122 | David Eagleman on Tapping Into the Livewired Brain

Imagine you were locked in a sealed room, with no way to access the outside world but a few screens showing a view of what’s outside. Seems scary and limited, but that’s essentially the situation that our brains find themselves in — locked in our skulls, with only the limited information from a few unreliable sensory modalities to tell them what’s going on inside. Neuroscientist David Eagleman has long been interested in how the brain processes that sensory input, and also how we might train it to learn completely new ways of accessing the outside world, with important ramifications for virtual reality and novel brain/computer interface techniques.

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David Eagleman received his Ph.D. in neuroscience from the Baylor College of Medicine. He is currently the CEO of Neosensory, a company that builds sensory-augmentation devices, as well as an adjunct professor at Stanford. His research has involved time perception, synesthesia, and sensory substitution. He is the founder and director of the Center for Science and Law. He is a bestselling author of both fiction and nonfiction. He was the writer and host of the TV show The Brain with David Eagleman, and writer of the Netflix documentary The Creative Brain. His most recent book is Livewired: The Inside Story of the Ever-Changing Brain.

• Web site
• Stanford web page
• Google Scholar publications
• Neosensory
• Talk on The Livewired Brain
• Amazon author page
• The Brain with David Eagleman (PBS)
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0:00:00 Sean Carroll: Hello, everyone, welcome to the Mindscape podcast. I’m your host, Sean Carroll. Surely, you’ve read these stories in the news media about how one or another thing you could do will change your brain, right? Playing Angry Birds changes your brain. Reading Twitter changes your brain. Eating Captain Crunch changes your brain. It’s very scary, like your brain is very precious to you, all this stuff keeps changing your brain.

0:00:22 SC: Well, it’s all true, of course, but here’s the thing: Every time you open your eyes, it changes your brain. In fact, forget about opening your eyes; every bit of sensory input you get changes your brain, and probably even without sensory input, your brain would be changing because we call it looking and listening and getting memories imprinted, right? The connections between our neurons are slightly being shuffled by the imprints that we get from the world around us, the brain is something that changes, it’s not a static thing.

0:00:54 SC: Today’s guest is David Eagleman, who is a neuroscientist, author and entrepreneur. Dave and I have been friends for a long time, done a lot of things together. He has a new book out called Livewired: The Inside Story of the Ever-Changing Brain. And it’s about exactly this idea that you should rather than think of the brain as a fixed structure where we move around the furniture inside, the brain itself changes. And there’s sort of subtle ways that happens, like when you get a new memory, but there’s also deep and profound ways that it happens, and we can use this plasticity of the brain to our advantage, we can use it for people who are missing sensory apparatuses, people who can’t hear, who can’t see, we can replace those modalities by giving the brain other ways to pick up signals from the outside world, the brain will rewire itself to compensate.

0:01:41 SC: And of course, we have a whole frontier ahead of us in virtual reality, where not only can we seem to visit places that are very different than the reality we live in, but we can be different things. If you’ve ever been in a video game or in Second Life and anytime when you have an avatar, the avatar doesn’t need to look like you, and moreover, the avatar doesn’t even need to be humanoid. Interestingly, the brain will rewire itself just a little bit to take control over whatever kind of shape that thing that is your avatar in virtual reality actually has. This idea is going to become more and more important as we break down the barriers between the brain and the rest of the world through brain-computer interfaces, who knows, neural laces, implants and so forth.

0:02:27 SC: So David is a wonderful person to talk to about this stuff. He’s very engaging, he knows this stuff inside and out, there’s a lot of good stories here. I think this is going to be an episode you really like.

0:02:38 SC: Now, occasional reminder that here on Mindscape, we have a Patreon you can contribute to. Just go to patreon.com/seanmcarroll. The benefits are, number one, you get ad-free versions of every episode of Mindscape; number two, you can ask questions at the monthly Ask Me Anything episode, and number three, and most important, you feel like you are a supporting member of the Mindscape community. I think that’s what everyone wants to be. And so with that, let’s go to David Eagleman on the Mindscape podcast.

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0:03:22 SC: David Eagleman, welcome to the Mindscape podcast.

0:03:22 David Eagleman: Hey, great to be here, Sean.

0:03:23 SC: So the brain, it’s very complicated, I don’t know if you’ve noticed this. As a simple-minded physicist, this is very hard sometimes to get… Wrap my brain around the brain.

