David Eagleman, Neuroscientist and Author, on the Brain as a Neural Parliament, AI Hallucinations, and Rethinking Democracy with AI

00:28:48 · Dan TurchinPlay from here

[00:28:48] S2: The next version of this podcast, maybe it will be David and Dan in Taylor Swift Headquarters. Right? Taping signs or knocking on doors or something because that's a... It's it's very astute whoever said that. When we were just getting to each other before starting the recording, we've kind of gone through kind of run a show stuff. I'd sent you a bunch of topics. And you said, had this epiphany. I think I know why we dream. And you recently recorded an amazing conversation with Sam Harris, so you pretended to ask my permission, but I was like, Oh my gosh, yes?

00:29:29 · David EaglemanPlay from here

[00:29:29] S0: Great. Well, we were just talking about talk topics. Yes. Explain. Okay. Great. So about six years ago, I published a book called Livewired, which is about brain plasticity, and one of the things that strikes me so amazing about the brain is that, for example, if you go blind, the other senses take over the visual part of your brain, the visual cortex in the back of your head. And so it's not really the visual cortex. It's just the part of the cortex that happens to be used for vision as long as your eyes are working. And if they're not working, the brain doesn't let any territory lie fallow. It takes it over. Okay. Now the surprise was, to me, in 2013, some of my colleagues at Harvard did a study where they blindfolded people and put them in the brain scanner, and then they would make noises or touch the person on the hand, and and they were looking at the signals. But to their surprise, what they found out is that after about sixty minutes, the visual cortex would start to respond to sound and touch. Now that was mind blowing because how could this takeover start happening after just sixty minutes? And what I realized, my student and I were talking about this, and we realized that because our planet rotates into the darkness for half of the time, your visual system is at a unique disadvantage because in the dark, you can still hear and smell and taste and touch, but you can't see. And, obviously, I'm talking about evolutionary time before we made electric lights. Okay. So, I mean, it was really dark, and you can't see, and that means that that that vision is disadvantaged compared to the other senses. Meaning, all night long, your visual system is at risk of getting taken over. You're essentially blind. I mean, especially when you sleep. There are many hypotheses for why we sleep, but one of them is that it's just to stay out of trouble. You curl up in the corner of a cave, and you shut down and restore energy and stuff like that. Anyway, you know, even when you're asleep, you can feel if something crawls on your skin, you can hear a noise, things like that, but but you can't see. So what we realized was that dreams are the brain's way of defending the visual territory at nighttime.

00:31:39 · David Eagleman, Dan TurchinPlay from here

Every ninety minutes, if you look up the circuitry of dreaming, it's this very ancient circuit that just blasts random activity into the visual cortex and only the visual cortex every 90 minutes. So every 90 minutes, you just slam some random activity in there. And so it's essentially a screensaver dreaming. And and this... So we did, you know, quantitative studies on this. We compared 25 different species of primates, looked at how plastic their brains are, in other words, how how flexible their brains are, and how much dream sleep they get, and it turns out it correlates perfectly, which is to say, like humans, we have very flexible brains, and we do lots of dreaming to defend against this takeover. But other, you know, monkeys like lemurs, they don't... They they have very not plastic brains. Their visual cortex has no danger of getting taken over. They have very little dream sleep. So, anyway, that's... That seems to be why we dream at night. It's to defend the territory from takeover from the other senses. [00:32:39] S2: I didn't realize that the parts of the brain that are being unused, like, by a sense that's disabled, it can be used by another sense. Yeah. So so the whole... We have full capacity of brainpower even if it's not consumed by all the senses, say say equally. It denies

00:32:39 · Dan Turchin, David EaglemanPlay from here

[00:32:39] S2: I didn't realize that the parts of the brain that are being unused, like, by a sense that's disabled, it can be used by another sense. Yeah. So so the whole... We have full capacity of brainpower even if it's not consumed by all the senses, say say equally. It denies [00:33:00] S0: that. Exactly right. Yeah. The cortex, which is the wrinkly outer bit, that's essentially one trick pony. It's the same circuit repeated over and over and over and over the whole way across. And so even though we look at it, we say, oh, that's visual cortex. That's auditory cortex. That's, you know, sensory cortex for for, you know, your body. It just happens to be that based on the wiring that comes in. But if something breaks about that wiring, then it says, oh, that's cool. [00:33:25] S2: I'll use this territory for something else. I've read about studies that you've conducted where people who are deaf, maybe they have like a heightened sense of touch, and so they can learn to quote hear through like haptic feedback. That's exactly right. So what we did is

00:33:25 · Dan Turchin, David EaglemanPlay from here

[00:33:25] S2: I'll use this territory for something else. I've read about studies that you've conducted where people who are deaf, maybe they have like a heightened sense of touch, and so they can learn to quote hear through like haptic feedback. That's exactly right. So what we did is [00:33:40] S0: we made a vest with vibratory motors on it that captures sound, and so for a deaf person, we're capturing sound, breaking it up into frequencies from low to high, and deaf people can learn how to understand the language of that and come to hear the world. We shrunk that down to a wristband. I actually ran a company on this for the last ten years. A wristband with vibratory motors on it, it does the same thing. It's capturing sound, turning into patterns of vibration on the wrist, and deaf people can understand the world that way. Because it doesn't matter how the information gets into the cortex, as long as it gets there, the brain will figure out what to do with it.

00:33:40 · David Eagleman, Dan TurchinPlay from here

[00:33:40] S0: we made a vest with vibratory motors on it that captures sound, and so for a deaf person, we're capturing sound, breaking it up into frequencies from low to high, and deaf people can learn how to understand the language of that and come to hear the world. We shrunk that down to a wristband. I actually ran a company on this for the last ten years. A wristband with vibratory motors on it, it does the same thing. It's capturing sound, turning into patterns of vibration on the wrist, and deaf people can understand the world that way. Because it doesn't matter how the information gets into the cortex, as long as it gets there, the brain will figure out what to do with it. [00:34:14] S2: One of the things that's fascinating to me about brain research, this applies to a lot of areas of technology, but specifically to the brain, is that no matter how much we think we know, as a community, it seems like we're well aware of how much we don't know. So maybe just as a as a thought experiment, I know I gotta get you off the hot seat, and I'm gonna restrict your time, but you gotta answer this one last important question for me. Gladly. When David and Dan are back here and it's 2036 and not 2026, what is something that will be just foundational about our understanding of the brain that today just would seem like science