Antonio Damasio is one of the most influential neuroscientists of his generation. He has pioneered several of the themes the define the field, including the importance of emotion - we need to feel in order to think - and the embodied nature of the brain. Consider a seminal experiment designed by Damasio, Antoine Bechara and colleagues. It's known as the Iowa Gambling Task and it goes like this: A subject - “the player” - is given four decks of cards, two black and two red, and $2,000 of play money. Each card tells the player whether they won money or lost money. The subject is instructed to turn over a card from one of the four decks, and to make as much money as possible.

But the cards aren’t distributed at random. The scientists have rigged the game. Two of the decks are full of high-risk cards. These decks have bigger payouts ($100), but also contained extravagant punishments ($1250). The other two decks, by comparison, are staid and conservative. Although they have smaller payouts ($50), they rarely punish the player. If the gamblers drew only from those two decks, they would come out way ahead.

At first, the card selection process is entirely haphazard. There is no reason to favor any specific deck, and so most people sample from each pile, searching for the most lucrative cards. On average, people have to turn over about 50 cards before they began to draw solely from the profitable decks. Logic is slow.

But Damasio wasn’t interested in logic: he was interested in emotion and the body. When he devised this experiment in the early 90s, the gamblers played the card game while hooked up to a machine that measures the electrical conductance of their skin. In general, higher levels of conductance signal nervousness and anxiety. What the scientists found was that after drawing only ten cards, the hands of the experimental subjects got “nervous” whenever they reached for the negative decks. Although the subjects still had little inkling of which card piles were the most lucrative, their emotions had developed an accurate sense of fear. They knew which decks were dangerous. In other words, their feelings figured out the game first - the hand was leading the brain.

Interestingly, neurological patients unable to experience any emotion at all - they have a damaged orbitofrontal cortex - proved incapable of selecting the right cards. While most people make substantial amounts of money during the experiment, these patients often went bankrupt, and had to take out extra “loans” from the experimenter. Because they were unable to associate the bad decks with negative feelings - their hands never developed the symptoms of nervousness - they continued to draw equally from all four decks. (If you're interested in this experiment, I highly recommend Damasio's previous books, such as Descartes' Error.)

Damasio has a new book coming out this week, and it's his most ambitious work yet. In Self Comes To Mind, Damasio seeks to explain how the primordial elements of the mind - all these body maps and recursive loops - get transformed into conscious experience, into that metaphysical figment we call the self. It's a lucid and important work, and scrambles all the conventional categories of the brain. It turns out that the "higher" parts of the cortex are inseparable from the "lower" parts, and that "you" - the "you" reading these words - emerge in large part from the brain stem, the nub of tissue just above the spinal cord. We arise, in other words, from the place were brain and body meet, where flesh and feeling are emulsified together. Professor Damasio was generous enough to answer a few questions about his latest book:

LEHRER: In Self Comes To Mind, you write: "I have been studying the human mind and brain for more than thirty years, and I have previously written about consciousness in scientific articles and books. But I have grown dissatisfied with my account of the problem, and reflection on relevant research findings, new and old, had changed my views." Could you explain what scientific findings led to your dissatisfaction? Why did you change your views?

DAMASIO: The scientific facts [that most changed my views on consciousness] have to do with wiring, brain wiring, that is. For example, we now have a good picture of how certain parts of the cerebral cortex are organized as hubs and how those hubs connect with each other. We even know that some hubs are so well connected to other hubs that they manage to link up varied cortical parts in wider networks of higher hierarchy. We also know a lot more about the wiring of brain regions below the cerebral cortex, such as the brain stem. Those regions are not a mere conduit for signals to and from the body. They are active contributors to the brain operations that permit minds and self to emerge.

On the other hand, reflection on the experience of conscious minds also convinced me that feelings need to be given an even more important role in the making of subjectivity. We do not merely perceive objects and hold thoughts in our minds: all our perceptions and thought processes are felt. All have a distinctive component that announces an unequivocal link between images and the existence of life in our organism.

In Self Comes to Mind I address the new facts and explain how they can help us glean mechanisms capable of constructing a conscious brain.