0:03:33 DE: Yes, yeah, it’s… As you know, and just to set context here, it’s got 86 billion neurons, neurons are the specialized cell type in the brain, and each one of these is connected to about 10,000 its neighbors, so you’ve got about 0.2 quadrillion connections, and you have changes happening every second of your life at all these connections…

0:03:55 SC: Yeah…

0:03:55 DE: Yeah, and actually, sorry, just that these changes go all the way down to the inside of the cells too, and down to the nucleus and the genome.

0:04:04 SC: Oh, okay, you know, somehow that escaped me, except it was one of the questions I want to ask about what does it mean when we say the brain is changing. I know the strength of different connections between the brain changes, but you’re telling me that the individual neurons change, their nuclei, etcetera.

0:04:22 DE: Yeah. So here’s the interesting thing. AI, which has been tremendously successful, has taken off from essentially a cartoon version of the brain, which is that you have these neurons and connections between them, and so AI says, look, let’s just worry about what are all the units and the strength of the connection. We adjust the strength. But in fact, yeah, everything is changing in the brain, you have all kinds of levels, layers of things changing, from the strength of the synapse to the fact that the neuron itself is like a giant tree that’s unplugging and re-plugging and seeking and moving its branches all the time and looking for new connections, to the number of receptors that it distributes on the surface, to the biochemical cascades on the inside, all the way down to the genome, inside the nucleus, what’s called epigenetics, which is the way that it changes the conformation of the genome so that certain genes are expressing more, and some are getting suppressed, that sort of thing.

0:05:19 SC: I love this because we’re getting wildly off-topic right away, so this is the best kind of… The best kind of podcast. Because you bring up AI, and I’ve talked with a few people in the AI world and will continue to do so, and you just said AI has been tremendously successful. But that depends on what your standards are, right? I mean, especially in deep learning, neural net kind of work, we throw a bunch of data at a system and it picks out some patterns and learns on the basis of that, but when I’ve talked to people in the podcast like Stuart Russell, Melanie Mitchell, a couple of things come through. One is the difficulty in teaching AI systems common sense, and another one is the brain isn’t just big with 86 billion neurons, but it’s structured, right, there are layers and sub-organizational pieces that exist in a hierarchy, and AI doesn’t have anything… Or AI doesn’t quite function the same way in many of its most successful implementations.

0:06:17 SC: So while I have you here on the podcast, do you think that we should be taking more literal lessons from the brain when we think about AI?

0:06:26 DE: Oh, of course, yeah. I mean, AI is so distant, the way I see it is it’s like a fork in the road or a fork in code where you’ve got… AI having gone off in one direction, and when I say tremendously successful, I mean it can do things like distinguish photographs of cats from dogs with super human performance, but it can’t do anything that a three-year-old kid can do, like walk into a room, decide where to go next, navigate a complex set of obstacles, put food in her mouth, manipulate adults, all the things that a kid can do. So it turns out that, yeah, the way that we’ve gone off with AI, can do great things, but it is nothing like the brain, and we have so much more ahead of us in neuroscience that will eventually inspire AI and make it a lot better.

0:07:15 SC: Okay, good. It’s probably both ways, right? We can be hamstrung by thinking too much about the brain when we do AI, and then we can miss chances to take advantage of the things we learn about the brain.

0:07:26 DE: Yeah, well, I think the whole key is figuring out what are the principles that the brain is implementing. There’s obviously tons of detail, but what is actually happening in the brain. Like if you were looking at the nucleus 100 years ago, and you might say, gosh, there are millions of proteins around here, and it’s infinitely complicated, but then Crick and Watson come along and say, hey, it’s about keeping the order of the base pairs and then everything else is detail. That’s the kind of stuff that we need for the brain. And that’s actually what I’ve endeavoured to do in my book, Livewired, is try to figure out what are the principles, what’s happening here with this system that is not anything like hardware or software, but it’s this entirely other thing, which of course I call liveware, which is doing something very different than what we typically do in Silicon Valley.

0:08:21 SC: Yeah, and I think that the great thing about your new book is how much it emphasizes the changeability of the brain. I’m always amused by these stories that say like playing video games changes your brain and you’re like, well, so does opening your eyes change your brain in some ways, so that’s not a very fascinating thing. But before we get there, I want to give you a chance again, once I have you here, because you’ve written other books, and one of the lessons I took from other things you’ve done is that the unimportance of our rational cognitive brain to much of what goes on, right? I mean, the brain is hierarchical, there are layers, there are many little modules going on, and maybe this will be important later on. Tell us a little bit about how our conscious brains are just sort of riding on top of a whole bunch of things going on beneath the surface.

