temporal dynamics are limited to describe specific patterns which are dominated by rigid functional configurations tied to the anatomical connectivity