🧠Dive into the mysteries of consciousness with neuroscientist Kristoff Koch and Sam Harris! 🌌✨
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I'm speaking with Kristoff Koch. Kristoff is a neuroscientist at the Allen Institute and at the Tiny Blue Dot Foundation. He's the former president of the Allen Institute for Brain Science and a former professor at Caltech. He's the author of five books, most recently "Then I Am Myself the World: What Consciousness Is and How to Expand It," which is the topic of today's conversation.
Kristoff and I speak about his development as a neuroscientist, his collaboration with Francis Crick, their studies of the visual system, change blindness and binocular rivalry, the significance of sleep and anesthesia for consciousness studies, the limits of physicalism, non-locality and other quantum mechanical phenomena, brains as classical systems, the possibility of conscious AI, idealism and panpsychism, Integrated Information Theory (IIT), what it means to say that something exists, the illusion of the self, the possibility of brain bridging that is connecting two human brains in a shared experience, Kristoff's recent experience with psychedelics, and other topics.
This is the deep end of the pool with respect to the scientific understanding of consciousness, and I certainly enjoyed it. And now, I bring you Kristoff Koch.
I am here with Kristoff Koch. Kristoff, thanks for joining me.
Thanks, Sam, for having me. You've written a wonderful book. Your most recent is "Then I Am Myself the World: What Consciousness Is and How to Expand It." I want to kind of follow the line you took in your book here, which traces the evolution of your thought as a scientist focusing on the nature of consciousness. You’ve had a very productive career as a neuroscientist and you had a very fruitful collaboration with Francis Crick. Late in your career, you took the first-person side of things with both hands and have had some experiences with psychedelics that have put pressure on your ontology. I would just love to talk about all of this. Perhaps you can start somewhere near the beginning. How is it that you came to focus on consciousness? You started out more as a physicist. What led you to the study of consciousness?
So, I did get a minor in philosophy in Tübingen, which is a 550-year-old university in Germany, and I did grow up reading Schopenhauer and Immanuel Kant. I've always been interested in consciousness—that voice inside the head. How is that voice compatible with everything else we know? I grew up reading physicists including Schrödinger; they all wondered. They also had similar questions. In fact, both Schrödinger and Heisenberg were very explicit: before I can be a physicist, I am a conscious being that sees, that thinks. Going back all the way to Descartes, before I can even read an oscilloscope or read an instrument as a physicist, I depend on my conscious sensation. Consciousness has to be at the center of our explanation of everything in the world.
I was puzzled when I first came from physics into neuroscience. My PhD was in computational neuroscience. I was puzzled when I really went deep and became a full-time professional neuroscientist that consciousness at the time was simply not discussed. It didn't figure in the index. If you got the standard textbook, you went in the index under "consciousness"—nothing. It was simply ignored. It was all about behavior and neurons, which is fine, which is what I dedicated most of my life to. But ultimately, we also have to explain the puzzle at the heart of our existence: the fact that I'm not just a behaving thing. I actually see, I hear, I dread, I fear, I dream, I desire, I want. So how do all of these things get into the world?
Then I met Francis Crick. I did my PhD in Germany, then went to do a postdoc at the Artificial Intelligence Lab at MIT. Previously, I'd encountered Francis Crick, who at the time had shifted from molecular biology where, with Jim Watson, he decoded the molecular code for life and deciphered the double helical shape of the DNA molecule. But then he shifted because he was also interested in consciousness. The two of us got together and then wrote roughly 20 papers over the next 14 years where we really initiated sort of a modern empirical program to discover the footprints of consciousness in the brain. The argument was very simple: never mind about all the philosophy; we aren't going to converge anytime soon. Let's just focus. We all agree today it's not the heart as most people thought—it's your brain that's sort of the organ of consciousness. So which particular bits and pieces of the brain? Is it the spinal cord? Is it the cerebellum? Is it the retina? Is it the thalamus? Is it the cortex? Does this bit of the brain sort of underlie or serve as the substrate of consciousness? Does it have to oscillate? Does it have to buzz at a particular frequency? Which genes are involved? Which cell types are involved? Is there sort of a conscious mode and an unconscious mode? These are all questions that we felt would have an answer no matter what your philosophical predilection is. There will be an answer of the sort: these neurons in this state in that part of the brain at this time express the fact that I see or that I hear, and it's causal. In other words, if I can activate those neurons or if I can put these neurons into this particular buzzing state, for instance, then you should have a conscious experience. Conversely, if I can somehow interfere with this neural mechanism by a drug, by a neurosurgeon’s electrode, by some external magnetic device, then you shouldn't have the experience. This is sort of the modern program to study the footprints of consciousness—now called the neuronal correlates of consciousness or the NCC in patients, in neurotypical volunteers, in animals like mice and monkeys and rats and other animals.
