Dr. Kandel is University Professor and Fred Kavli Professor and Director of the Kavli Institute for Brain Science at the Columbia University College of Physicians and Surgeons. His most recent book is The Age of Insight: The Quest to Understand the Unconscious in Art, Mind, and Brain, from Vienna 1900 to the Present.
By probing the synaptic connections between nerve cells in the humble sea slug, Eric Kandel has uncovered some of the basic molecular mechanisms underlying learning and memory in animals ranging from snails to flies to mice and even in humans. His groundbreaking studies have demonstrated the fundamental ways that nerve cells alter their response to chemical signals to produce coordinated changes in behavior. This work is central to understanding not only normal memory but also dementia and other mental illnesses that affect memory.
Kandel's research has shown that learning produces changes in behavior by modifying the strength of connections between nerve cells, rather than by altering the brain's basic circuitry. He went on to determine the biochemical changes that accompany memory formation, showing that short-term memory involves a functional modulation of the synapses while long-term memory requires the activation of genes and the synthesis of proteins to grow new synaptic connections. For this work, the Austrian-born Kandel was awarded the 2000 Nobel Prize in Physiology or Medicine.
The traumatic events of Kandel's childhood likely influenced his later interest in the biological mechanisms of memory. He was only eight when, in 1938, Nazi Germany annexed his homeland, but the humiliation and discrimination that Kandel, his family, and other Jews suffered under this oppressive regime were forever seared into his memory. In 1939, on the eve of World War II, his family fled Austria for the United States.
As a college student at Harvard, Kandel majored in history and literature, but he was drawn to psychoanalysis after befriending a native Austrian student whose parents were prominent psychoanalysts in Sigmund Freud's circle. Kandel went to medical school at New York University with the goal of studying psychiatry and becoming a psychoanalyst himself. But thinking that he should know more about how the brain works, he took a neurophysiology course that shifted his interest toward research into the biology of memory. "The cell and molecular mechanisms of learning and memory struck me as a wonderful problem to study … It was clear to me even then that learning and memory were central to behavior, and thus to psychopathology and to psychotherapy," Kandel recalled.
Initially, he focused on recording the activity of nerve cells in the hippocampus, a region of the brain vital to memory formation. The mammalian hippocampus, however, with its seemingly infinite number of neurons and synaptic connections, made it difficult to study learning and memory at the cellular level. Kandel soon realized he needed a simpler system and chose the invertebrate sea slug Aplysia, much to the dismay of his colleagues who thought that no self-respecting neurophysiologist would abandon the study of learning in mammals to work on an invertebrate.
This bold decision paid off, though, and Kandel now works to instill in his students a sense that risk-taking is important to good science. "I try to convey to students my love of science and my conviction that exploring the biology of the brain is an unmatched scientific adventure," he explained. "I also encourage them to think boldly and to work carefully; to take gambles on their ideas and to try new approaches. I also tell them never to be embarrassed in exposing their ignorance … We are all here to learn, and the learning never ends."
More recently, Kandel has expanded his studies of simple learning and memory in Aplysia to include more complex forms of memory storage in genetically modified mice. These studies have focused on explicit memory (the conscious recall of information about places and objects), revealing the importance of a balance of activation and inhibition in memory storage so that animals as well as humans do not store information in their memories that is not important to recall.
Eric Kandel: Reductionism acknowledges from the outset that I’m not looking at the whole picture; I’m only looking at part of the picture. But the reason I’m doing that is because I really want to understand that. Looking at the whole picture is too complicated. So, when Harvey was trying to understand how the body works, he focused in on the heart and he realized that the function of the heart is not to serve as the soul, but to serve as a muscular pump that pushes blood around the circulation. So I know that your heart and my heart is not the seat of my soul or your soul; it’s a pump. Does that make it any less magical? Do I have less respect for your heart or my heart because I realize how it functions? No. Number one.
Number two, once you understand how components function, you’ll want to put it into the context of the body as a whole--what are the major arteries that come out of the heart, how do they feed oxygen to the muscles in the body, etcetera, etcetera, etcetera? So we want to do a reductionism in order to understand particular components, but then as Paul Allen is showing, we need to put the components together. We need a new synthesis. And so we need to put it in a larger context.
So that leaves the residual issue as to what degree does the acknowledgment that all mental function, including my religious beliefs, emanate from the brain. People have difficulty with it. They want to think there’s a mind out there some place that carries on after I’m dead and that mediates a lot of these spiritual values, and I don’t find good evidence to support that as far as I can tell. All mental functions, from the most trivial reflex to the most sublime creative experience, come from the brain.
We have reason to believe that some aspects of free will you are not consciously aware of. I don’t think that necessarily means that you’re not free, but you’re not consciously aware of it. And the background from that comes from a famous experiment that Benjamin Libet did, and I forget when it was, 1971, thereabouts, in which he did a fascinating experiment. He asked subjects to make a decision to move their hand and to indicate by pressing a button when they’re making that decision. And he had electrodes on their head, and it turned out that before I made a decision to move my hand, an electrical potential appeared in my brain that preceded my conscious decision to move the hand. So you can be aware of my wanting to move the hand consciously without my being aware of it. That means the decision was made unconsciously.
Now, when Ben Libet came out with that, it shook up the scientific community. Do you think Freud would have been surprised about that? He said from the very beginning, much of our mental life is unconscious. We now know we make a lot of decisions, we choose our partner in part by unconscious evaluations. There are lots of decisions that are made unconsciously then consciously. Conscious decision-making is very good when there are two alternatives because you can focus consciously very effectively on one thing at a time. If you’ve got a lot of options . . . now this was not my case, but you who have lots of women who are interested in you, probably can choose from many of them. That decision that you have to make is likely to be more effective if you make it unconsciously.
So there is now a whole psychology on unconscious decision-making that is emerging, in part stimulated by Libet’s interest but also a continuation from Freud’s interest.
Directed / Produced by
Jonathan Fowler & Elizabeth Rodd