LEHRER: I think many readers will be surprised that, in your attempt to explain the mystery of consciousness, you begin with discussions of the body. Why, as you write, is "the body the foundation of the conscious mind"? And why does the brain stem, this most ancient of brain areas, play such an important role in consciousness?

DAMASIO: That is where having an evolutionary perspective comes in handy. Why do we have a brain in the first place? Not to write books, articles, or plays; not to do science or play music. Brains develop because they are an expedient way of managing life in a body. And why do we, by now, have brains that make minds with selves — conscious minds? Because minds and selves increase the management power of brains; because they permit a better adaptation of a complex organism to complex environments. In other words, organisms equipped with brains, minds and self were selected by evolution because such organisms had better chances of survival, and, eventually, chances of survival with well-being.

The emphasis on the brain stem is closely related to the star role that the body plays in my account of minds and selves. The brain stem nuclei hold the principles and the rules required to manage life in our bodies. The cerebral cortex, on the other hand, ends up helping the organism manage life, according to those principles. That is the heart of the matter, really!

LEHRER: For the most part, scientists have relied on three traditional perspectives to study the mind: introspection, behavioral observation and neurological investigation. You introduce a fourth perspective: an evolutionary framework. But this isn't the standard speculations of evolutionary psychology. Instead, you begin the book begins with an overview of individual cells, which you refer to as a "cartooned abstraction of what we are." What can the self-regulation of cells and their homeostatic mechanisms teach us about the human mind?

DAMASIO: In Self Comes to Mind I pay a lot of attention to simple creatures without brains or minds, because those “cartooned abstractions of who we are” operate on precisely the same principles that we do. They manage life — biological value — like we do. Consciousness lets us discover those principles and lets us realize that they quietly influence (a)the shape and function of our brains, (b)the themes of our minds, and (c)eventually the themes of our culture. In other words, the guiding principles of our minds and selves precede the existence of minds and selves, which is why the likely story of the biology of consciousness does not conform to the traditional and intuitive narrative. Consciousness prevailed because it serves life.

Where consciousness plays a real star part is in the opening of the way into culture. Consciousness permits us to develop the instruments of culture — morality and justice, religion, art, economics and politics, science and technology. Those instruments allow us some measure of freedom in the confrontation with nature.

LEHRER: You write: "Feelings are often ignored in accounts of consciousness. Can there be consciousness without feelings? The answer is no." Why are feelings such an essential part of human experience? And why can't we do without them?

DAMASIO: Feelings, especially the kind that I call primordial feelings, portray the state of the body in our own brain. They serve notice that there is life inside the organism and they inform the brain (and its mind, of course), of whether such life is in balance or not. That feeling is the foundation of the edifice we call conscious mind. When the machinery that builds that foundation is disrupted by disease, the whole edifice collapses. Imagine pulling out the ground floor of a high-rise building and you get the picture. That is, by the way, precisely what happens in certain cases of coma or vegetative state.

Now, where in the brain is that “feel-making” machinery? It is located in the brain stem and it enjoys a privileged situation. It is part of the brain, of course, but it is so closely interconnected with the body that it is best seen as fused with the body. I suspect that one reason why our thoughts are felt comes from that obligatory fusion of body and brain at brain stem level.

LEHRER: On the one hand, some might be worried that a theory of consciousness that posits the importance of homeostatic mechanisms, the brain stem and the fleshy body might see the conscious "will" as an inconsequential force, a puppet to its non-conscious masters. But you argue the opposite, that "the presence of non-conscious processes...amplifies the reach of consciousness." Could you explain?

DAMASIO: Conscious deliberation is in constant dialogue, often a conflicting dialogue, with non-conscious processing. Sometimes conscious deliberation prevails, sometimes not. But the reason why such conscious deliberations elevate human beings above the level of mere puppets of non-conscious forces, is that the instruments of culture to which I alluded above can provide liberating solutions to the problems we face. Sometimes those solutions go against what our unconscious forces would want us to do. Have you ever turned down the chocolate dessert, or, for that matter, the juicy steak with frittes? Of course, you have. You can thank conscious deliberation for that.