Mystery Of Consciousness

Suddenly the man stopped, in midsentence, and his face lost animation; his mouth froze, still open, and his eyes became vacuously fixed. For a few seconds he remained motionless. I spoke his name, but there was no reply. Then he began to move a little, he smacked his lips, his eyes shifted to the table between us, he seemed to see a cup of coffee and a small metal vase of flowers; he must have because he picked up the cup and drank from it. I spoke to him again, and again he did not reply."

This incident occurred more than three decades ago, when Dr. Antonio Damasio was a medical student in Lisbon, Portugal, and he has never forgotten it. How was it possible, he wondered, for someone to be there and yet not be there, to be awake and yet not be awake, to be aware of his surroundings and at the same time be oblivious to them? The more Damasio puzzled over what had happened to the patient during an epileptic seizure, the more he felt compelled to confront a much larger question: What is it about the human brain and its networks of neurons that give rise to consciousness?

In recent years scores of scientists have grappled with that profound question, among them mathematical physicist Roger Penrose, biologist Francis Crick and psychiatrist Allan Hobson, as well as many philosophers. Their answers have ranged from the optimism of Tufts University's Daniel Dennett, who says consciousness will one day be understood as nothing more complicated than a kind of biological software routine, to the outright pessimism of Rutgers University's Colin McGinn. He regards consciousness as "the ultimate mystery, a mystery that human intelligence will never unravel."

Now it's Damasio's turn. In a new book titled The Feeling of What Happens (Harcourt Brace; $28), the noted neuroscientist not only argues that human consciousness is comprehensible but also offers an arrestingly original explanation of its workings. What makes his views so noteworthy is that they're grounded not in theoretical musings but in years of clinical research on patients who are epileptic or have suffered brain damage through strokes, disease or traumatic injuries.

From these studies, Damasio, who is chairman of the University of Iowa's neurology department, concludes that consciousness is a layered edifice, like some Mayan pyramid or Mesopotamian ziggurat. It is based on an inchoate feeling of self that arises from the brain's detailed "diagram" of the body. Damasio says this diagram, which is continuously revised by the senses, can be thought of as the "protoself"; it props up the rest of the structure.

All kinds of creatures, even ones as lowly as snails, have protoselves, Damasio says, but they aren't really conscious. Consciousness, he explains, requires a nervous system sufficiently evolved and complex that the organism can hold in mind the image of a protoself's moving through and interacting with the world.