BLP Conversations: Austin Ratner & Joseph E. LeDoux

Austin Ratner: So, the idea of this series is for scientists and artists to get together and discuss the relationship between the sciences and the arts. Neuroscience has a special relevance to art, maybe, because it studies the organ that makes art—the brain—and a special relevance to the humanities because our brains are what make us human. I’m a fiction writer, but I have a medical training and almost became a neurologist. You’re a neuroscientist who is also a musician. What kind of music do you play?

Joseph E. LeDoux: It’s rock music, but it’s all about the research really. It’s about the mind and brain and mental disorders—like most rock songs, in a way. The band’s called The Amygdaloids.

AR: Neuroscience is such a fractious field, where people seem embedded in one way of looking at the mind or the brain and unable to put that way together with others. I thought your book Synaptic Self did such a nice job integrating so many different observations and ideas about the brain. There was an exciting intellectual openness to the book in that regard. And you’ve titled one of your songs “Mind Body Problem.” Do you agree that people have a difficult time putting ideas of mind and brain together?

JL: You mean readers?

AR: Yeah, and scientists.

JL: Well, scientists sometimes have trouble with it.

AR: And poets, as well. There’s a whole anti-science movement within the humanities that I associate with postmodernism. It goes back to the Romantics.

JL: I think you find a lot less of that these days. My wife’s an art critic and we have tons of friends who are artists and they’re just soaking up as much science as they can. We have an artist in residence in my lab who’s been there for years and, in general, if I go to an art opening and artists find out I’m a neuroscientist, they’re eager to talk about it. In some academic circles I think you’ll still find that kind of distrust of science, but it’s much less common in practicing artists.

AR: And what about scientists?

JL: Scientists are more narrow-minded. It’s interesting to go to panels on, say, art and the brain. The artists want to learn from the scientists. And the scientists want to tell the artists how it works.

AR: As a writer and somebody who had an interest in studying the mind from a hardcore neuroscience point of view, it seems to me that the mind and brain are not at odds with one another. And the introspective lens—I think you say so in Synaptic Self—is another way of looking at the same phenomenon, the single phenomenon of the mind-brain unit. Introspection is a particular lens and it’s an important lens for art and for our relationships to other people, obviously. That’s the medium through which we communicate our experience. What do you think introspection has to offer the neuroscientist, if anything, and vice versa?

JL: I’ve been working on a paper called “Coming to Terms With Fear” [Ed note: JL’s inaugural address on his induction into the National Academy of Sciences, forthcoming in PNAS, Proceedings of the National Academy of Sciences]and it’s about the problems with the term “fear.” Fear is a feeling we know from our introspections, but what I study is the way the brain detects and responds to threats, and those responses are distinct from the subjective experience of fear—they’re contributing to fear, but they’re not the same as fear.

In this paper I suggest the feeling of fear comes about in the brain in much the same way the character of a soup comes about in the pot. When you make soup, you begin with a bunch of ingredients, none of which are soup ingredients—they’re just ingredients in nature. You mix them together, and you throw in some chicken and carrots and onions, and you’ve got a basic chicken soup. If you put in some roux, you can shift the mixture towards gumbo. If you put in curry paste, the mixture goes in a different direction. Synaptic transmission, plasticity—these are just neural ingredients found in a variety of different mental states. The particular ingredients that occur together can give you a feeling of fear, or other emotions with different ingredients. The same is true for variations of fear. We have thirty-seven words in English for different variants of fear and anxiety.

AR: And the particular organization of the same ingredients makes a difference. Carbon and hydrogen and oxygen can combine in different patterns and amounts and ratios to make many different molecules with vastly different functions. I imagine that the response to a threat might look similar across many species in terms of the chemical ingredients, but the subjective experience of that threat-response, and whether it’s a conscious feeling like humans have, would depend on the organization and complexity of the animal’s brain.