I recognize that you are someone who always took the so-called hard problem of consciousness seriously, which is to say you thought it was a non-trivial mystery. I remember Francis Crick's approach to this; he wrote a book, "The Astonishing Hypothesis," way back when. I remember him being more of an arch-materialist—the mind is simply what the brain is doing, right? You're just a pack of neurons. From what you just said, it sounds like you sort of tabled your philosophical differences and just decided to go look for the neural correlates of consciousness. We agree about that whether we agree about anything else in philosophy. Was that an impediment to your collaboration with Crick at all, or do I have Crick wrong?
No, you don't have him wrong. That was the starting point. That was the explicit starting point—that once we understand neurons and their vast complexity, an untamed complexity that's incomprehensible to us, Francis was very clear. He said this hypothesis may not be true; there might be other ways we have to think about it. He was sympathetic. For instance, very early on, we encountered Jerry Edelman, who explored the possibility that maybe it has to do with complexity. An early influential paper called "Consciousness and Complexity" argued that complexity had to be involved, which is a little bit more than just saying it's just a bunch of neurons. The most widespread belief among neuroscientists is, well, it's an emerging property just like wetness emerges from water. But then we also, Francis and I, realized that’s inadequate because you have some structures like the cerebellum. You can lose these neurons—you will be impaired—but basically, you stagger about, you look like you're always drunk, but basically all these people, these patients who have lost part or all of their cerebellum, they see, they hear, they dread, they fear, they imagine. Their consciousness is essentially, to first order, unchanged. It can't just be the number of neurons; it has to be the way they are organized. Same thing with the spinal cord. You can be quadriplegic; you’ve just lost all your spinal cord, 200 million neurons, right? So you can't move, but again, your consciousness hasn't really changed that dramatically. Francis’ hope was similar to what he had accomplished in molecular biology, that if we look at the right neuronal mechanism in the right way, then suddenly it’ll become apparent. Of course, we didn’t find such a simple explanation, and he was always open to the possibility that other ways of conceiving of it may be necessary to finally understand it.
I should say that anyone who has seen me try to type on my phone will wonder whether I have lost my cerebellum in some terrific accident. A few people are born without a cerebellum altogether. I can confirm I do have one, having done my fair share of MRI experiments.
👀 Your brain's dance: See Biden, then Trump—binocular rivalry in action! 🌀🔄
In our discussion, Kristoff continued to delve into the intricacies of consciousness by exploring phenomena such as binocular rivalry. This is where you project two different images—say, one of President Biden into one eye and one of Donald Trump into the other. If done correctly, you'll only see Biden for a few seconds before he fades and Trump appears, and then it switches back again. It's a NeverEnding dance where the inputs to your nervous system remain stable, yet you experience a bizarre shifting between the two images.
Kristoff explained how scientists track this phenomenon throughout the visual system of monkeys. They identify the first stages where neurons respond not just to the input received by each eye but to what the animal actually sees. Using advanced techniques like optogenetics, they trace the neural footprint of visual consciousness through the brain.
Another fascinating area Kristoff touched on is the distinction between being conscious and not being conscious, such as during sleep or anesthesia. When someone is anesthetized, you can observe changes in neural activity as they lose and then regain consciousness. However, this raises the complex issue of differentiating between a true cessation of consciousness and merely a loss of memory. For instance, while you are anesthetized or in deep sleep, you become paralyzed and lose memory, but are you truly unconscious?
