One area in which we have made great progress is in discovering the physical or neural correlates of consciousness – what consciousness in the brain "looks like", you might say. One way to investigate this question is to see what changes when consciousness is reduced or absent, as happens when people are in a vegetative state, with no sign of awareness.
Brain scans show that such people usually have damage to the thalamus, a relay centre located smack-bang in the middle of the brain. Another common finding is damage to the connections between the thalamus and the prefrontal cortex, a region at the front of the brain, generally responsible for high-level complex thought.
Via Complexity Digest