JL: Right. All animals have to be able to detect and respond to threats. Within mammals the circuitry is very similar. Within vertebrates the circuitry is also conserved. Invertebrates have different circuits, but the molecules involved in so-called fear-conditioning in a rat are the same as those in fear-conditioning in an aplysia (sea slug). Even a bacterial cell has to be able to detect and respond to threats in its environment. It has no neurons, no circuitry at all, but it can identify a toxic element in its environment and wiggle away from it. Or it can identify something that’s nutritional and incorporate it inside the cell membrane. There’s even evidence now that single-celled organisms can undergo associative learning through molecular encoding. Single-celled organisms do not have neurons, of course, but they do possess functions that are precursors to those functions seen in neurons. For example, the action potential (the electrical impulse that moves along a nerve) is believed to have arisen in unicellular organisms as a way of repairing the cell wall.

AR: Oh, interesting.

JL: Something damages the cell wall; if the cell can create an electrical spark there, it attracts nutrients from inside the cell to the cell wall and helps repair it. That is a form of electrochemical signaling that takes place inside a single cell. But a multicellular organism applies the same kind of electrochemical signaling to the task of cell-to-cell communication. The nervous impulse moves across cells, and then you begin to have an actual neural element. . . . My friend in Scotland, Seth Grant, is interested in the evolution of synapses. He finds building blocks, for example, of the NMDA-receptor complex in single-celled organisms. To get from the biochemistry of a single-celled organism to a mammalian nervous system, it’s just a matter of using those building blocks to assemble the NMDA-receptor complex and all its glorious manifestations in multicellular organisms.

AR: It’s fascinating.

JL: Work now on SSRIs is being done in plants because they have serotonin and serotonin receptors. All of these things that we think of as the Holy Grail of mental life were already there, long ago in evolutionary history, maybe even at the beginning.

AR: Well, sometimes it gives me anxiety to feel I’m really a plant. Do you ever feel that?

JL: I guess I have other versions of the same sort of thing.

AR: You know? The idea that I’m really no different from a robot or a plant. That spooks me. Since I’m speaking to a fear expert, you can tell me, is that normal?

JL: Perfectly normal!

AR: That’s one way that some people in the humanities or the arts can get scared about science. They use the word “reductive.”

JL: Right.

AR: People don’t want to feel that they’re just reduced to just molecules and cells.

JL: But they aren’t. They aren’t.

AR: Your analogy to soup—to me that’s an analogy about emergent properties.

JL: Right.

AR: And the concept of emergent properties is something that I hold onto. It makes me feel better.

JL: Most scientists probably aren’t reductionists. They’re interactionists. You have multiple levels of structure in an organism. And findings about the gene can inform your knowledge of behavior just as findings about behavior can inform gene research. So it’s not about eliminating levels, but understanding how the levels interact. It’s not about getting down to the gene and stopping there. If you get to the gene you have to go back to the top.

AR: Right. And it seems to me that even if you can take an inquiry down to the level of the atom, you don’t necessarily want to. Meteorologists know that an ocean is made of molecules of H2O, but they need to know about water’s emergent properties, about how water molecules behave en masse. When I was in high school, I used to think like a dualist. I needed to imagine there was a soul. I don’t really need that dualist idea anymore, personally. But I do need this notion of emergent property—maybe for spiritual reasons, but more so for explanatory ones. There’s something distinct about the molecules en masse, once they’re built up into a brain.

JL: I think maybe you’re using “emergent property” in a way that’s slightly more “soul-like” than I am. For me, the notion of emergent property never leaves the physical realm.

AR: No, no, I agree with you. I look at it like this: the ocean is made of molecules of H2O, but three molecules of H2O can’t make a wave. Only large numbers of them together can make waves. And a wave is an actual concrete physical phenomenon but it’s also a concept distinct from what you can see about water on a molecular level. So that really is all I’m saying. Molecules have different functions in aggregate, depending on how many there are and how they’re organized.

JL: People don’t have a problem thinking about a wave as a product of the molecular character of H2O, but as soon as we start talking about the mind, we turn it into this other thing, where we still imagine a little homunculus with free will behind the molecules, pulling strings.

AR: But I think your book seems to show that the brain is like a wave, made out of the functions of all the individual molecules, even though it does amazing, unique things.