He referenced studies where subjects with high-density EEGs were asked to report their experiences just before waking. Remarkably, even in deep sleep, 30% of people report dreamlike experiences, although these are typically less structured than those during REM sleep. Conversely, during REM sleep, 80% of people report having dreams. These findings challenge our understanding of sleep and consciousness, suggesting that even in deep sleep, the brain is far from being entirely offline.
Kristoff also brought up the philosophical controversies surrounding theories like Integrated Information Theory (IIT) and the eliminative materialism championed by thinkers like Dan Dennett and Paul Churchland, who argue that consciousness itself is an illusion. He countered this by asserting that consciousness is the one thing about which we cannot say this, as any illusion presupposes a conscious experience. This, he argued, is a fundamental flaw in physicalism, which struggles to explain how subjective feelings emerge from mere atoms and void.
He drew an analogy to complex scientific concepts, suggesting that just as a dog might never understand general relativity, some aspects of consciousness might also be beyond human understanding. He pointed out that quantum mechanics, a field full of puzzling phenomena, similarly defies easy explanation, emphasizing the profound challenges in defining what is physical.
This is the deep end of the pool with respect to the scientific understanding of consciousness, and I certainly enjoyed it. And now, I bring you Kristoff Koch.
🧠Consciousness: A mystery even if God says it's just brain waves! 🤯✨
Something seems to be left out, Kristoff began, that we have this intuitive impasse that doesn't suggest or, much less, prove that it isn't simply so. We just may be in a bad position to think about how consciousness emerges, and it may always seem like a miracle even if we had the answer in hand. Imagine if it was just 40 Hertz oscillations in thalamocortical loops—if that was the answer and God told us that's how it happens. Well, it may always just seem like a brute fact that doesn't actually explain anything.
At the bottom, at the rock bottom of physicalism, he continued, is how do we define the physical? If you listen to anything in quantum mechanics over the last 30 years, we all know it's deeply troubling and very difficult to define what is physical. The fact that the physical includes such bizarre things as two particles that are entangled at opposite ends of the universe—if you observe one and determine its state, instantaneously the state of the other is determined. What sort of physicalism is that if things are entangled across the universe? The mere act of observing creates reality—how does that sit with standard physicalism?
Brains are warm and wet, he remarked, so it's irrelevant, but now we've learned over the last 10 years that they can find entanglement in all sorts of soft matter systems. This interesting phenomenon that xenon, a rare gas, acts as an anesthetic. Different isotopes of xenon, although chemically the same with eight outer electrons, don't interact. They're called noble gases because they are so non-reactive. However, it turns out those that have a nucleus spin of 1/2 have a different anesthetic potency in mice. This is what we're investigating in flies, in cerebral organoids, and in primary cultures. If this is replicated, it would seem to indicate that something as subtle as nuclear spin actually makes a difference at room temperature in these organisms.
I think we will probably build humanoid robots that fully pass the Turing test, Kristoff speculated. Once we get out of the uncanny valley with them, they'll certainly seem conscious to us because we'll build them to seem conscious. They'll talk about their experiences and emotions, and they'll be very attentive to ours—better judges of that than probably any person we've met. We will effortlessly slide into this sense of being in a relationship with these entities, and we will still not understand the neural basis of consciousness, the computational basis of consciousness, or any other basis of consciousness.
It's an interesting problem to wonder whether or not they are conscious, he mused, but we will helplessly perceive them to be conscious because they will seem that way. You can talk to these companies who make them—it worries me on some level. They will rapidly surpass us, and if we believe they're conscious, they will have all the moral attendant responsibilities and rights. This will further dehumanize us, further dehumanize nature, and make us less relevant because we're building these successors.
Yeah, but for most people this problem will go away, he concluded, because of course, they will believe these robots are conscious—how can you not? You can talk to them. People will have intimate relationships with them already now, right?