Each of us has a unique experience on this earth. A major reason for that is the buildup of our memories over time, which forms the ongoing narrative that we know as our life. Memories are also central to learning. But how does the brain—a collection of cells, neurons chief among them—remember and learn? Eric Kandel, perhaps more than any other person, has unraveled the answer to that question.
Kandel is a Nobel laureate and professor of biochemistry and biophysics at Columbia University. He broke open the investigation of how the brain works at the cellular level, by studying how neurons communicate and change. Born in Vienna, Kandel emigrated to the U.S. as a boy. Fascinated by psychoanalysis, he studied Sigmund Freud, but turned to the nascent field of neuroscience to try to show how the mind arises from the brain, hoping to explain the mind in biological terms. He went to the National Institutes of Health to decipher how memory works, because he felt people are who they are in part because of what they remember. Among other great achievements, Kandel became the first person to record communications between individual neurons in the hippocampus, the brain structure most central to memory. In doing so, he made neuroscience relevant to the average person.
The research path Kandel took was controversial, even dismissed by certain colleagues. He explains how it all played out in an engaging video called Mapping the Mind, created by Joseph LeDoux at New York University, an expert on the emotional brain. The video is the third in a series he is putting together with director Alexis Gambis called My Mind’s Eye. (The first episode featured Ned Block on the mind-body problem, the second video was with Michael Gazzaniga on free will.) LeDoux and Gambis have given Scientific American the chance to post these videos first, on our site.
The conversation between LeDoux and Kandel runs about 12 minutes. Kandel is now 84 yet he is crystal clear, as well as very personable and humble as ever, a pleasure to listen to. Gambis has inserted some lovely footage of Kandel handling the sea slug Aplysia californica, which grow as large as a softball—the creature that allowed Kandel to pin down how memories are stored in the brain. I was lucky enough to be present when Gambis and LeDoux filmed the action and talked with Kandel.
After the interview, the episode transitions into a four-minute music video of the song “Map of Your Mind,” performed by LeDoux’s band, the Amygdaloids. A few highlights from the interview, still fresh in my memory:
2:50 Neuron to neuron. Finding a physical basis for the mind meant Kandel had to pull the brain apart, down to individual neurons, to figure out how they stored and transmitted information. Here he recounts why he began with the hippocampus, the seat of memory.
3:45 Kandel explains why he stopped studying the human brain and turned to the sea slug. The answer: the slug has the largest brain cells of any animal on the planet. Slugs can also be trained, so Kandel could monitor individual neurons and see what happened to them as the animals learned, based on memory of past interactions. Kandel also recalls why colleagues back then said he was wasting his time.
6:30 As technology improved, researchers could get more detailed data about what neurons were doing. Kandel explains how he discovered that learning alters the strength of connections between neurons across synapses—the gaps between the neurons. In short term memory, Kandel showed, only the communication across the synapses is altered. But in long term memory, the synapses are physically altered. This set of observations helped prove that psychotherapy could change the brain and therefore change behavior.
8:00 Kandel describes how he and colleagues went on to determine how genes and protein production are involved in memory.
11:00 Still working today, Kandel briefly describes his latest efforts to clarify the mechanisms of attention, cognition and consciousness. The video ends with a focus on Kandel’s attempts to draw common lessons from neuroscience and art; it includes an odd, unexpected foray into how the two fields have tried to explore female eroticism and aggression.
14:40 Music video, “Map of Your Mind.”
Further reading, suggested by Eric Kandel:
The Molecular Biology of Memory Storage: A Dialogue Between Genes and Synapses. Eric R. Kandel in Science 294: 1030-1038; 2001.
In Search of Memory: The Emergence of a New Science of Mind. Eric R. Kandel. W.W. Norton and Company, New York; 2006
The Age of Insight: The Quest to Understand the Unconscious In Art, Mind, and Brain, From Vienna 1990 to the Present. Eric R. Kandel. Random House, New York; 2012.
The New Science of Mind and the Future of Knowledge. Eric R. Kandel in Neuron 80: 546-560; 2013.
The Molecular and Systems Biology of Memory. Eric R. Kandel et al.in Cell 157: 163-186; 2014
Image from this video courtesy of Imaginal Disc.