JL: That’s how I look at it.

AR: And it’s not necessarily a bad thing. It just is what it is.

JL: Right. Exactly.

AR: And just as a meteorologist doesn’t use a microscope to study the ocean, I don’t use a microscope in my thinking about the mind. I think of novel writing as a kind of observation of human experience and human being through a wider-angle lens than a neuroscientist would use. It’s one of those introspective lenses. To me, psychoanalysis is another one. Your book Synaptic Self takes note of some of Freud’s contributions to neuroscience, such as being one of the early theorists of synapses. I think some people don’t want to acknowledge his accomplishments as a neuroscientist because they’re so intent on distancing themselves from what they see as his sex obsession or his craziness.

JL: Right. I mean, he had some obsessions that were off the scale, but he had a lot of insights and contributions. I wrote something for a psychoanalytic journal not too long ago that was celebrating Eric Kandel’s life and his contributions to psychoanalysis; Kandel wrote a couple of big papers on psychoanalysis.

AR: Are you talking about “A New Intellectual Framework for Psychiatry”?

JL: Yeah. Exactly right. There were two of those papers.

AR: Yeah, okay, I read those. And his criticisms of psychoanalysis in there, I find to be cogent criticisms—

JL: Yeah.

AR: The way that psychoanalysts can act like a guild rather than like scientists—to me it seems like a shame, because some of the insights of psychoanalysis I think are being lost on people that could use them—basic concepts of “denial” and other introspective concepts about how the mind works. It seems to me that there’s no need to cut yourself off from those simply because other things that Freud said were wrong.

JL: Oh sure, yeah.

AR: Or because you’re interested in the molecules and cells. The whole direction of our conversation is about how the two ends of the spectrum of investigation are not incompatible with one another.

JL: In the afterword in this psychoanalytic tribute book to Eric Kandel, I wrote about the neuroscience perspective on different aspects of the unconscious. We can think of the preconscious, for example, as this hippocampal declarative memory that’s in an inactive state. It’s not being retrieved but it can be retrieved. Then consciousness is when you retrieve that information into working memory and it’s just there and present.

AR: That was one of the major things in your book that was very clarifying for me, thinking about working memory as consciousness, basically.

JL: Rather than “as consciousness” it’s probably better to think of it as a necessary step or a kind of platform, because you know, philosophers get very particular about the difference between access to information and the qualia of experience.

AR: Yeah—I was going to ask you about qualia, the notion of qualia being, I guess, that subjective experience is its own irreducible phenomenon in some way? Do you think qualia is a valid concept? Because it seems like there’s a little bit of a flavor of dualism to it.

JL: Qualia—I think it defines the problem in a way that maybe we’ll have to replace in the future, but it definitely lays out what we haven’t achieved in neuroscience and, maybe, what we’ll finally achieve is an understanding of where the experience is.

AR: One thing that I do find puzzling about trying to give an account of the mind that’s from the molecules and cells up is: there’s a kind of circularity or something about it that bothers me. Because if I’m starting with molecules and cells in building up a picture of something, I’m really starting with an idea of molecules and cells.

JL: Right.

AR: So I’m actually starting with something that is, already to begin with, in my working memory. It is an idea to begin with. You know what I mean? It’s hard for me to get outside of this circular logic.

JL: Well, I mean, that’s the perennial problem. Talking about the mind is different than talking about the unobservable things in physics.

AR: Right.

JL: When we’re talking about the mind, the thing that’s talking about the mind is the mind.

AR: Right, exactly. That’s the sort of tautology of it. It’s like looking at opposed mirrors. It makes me start feeling crazy. It makes you feel that way, too?

JL: Sure!

AR: Does it? Really?

JL: Yeah. I don’t have the answers!

