The Riddle of Consciousness

The assorted mystics, philosophers, theologians and, most recently, neuroscientists who have burned a candle searching for the essence of consciousness all started with a simple presumption: Consciousness must begin where unconsciousness ends.

Theologians have likened this state of pre-awakening to sleep, to darkness, to life underground. Modern scientists study the neural processes of sleep itself, and the transition to waking; they also have analyzed what happens in the brain when people suddenly become consciously aware of an object that was hidden in plain sight.

So far, the precise neural correlates of consciousness — the brain circuits critical to “turning on” conscious awareness — have eluded capture.

One reason is that consciousness itself takes many forms, from the gauzy half-dream state between the alarm clock’s bleating and sitting up; and lost stretches of waking life, as when a driver pulls into the driveway with no recollection of the half-hour commute home.

The deeper that investigators dig, the more hidden chambers they find. Last Wednesday, scientists in England and Belgium reported that five people with severe brain injuries who had been identified as “vegetative,” beyond reach, showed activity on brain imaging that strongly suggested conscious awareness. One of them, a 29-year-old man thought to be “vegetative” for five years, began to answer yes and no questions by alternately showing brain activity when thinking about tennis (lighting motor areas), then about walking in his house (lighting spatial areas).  Read Article

By Benedict Carey