Consciousness is one of the great philosophical mysteries that continues to befuddle modern inquiry. As scientists grapple with this mystery there are some intriguing clues from the application of anesthesia. From New Scientist:
But is it even realistic to expect to find a discrete site or sites acting as the mind’s “light switch”? Not according to a leading theory of consciousness that has gained ground in the past decade, which states that consciousness is a more widely distributed phenomenon. In this “global workspace” theory, incoming sensory information is first processed locally in separate brain regions without us being aware of it. We only become conscious of the experience if these signals are broadcast to a network of neurons spread through the brain, which then start firing in synchrony.
The idea has recently gained support from recordings of the brain’s electrical activity using electroencephalograph (EEG) sensors on the scalp, as people are given anaesthesia. This has shown that as consciousness fades there is a loss of synchrony between different areas of the cortex – the outermost layer of the brain important in attention, awareness, thought and memory.