0:09:11 DE: Yeah, the conscious part of you is like a broom closet in the mansion of the brain, and almost everything going on, you don’t have access to, and you don’t even have awareness of, of course. So an analogy that I used in my book, Incognito, I was like, we are… It’s like you are a stowaway on a transatlantic steam ship and you’re taking credit for the whole journey without acknowledging all the machinery under foot. So our brains are up to enormously complicated stuff, just the fact that each one of these neurons is popping off between tens and hundreds of times a second as in sending these little zeros and ones around, and you’ve got these… The unbelievable number of spikes happening in your head in any one second, if each of these translated to a photon of light, it would be blinding to you, but you don’t have access to that.

0:10:07 DE: All you know is, oh, I feel hungry, or whatever the thing is, or it happens when you think, oh, I just had an idea. It wasn’t you that had the idea exactly, it was your brain’s been working on that for days or weeks behind the scenes, evaluating hypotheses, comparing things, trying things out, simulating possible futures, and so on. Eventually it serves up to your conscious mind and you say, oh, I’m a genius, I just thought of something, but we’re sort of the last guy on the ladder to get any information.

0:10:37 SC: Well, I think probably that’s something that we can easily swallow when it comes to the fact that we get through the day so easily. If you drive to work, you often are not even conscious of the decisions you’re making, right, or most people don’t know how to walk if you ask them explicitly how to move their limbs, but it works. But what about when we’re explicitly being conscious? Like if we’re usually using our cognitive capacities to try to be rational, is there… Should we be a little bit more skeptical of our abilities to be rational under those circumstances?

0:11:10 DE: In general, that’s always worthy of skepticism, because we’ve all had the experience of thinking, okay, I’ve thought through this problem, I’ve got it exactly right, I know exactly all of this logically fits, and then you find out at some point, oh, actually, I can’t believe I overlooked that, how did I not see that? So this happens to us all the time, so we shouldn’t take anything too seriously about our own cognition or our belief that something is right. And of course, people end up… For example, with mental illness, people believe that they have the right story about something, and it turns out no one else agrees with them.

0:11:50 DE: Yeah, what’s weird is We’re all trapped on our own planet, essentially. I saw this movie poster for The Martian with Matt Damon and he’s standing all by himself on the red planet, and I thought, wow, that’s just a perfect analogy for what it’s like to be a human. You’ve got this inner cosmos of your brain, you’ve got yours, I’ve got mine, everyone’s got theirs, and we believe everything to be right and self-consistent on our planet, but then of course, especially now, you just, you talk to other people who have different political opinions than you do on social media, and each one of us thinks, wow, I know that I’m right and I’m the default human being, and they must be crazy or aggressive or trolling or whatever, you just can’t believe that anyone has a different opinion than you do.

0:12:39 SC: Well, actually, that’s exactly the metaphor I used to my book, The Big Picture, I called them planets of belief, and different people have different pieces that fit together very nicely on their planets, but they might be very incompatible with someone else.

0:12:52 DE: Awesome, wow, that’s great.

0:12:54 SC: Trying to influence the social psychology literature, let’s see how far I can get there, but… Okay. And this is sort of an entry-way into the fact that the brain is modular, it comes in pieces, and we’re going to get to how it changes and things like that, but I’m worried by the computer metaphor a little bit. I mean, in some sense, we understand computers a lot better than we understand the brain, and I think that it’s very tempting for people to think of their brains like a little laptop computer, but there are ways in which that’s just a bad idea, right?

0:13:28 DE: Exactly right. One thing is the word memory, it turns out that memory is so different in computers than it is in a human brain. In a computer you’re storing a little file of some sort, and that’s an exact replica of what’s happened. But of course, if I tell you a joke, you don’t remember phoneme by phoneme exactly what I said, like an audio recording. Instead, you could turn around and if you speak another language, you can tell it to someone else in another language right away, because it’s the gist of the joke that you’ve gotten. And of course, the gist of it has to do with every one of your experiences leading up to this moment, what that joke means to you on your planet.

0:14:07 DE: Right, that’s one thing, but this is also why I introduce the term liveware to distinguish it from hardware and software, because often people, when they’re talking about the brain, sort of make that mistake of using those terms because we’re so used to them, but of course, here in Silicon Valley an engineer is given kudos for making clean, trim efficient hardware and a software layer that sits on top. But what’s happening in the brain is totally different, because every time activity passes through the brain, it is actually changing the structure, and it’s not just changing the structure, it’s doing so, or at least this is what I propose, a whole framework for thinking about this in the book, it changes it, there are all these different time scales.

