Christof Koch Interview: Conversations with History; Institute of International Studies, UC Berkeley

Consciousness and the Biology of the Brain: conversation with Christof Koch, Lois and Victor Troendle Professor of Cognitive and Behavioral Biology at Caltech, March 24, 2006, by Harry Kreisler

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One of your main projects in the last few years is covered in this book, The Quest for Consciousness: A Neurobiological Approach. What I first want to ask you is to talk about your collaboration with Francis Crick, because I know that the two of you working over a number of years came to define a kind of intellectual frame. Talk a little about that intellectual process between the two of you.

Francis, the way he works, he never had a lab, he never worked with a large number of people at any given point in time. He worked with one or two people, most famously, of course, was Jim Watson, and then also with Sydney Brenner, with Graeme Mitchison. book coverWe worked for almost twenty years. When I moved from MIT to Cal Tech in '86 we started to interact and we met on a monthly basis to talk about the brain, and then in 1989 he started becoming very intensely interested, because there was a certain neurobiological discovery -- we became very interested in that and we thought maybe this would be one of the critical features -- a signature of consciousness in the brain.

I think what Francis appreciated about our interaction -- well, the energy level, but also, because he's such a well-known person, many people didn't criticize any of his ideas, and he wanted to be criticized. He was prodigious at throwing out ideas. Some were very smart, some were very perceptive, some were not so, some were just crazy, but you know, you have this fantastic person, this creative genius, who can just throw out these ideas, and he wants a sounding board to tell him, well, this isn't going to work, this is really great but this is totally silly, and really have a give or take over many, many hours. That was his style of working, that you came in the morning and from ten o'clock 'til six o'clock you would just discuss papers, he would go through the evidence, he would sift the data, discuss it, look at it from different light, reject it, have a hypothesis, reject it again, then dinner, and then usually after dinner that process would continue. He kept this up 'til essentially the day he died.

We're on the threshold of a revolution in the biological sciences on the question of how the brain works and the biological basis of consciousness. This collaboration was the formation of a theory which could be tested by empirical research. Is that a fair way to look at the article that resulted, which you published in Science and Nature, laying out an intellectual framework?

Unfortunately, it's too ambitious to call it a theory. It's a framework. There's a difference. A theory is something much more solid where you can make very specific predictions, like the theory of relativity. This is more a framework for approaching the problem in a way that allows you to sustain a research program at the end of which you will understand much more about consciousness, and hopefully -- that's a hope right now, a fond hope -- that ultimately you will solve the problem at the heart of the classically conceived mind/body problem, namely, how do feelings get into the world? How is it that the physical system, like your brain or my brain, can have feelings of pain or pleasure? Of being me? Of being angry?

Now help us understand -- I think we know what consciousness is, or people think they do, but explain that. You refer to Searle's definition, but help us understand what the "it" is that you're trying to characterize, and then find the sources of that in the biology of the brain.

John Searle said that consciousness, what you have -- when you wake up in the morning you have it, and you have it all day, and then it goes away when you go into deep sleep, and then in dreams, of course, you also have it. So, it's the most fundamental feature of the world. It's the way we experience the world. When I feel pain or feel pleasure, I see you, or I'm angry, or I know I'm Christof, I know I'm going to die -- those are all conscious sensations. Philosophers have the term "qualia," so consciousness is made up these different qualia, and that is fundamentally how we experience the world. To experience the world means to be conscious of it.

It turns out there are many things that I can do in my body -- in fact, most of the things I do -- without having any conscious access to them. My digestive system works wonderfully without me knowing about it. There're a hundred million enteric neurons down in your gut, a hundred million. We're not conscious of them. When you run, when you climb, when you dance, when you drive a car, when you bike, you're doing things effortlessly. When you run down a mountain, you run very quickly and you have no idea how you're doing it, you're doing it unconsciously. When I talk, it's not that a person, a "Christof," in my head puts these words together, and then in German or English, in the verb and the adjective and sends it out. No; I have a vague idea and the next thing, I hear these words coming out of my mouth. So, we know there are many things, in fact, the majority of things in my brain, I don't have conscious access to. Certain things I do have conscious access to. What's the difference? How is this possible?

You refer to this as kind of a "zombie" effect, not the consciousness but these things that we do automatically.

We have all these zombies that we use all the time. In fact, life wouldn't be possible without these zombies in our head. This makes interesting research projects because I can now ask at the neurological level, at the brain level, where's the difference between those systems that mediate my zombie behaviors and those systems that actually require consciousness?

It's a scandal -- and Francis always felt this -- it's a scandal that science leaves out consciousness. It's less today, but certainly ten or twenty years ago, when we started, many scientists, probably the majority, said, "Well, consciousness: we've got to leave that to the religious people, we've got to leave that to the philosophers, we've got to leave that to the New Age cult. That's not something scientists can study." But that's silly. We are conscious and I believe it's the most essential aspect of my life, it's the fact that I'm a conscious being, and if I leave that out, then I will forever deprive science of one of the key aspects of the natural world.