AR: You’re supposed to know everything! It’s a similar kind of existential discomfort to the feeling I get when I think that I’m not much different from a plant or a robot. The book I’m working on now is a novel about robotics, and in doing the research for it I encountered these guys Ray Kurzweil and Hans Moravec, who are Singularity theorists. They talk about Moore’s Law and make this assumption that since computing power increases exponentially and human intelligence stays the same, robots are going to get smarter than humans and it’s going to happen soon. But when you say there’s evidence that even a unicellular organism can learn, it seems to suggest that roboticists may underestimate the computing power of DNA and organic tissue. Because the parallel as far as I can tell is not between a neuron and a transistor, it’s more like between a neuron and a computer. A neuron itself has the capacity to learn or compute. Would you agree with that? What is the computing power of a neuron?

JL: Another way to say it is that the transistor may be more equivalent to a synapse. Each neuron has many thousands of synapses and they can come from many other neurons, so the same neuron can do a thousand different things depending on what its inputs and its outputs are.

AR: Hans Moravec wrote in Scientific American in 2008 that at the present pace of growth in computing power, only about twenty or thirty years will be needed to “close the gap” between robot and human brains. That’s a pretty bold statement. He says the vertebrate retina processes 10 million detections of an edge (a boundary between light and dark) every second. And since robots need to execute about one hundred instructions to make a similar detection, he figures that a retina needs to execute the equivalent of 1,000 million instructions per second (MIPS) . This is his first assumption. Then he says: “The entire human brain is about 75,000 times heavier than the 0.02 gram of processing circuitry in the retina, which implies that it would take, in round numbers, 100 million MIPS (100 trillion instructions per second) to emulate the 1,500-gram human brain.”

JL: That assumes that the brain is a big retina. At each level above the sense organs, you’ve got interactions that are going to make the brain more and more complex. And you’ve got not just the retina but also the cochlea, all of the other senses that are coming in, that are doing their own thing. Then, once the various forms of sensory data get into the brain, they’re all interacting, which expands the complexity of the brain far beyond a simple linear extrapolation from the retina.

AR: Right, right. If intelligence were measured by weight, you could pile up 1,500 grams of fish eyeballs and ask them to give an opinion on the federal budget. The way Moravec correlates the notion of an instruction in a computer with neuronal activity of a certain kind also seems a little crude to me.

JL: It does, yeah.

AR: So I was just curious to get your reaction to this theory. Because that’s another anxiety I have. Do I have to be afraid of the Singularity? And the robots coming and writing my novels for me? I don’t care if they kill me, I just don’t want them to make my work irrelevant.

JL: I mean it’s provocative. And you know it’s good to have provocative people making us think.

Joseph E. LeDoux is the Henry and Lucy Moses Professor of Science at NYU in the Center for Neural Science, and he directs the Emotional Brain Institute of NYU and the Nathan Kline Institute. He is also a Professor of Psychiatry and Child and Adolescent Psychiatry at NYU Langone Medical School. His work is focused on the brain mechanisms of memory and emotion and he is the author of The Emotional Brain and Synaptic Self. He has received a number of awards, including the Karl Spencer Lashley Award from the American Philosophical Society, the Fyssen International Prize in Cognitive Science, the Santiago Grisolia Prize, and the American Psychological Association Distinguished Scientific Contributions Award. LeDoux is a Fellow of the American Academy of Arts and Sciences, the New York Academy of Sciences, and the American Association for the Advancement of Science, and a member of the National Academy of Sciences. He is also the lead singer and songwriter in the rock band, The Amygdaloids.

Austin Ratneris author of the novels The Jump Artist, which received the Sami Rohr Prize for Jewish Literature, and In the Land of the Living. His nonfiction has appeared in the New York Times Magazine and his short fiction has been honored with the Missouri Review Editors’ Prize. Before turning his focus to writing and attending the University of Iowa Writers’ Workshop, he received his M.D. from the Johns Hopkins School of Medicine and co-authored the textbook Concepts in Medical Physiology. Ratner grew up in Cleveland, Ohio and now lives in Brooklyn, New York with his wife and two sons.

Up next in the BLP Conversations series: Critically-acclaimed poet Tom Sleigh and Charles L. Bardes, physician and author of Pale Faces: The Masks of Anemia, the first book in the BLP Pathographies series, will explore the way myths influence their psyches. (April 23, 2014)