Thalamic activity is a neural correlate of connected consciousness

Dissociating the neural mechanisms responsible for the altered states of consciousness during anaesthesia from the non-specified drug-related effects remains a challenge in consciousness research.1 We used anaesthesia to investigate differences in functional brain activity during the presence and absence of connected consciousness (PoCC and AoCC, respectively) by administering various anaesthetics at concentrations designed to render 50% of the subjects unresponsive.