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 n a recent balmy evening, Dr. Joseph LeDoux, a professor of neuroscience at New York University, strode to the stage of the Cornelia Street Cafe in Greenwich Village and read from his latest book, "The Synaptic Self: How Our Brains Become Who We Are." Astonishingly, the audience — graduate students, publishing executives and scientists — greeted Dr. LeDoux's performance with enthusiasm usually reserved for rock stars. In the world of the brain sciences, Dr. LeDoux, 52, is a star of high wattage. Through his research and writings, he has been a major force in changing approaches to human brain research. Previously, brain studies tended to bypass phenomena that are difficult to measure, like emotions and the unconscious. Dr. LeDoux, in his laboratory, began finding ways to study how the brain processes emotions. Rather than treat emotion as an experience, he looked at it as a process. And in doing this, he uncovered a path into the territory that is the human mind. "I'm studying the quantifiable aspects of the mind," Dr. LeDoux said over coffee on a morning not long after his cafe performance. "I'm saying, `Here's how you can quantify certain aspects of it and make some progress.' " Q. In "The Synaptic Self," you say, "We are our synapses." Why do you say that the key to humanness is to be found in the microscopic spaces between two nerve cells? A. Synapses are the spaces between brain cells. But more importantly, they are the channels of communication between cells that make possible all brain functions, including perception, memory, emotion and thinking. It's practically a truism to say the synapses underlie personality since synapses underlie everything the brain does. More important yet: synapses are the sites of storage of information, including information that is encoded by our genes and also by our experiences — our memories. When it comes to personality, genes and experience are just two ways of doing the same thing — wiring synapses. That's why I say, To the extent that we are a product of our genes and experiences, we are our synapses. This doesn't mean that the essence of who you are is encoded at a particular synapse. It means that your self is a very complex pattern of synaptic connectivity in your brain. Q. Why is this a breakthrough? A. In science, it's often important to define a problem in a practical way before you can make progress on it. Psychological conceptions of the self have tended to be framed in terms not compatible with what we know about the brain. It would be hard, for instance, to track down the neural basis of concepts like superego, narcissism, esteem or actualization. To solve this, I've long felt that scientists needed to come up with a new way of thinking about the self. I do it by attacking it from two angles. One is bottom up. Given that synapses are important to both genetic and experiential aspects of the self, studies of synapses give us a neural anchor to understand how these psychological constructs work. The other is top down. Given that memory is so important to maintenance of the self, and that much is known about the mechanisms of memory, we can use it as a way in to understanding the synaptic basis of the self. Q. What have you done to help us gain this knowledge? A. My work has been focused on the brain mechanisms of emotional memory, a form of unconscious memory formed in a region of the brain called the amygdala. Through studies of fearful or traumatic experiences in rats, my colleagues and I have been able to identify specific synapses that participate in the formation of the memory. Studies of humans have confirmed that the same basic circuits are involved. Q. One area you've specialized in is the biology of emotions. Was there, until recently, a kind of bias among experts against looking at this? A. Oh yes. For years, you couldn't study the mind. At first, the problem was the behaviorists who said, "no, no, no, no" to any mind studies because they felt that observable behavior was the only legitimate psychological topic. What I feel is that we now need is more of a mind science because cognition is about cognition and emotion is about emotion. The mind is about both things. Q. Marvin Minsky, the M.I.T. computer scientist who has written about the mind, believes, to simplify, that we are basically a mass of chemicals and switches. Do you agree? A. That's what the brain is: just a piece of meat that has chemicals and electrical charges. The mind, of course, is a special version of that. And we may not know in our lifetime all about how the brain works to make the mind. What we know about the brain is that it's got neurons that communicate across synapses by releasing a neurotransmitter and that generates electrical impulses and the receiving neuron that then talks to its neighbors the same way. If the mind depends on the brain, then all aspects of the mind are going to depend on these simple electrical, chemical processes. Q. Speaking of meat, is it true you come from a family of butchers? A. Yes, my father was a butcher. As a young person, it was my job to clean the membranes off the brains we sold in the shop. The most vivid image I retain from that time is pulling the bullets out of cows' brains. The way animals were killed was by being shot. And so I'd pull the bullets in order to clean the brain. Often while I was doing it, I wondered what being shot could mean for the cow's mind. Q. How then did you find your way into neuroscience. A. I haven't been a scientist all my adult life. I have two degrees in marketing. I had studied marketing because my parents, small-town people from Louisiana, wanted me to. I was totally uninterested in business and ended up taking a master's in marketing and consumer psychology. As part of that, I took at course at L.S.U. with the late Robert Thompson. So I worked in his lab and we published a few papers, and he endeavored to get me into graduate school at SUNY Stony Brook in New York. That was the beginning. Q. As a student of both the brain and the mind, do you sometimes try to visualize your own brain at work? A. Sometimes, yes. Especially if I'm afraid of something. Let's say I'm walking in the woods and suddenly I see something on the ground. I pause and I imagine my amygdala being driven by that curved shape on the ground. Then I realize that the object is a stick and not a snake and I move along. Yes, I can visualize the whole process. Q. Is being a brain scientist something like becoming an astronaut? You are always entering into completely new areas of discovery? A. No. It's more like a deep sea explorer. When you're studying the brain, it doesn't feel like you are going into open space — more like into a confined space. It feels like you are getting into a ship that can take you down to find those little creatures in the dark depths of the sea. Interestingly, I never find brain studies confining. Every time you discover something and you try to understand it, you know that you've only scratched the surface. Q. In the last few years, we've seen a lot of big-name physicists and even geneticists, take up the brain sciences. Why all this cross-disciplinary migration? A. Brain science has been a favorite one for this kind of migration because the mysteries of the brain are so attractive. So people like Gerald Edelman and Francis Crick have turned to solving problems of the brain. These are smart people. The more the merrier.
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