We claim it's a natural phenomenon, it exists not here, but it seems to exist here, so if science has ambition that it wants to describe everything in this universe, then it has to describe consciousness. In other words, it's just a cop-out. Yes, it's difficult, it's different than trying to have a theory for how mass is derived, but it's nonetheless a natural phenomenon and we should study it as scientists.

One is able to do the experimentation now. Why? Because of all the new technologies that are coming on board that are allowing us to look at the brain?

Yes. We can now routinely monitor individual nerve cells in animals. See, you have to understand: if you want to understand chemistry, or if you want to understand physics, you need to know about atoms, and you need to know about molecules, and you need to know how they interact. You can't do chemistry without knowing about molecules. Likewise, if you want to understand consciousness or perception or memory or thought, and what happens if these go wrong in mental diseases, you need to know about nerve cells, you need to know how they interact.

Today, in 2006, better than before in any point in history, we can monitor nerve cells, we can listen to them, we can record them, we can stimulate them, we can do all sorts of things, both in animals as well as in humans. In humans it's much more difficult, of course. We have brain imaging, which is cool, but it's a very low spatial resolution. But we have all these tools that enable us now to begin to monitor the brain at the appropriate level of resolution. And so now we think it's time to start having experiments, and people are doing it, to study the neural basis of consciousness.

Another challenge, I guess, is to devise the experiments, to create reactions and then put this together, what we're now able to see. Is that the name of the game here?

Yes. This is what scientists do. I try to do the right control, do the correct experiment. As I mentioned before, it may take many years to figure out some fact about the brain basis of consciousness.

Is there a thumbnail sketch of the brain that you could give a general audience, where the most exciting points of direction seem to be in your research?

You want some explanation of the brain?

Let me rephrase it. Let's begin talking about what your hypothesis is about how the brain works at this point of consciousness. What are the hypotheses that help give you an organizing sense of how to look for things?

Okay. First of all, the overall approach that we advocate that most people do is to study what people abbreviate as NCC, the neuronal correlate of consciousness. Those are the minimal brain -- the minimal because we know your entire brain is sufficient to produce consciousness, it does it each and every day. But do you really need your eyes to see? Well, I can dream. My eyes are closed and I dream perfectly from visual images. I can close my eyes and I can visualize, so I don't need my eyes. Do I need my cerebellum? Probably not for visual consciousness or probably not for any consciousness.

So you can ask the question, what are the minimal set of mechanisms in your head that you need in order to be conscious? Is there a specific neuro-signature, are there specific types of neurons, is there a particular type of neural activity, are there particular types of molecules, particular types of synapses, do they sit in a particular part of the brain? You can ask this whole set of questions, and the name of the game is to try to isolate those mechanisms to really hone in on these neurons in this particular configuration. We talk about coalition of neurons; you have to imagine. The brain has a very, very, very large number -- there are roughly 50 to 100 billion nerve cells, and each one is like a little computer. Neurons are not dumb, like a transistor. They're very "smart," they're very sophisticated, each nerve cell, each neuron, and you have 100 billion of them.

Consciousness may be a coalition of neurons, a little bit like in a democracy where you have coalitions that form, and that assemble and then disasssemble, except the time scale is not years like in an American electoral system, but a fraction of a second. And so, for a hundredth of a millisecond you may have this coalition of five million neurons, and they make in code -- they may give rise to a feeling of "darn it, I'm late today," and then this is suppressed because then there's this other five million neurons, or ten million neurons, who now give rise to the "oh, I see my daughter over there," and then the fact that I'm late, if I get there and I become conscious of my daughter, and those neurons in the brain that represent my daughter fire and they are -- well, this now depends exactly on your philosophical predisposition. Some people say the firing of these neurons is identical to consciousness. Some people say, "Well, it correlates with consciousness; those are the things that we don't know." But what we try to do empirically [is ask] where are those neurons? Can you track them, can you catch a brief picture of them using some fancy imaging technique? Can you influence them?

Very often, a scientist can just observe. So, for example, a function of brain imaging -- I put you in a magnetic [resonance imaging scanner], I show you faces, and I see every time you look at a face, this part of the brain lights up. People do that routinely. So that's observation, that's correlation. What I would then like to do -- I would like to move to causation, where I can influence. What happens if I can put a probe in your brain like a neurosurgeon does during neurosurgery, and I can stimulate that particular part of the brain? Will you then see a face? Again, we can begin to do those experiments quite well in animals, and we can also do them in certain contexts, for example, in a neurosurgical context with humans, where we can actually begin to intervene with the brain.

Next page: Visual Consciousness

See also the Interview with John Searle (1999): Philosophy and the Habits of Critical Thinking

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