0:14:50 DE: So you’ve got certain things in the brain that are changing rapidly, all the way to things that are changing slowly. And this has to do with different areas of the brain and different layers, and the stuff that I mentioned before about synapses, biochemical cascades, all the way down to the changing of the genetic expression. So essentially each layer is looking at the one above it and saying… Sorry, each time layer I’m talking about, is looking at the one above it and saying, look, do I believe the data, is that actually stable enough that I’m going to make a change? Okay, yeah, I believe that, I’m seeing that over and over, I’ll go ahead and make a change and then the next time layer says, okay, well, I’m a little more conservative, so I’m going to wait and see. So there’s things that are changing it all over the brain, all different time scales, all the time.

0:15:37 SC: Good. In physics, we call that through normalization group, so there’s a lot of similarities there. But maybe we can dig into these layers and modularity a bit more, I think that the computer metaphor is not the only one that gets in the way, we also have… When it comes to any living organism, we have the sort of metaphor that the DNA is a blueprint and you just sort of print out what it’s like, but one of the points you make is that the different parts of the brain change their responsibilities in response to various things that are happening. But clearly there’s some structure there in the DNA telling us what to do, telling the different parts of the brain what to do. What is the balance between how much is pre-programmed and how much we pick up along the way?

0:16:25 DE: Yeah, it’s interesting because you and I are both old enough that we remember when the year 2000 came along and the Human Genome project came to fruition, and it was a very exciting time, because it was all going to be written down, all the instructions for putting together a human, including the brain. And as it turns out, it was disappointing in a sense, scientifically speaking, because it really didn’t tell us too much. I mean, it’s super important work, and I’m glad we have it, but the argument I make in the book is that the other half of what wires up your brain will never be written down in a book because it’s everything all around us, it’s all of your experiences, everything that’s happened, every conversation you’ve had, every friend you’ve had, your parents, all that stuff, and more broadly, your culture and your society.

0:17:12 DE: So there’s this old question in biology, of course, about nature versus nurture, and I think it’s pretty much understood at this point that it’s completely a dead question, nature versus nurture, because it’s always both, because these things interact with one another, meaning, you come to the table with a certain genome and these are sort of your starting instructions that start the dominoes kicking over, and then every experience you have from the moment you pop out of the womb is changing the structure of your brain. And that can feed all the way back to your genetic expression, so these things become very tightly intertwined from the get-go.

0:17:51 DE: The way I think about it, I guess the way a physicist would think about it, is sort of like a space-time cone, where you… Given your starting point of the genetics, you can go off on all these different trajectories, but sort of bounded, presumably, by the genetics you come to the table with. For example, I could never be a swimmer like Michael Phelps because I just don’t have the wingspan he has. So you’re bounded somehow by your genetics, but within that there’s a lot of space where you might go, depending on your experiences.

0:18:24 SC: You do have some vivid examples in the book of the importance of this process by which the brain becomes wired dynamically during childhood, because there are unfortunate examples where it didn’t happen, right, where someone was just completely deprived of the ordinary context and stimuli that the rest of us get.

0:18:45 DE: That’s exactly right, yeah. These are some of nature’s tragic experiments where you have a child who’s so badly neglected that… Here’s the way to think about it, is that Mother Nature has figured out this thing with humans, especially, where we are the most plastic species around, and by plastic, I mean flexible, modifiable on the fly. And so what Mother Nature figured is, hey, instead of trying to wire everything up from the get-go, I’m just going to drop this animal in to the world half-baked and let the environment wire this animal up, and that’s turned out to be an unbelievably successful strategy, and we’ve taken over every corner of the planet and invented all kinds of great stuff like podcasts and so on.

0:19:32 DE: But it’s a gamble. It’s a gamble, because what you have to assume is that a child is going to get the right kind of input, and there’s a pretty broad definition of what the right kind of input would be, but at minimum that includes love and touch and language and that kind of stuff. And so occasionally you’ll find these kids who are so severely neglected that they didn’t get the right kind of inputs and their windows of plasticity close, and then they are unable to learn things like language or even how to chew food or how to interact socially. And a couple of the cases I discuss in the book, this poem, are found by, let’s say, the age of 11 or 13, but it is too late for their brain, it’s at a point where it can’t figure out how to do it correctly anymore.

0:20:22 SC: Which is a pretty killer argument against the pure nature idea, right? I mean, the pure nurture idea also doesn’t fly, but you need some upbringing at the right crucial time.

0:20:33 DE: Yes, exactly right. Yeah, and this is, as I said, this strategy of saying, look, let’s just drop into the world half-baked means that we have these extraordinarily long infancies, much longer than any other animal. But boy, it really pays off, because what a kid can do is go and figure out what other humans have learned before him or her, and then springboard off that, as opposed to if you’re a goat, you’re born and you have to learn how to be a goat again, in every generation. They don’t have goat school and goat libraries and so on, goat internet to jump… To jump to the next level.

0:21:17 SC: Goat Wikipedia, yeah. But is there a way to quantify or test this idea that we are the most flexible in some way, it seems plausible to me, but what does it mean?

0:21:28 DE: Yeah, so just as an example, I just published a paper comparing 25 species of primates, and you can look at all kinds of things, like how long does it take before they wean from their mothers, how long before they learn how to walk, how long before they reach adolescence. There are all kinds of measures like this, which at least are good proxies for plasticity, that tell you essentially how much an animal is coming to the table prepared or unprepared, preprogrammed or not, and then at the cellular level, there are all kinds of measures you can take about how flexible the neurons are in the networks of neurons, as opposed to how pre-baked the whole system comes.

0:22:10 SC: And I love the examples you have in the book about where we do have in our brains different parts, different physical locations in the brain that are dedicated to certain purposes, right? Occipital lobe or whatever, auditory cortex, and maybe it’s not a cortex, I don’t know, but if something happens where you go blind or something like that, that part of the brain just doesn’t waste away or die, it gets repurposed, which is kind of amazing.

0:22:40 DE: Yeah, exactly. The main lesson I would say that’s come out of neuroscience on this topic is that no real estate ever sits unused, no land lies fallow. Instead, it gets taken over, so if a child is born blind, the part of the brain that we would normally call the visual cortex is no longer visual, now it’s doing other things, doing hearing and touch, and so on. And if you’re born deaf, your auditory cortex, in quotes, it’s longer auditory cortex, it takes over, it’s taken over by other functions. And one of the things I mention in the book that’s always just stunned me is there’s a type of surgery called a hemispherectomy, which is when a child has really bad epilepsy on one side of their brain. And they go in for this surgery where half of their brain is removed, and it turns out as long as you do it when the kid is young, let’s say before six or seven, the child is just fine.

0:23:35 DE: And the reason is the remaining half just sort of re-wires, taking over any functions that were on the missing half, and it does that, and occasionally you’ll find a child who was only born with one hemisphere, and the way that the rewiring happens is just stunning where the child often, there’ll really be no clues, no cognitive clues that this child only has half of a brain. So yeah, it’s an extraordinarily flexible system and so… Yeah, and what this means, by the way, just as a side note, is that for someone who, let’s say, is blind, they actually provably have better hearing and better touch because they just devote more real estate towards those other functions, and the more you have, the better. Normally a brain is busy sharing the real estate with all these different tasks, but if you’re devoting a lot of it to one thing, you can be quite great at it.

0:24:27 SC: And what’s amazing to me is that obviously there is some genetic predisposition to put different functions in different parts of the brain, like our visual cortex is in the same location in everybody, but it can also be completely rewired under the right circumstances, so clearly there’s some give and take there.

0:24:46 DE: Exactly. Well, the only reason that it’s the same place in everybody is because what you have, what the genetics determine are these very basic instructions about, okay, take these fibers from the eye and plug them into this part of the thalamus called lateral geniculate nucleus, and then from there take neurons and plug those into the back of the head, the occipital cortex. That’s what the instructions give you. Therefore, data from the eyeballs comes in and ends up making its way to the back of the head, and so that becomes what we call visual cortex.

0:25:17 DE: But yeah, in 2000, a group at MIT did an experiment where they took the data from the eyeballs and they rerouted it so that it went to a different part of the brain, in this case, what would have normally been the auditory cortex. This was in ferrets, of course, not humans. And what happened is that part of the brain, what they would have thought of as the auditory cortex, now became visual cortex, it had all the properties of visual cortex, and it behaved like it, the animal could do all kinds of visual tasks with it. And so what this brings home for us is the fact that when you look at the cortex, which is the wrinkly pink outside bit, it’s about 3 millimeters in thickness on the outside of the brain, everywhere you look, it looks the same in terms of, for example, the cellular architecture looks the same. And that’s because it is the same, it’s the same stuff, and it’s just a matter of what data cable you’re plugging into it. If you’re plugging in a visual data cable, then it becomes visual cortex, auditory and so on.

0:26:18 SC: So that was going to be my next question. The actual individual neurons in the auditory cortex are essentially indistinguishable from those in the visual cortex, is that right?

0:26:25 DE: Exactly right. If I showed you, in fact, if I opened up a hole in somebody’s skull, and let’s say had a magical microscope that could look at all the activity and all of the neurons underneath that opening, and I said to you, Sean, what part of the brain are we looking at, is that visual or auditory or somatosensory, you would have no idea. And I would have no idea as a professional neuroscientist, because it’s exactly the same stuff, it’s just spikes, it’s these little electrical signals, and then you have these chemical signals to carry information from one neuron to the other. It looks exactly the same everywhere, no matter where in the cortex you look.

0:27:00 SC: And not having half a brain is obviously a dramatic example of this, but maybe more, not more provocatively, but more usefully, when people lose limbs or something like that, or when people gain extra sensory things, they can rewire the brain, or the brain rewires itself, I suppose, is a better way to say it, to adapt to that new kind of body that they have.

0:27:25 DE: Yeah, exactly. One of the stories I tell in the book is just that in the 1960s, a neuroscientist named Wilder Penfield was the first to discover that if you stick recording electrodes into the brain, you find that there’s a map of the body in the brain, so it’s as though your brain knows that you have arms and fingers and legs and toes. And everyone thought, wow, this is amazing, it must be genetically pre-specified. But it turns out it is not, because if you, for example, lose an arm, your map of your body and your brain will change so that it represents a body that does not have an arm. And so what this tells us is that it’s activity-dependent, and depending on the information streaming up into the brain, the brain changes its map of what’s going on.

0:28:13 DE: The thing to remember, of course, as an introductory way of thinking about this, is that your brain is locked in silence and darkness, it’s just this three-pound mission control center, it has no idea what your body is supposed to look like.

0:28:27 SC: There’s no xyloscopes in there, yeah.

0:28:27 DE: One of the stories I tell, ’cause I just love this so much, is there’s this dog named Faith, who is born without front legs, and so Faith just walks bipedally on her back legs and it’s stunning to watch her. And the question is, could any dog walk on their back legs? Probably, but they don’t have the sufficient motivation to do it, but she had to get to food and water and her mother and so on, so she just walks on her back legs. But the point is you look at Faith and it’s clear that the dog brain is not pre-programmed to drive the dog body, brains are just programmed to figure out what are their capabilities, to figure out what are the affordances that they have in the world, and then adjust accordingly so that it can drive the machinery.

0:29:15 SC: And clearly we have some experience with losing limbs and adjusting appropriately, but increasingly we’re gaining limbs back, right, I mean, that we’re getting prosthetic limbs, and can the brain rewire itself to think of a prosthetic limb as part of our body?

0:29:32 DE: Oh, exactly, and it turns out that you can do things like for somebody who’s totally paralyzed, you can put an electrode array in their motor cortex and then hook that up and have them control a robotic arm, and this is of course very useful for somebody whose body is paralyzed. The engineers have to make a lot of tweaks to try to make their algorithm better, but really most of the work is just for the person themselves to learn flexibly how to think about it, to move the arm. How to think just right, to make the fingers move subtly and grasp this and so on. And in monkeys there are experiments where the monkey can use, let’s say, both his arms and a third robotic arm, and they can function just fine that way.

0:30:18 DE: And of course, these are the expensive ways of doing it, but the cheap way of doing it is with VR, where you can hook up a VR game, where let’s say you’re controlling a third arm. So one of my colleagues here at Stanford, Jeremy Balenson, has this game where you’re holding two controllers, you are with those controlling your two arms in virtual reality, and then you’re also, you also have a third arm coming out of your chest, and by turning the controllers, by turning your wrists, you’re controlling the third arm. And what you’re trying to do is grab as many boxes as possible in as short a time, and so it turns out the way to do this is to use the third arm, and it only takes about three minutes for people to get really good at it.

0:31:01 DE: And of course, there’s a sense in which we know how flexible our body plan is, because when you jump on a bicycle, evolution never saw wheels come in, but it’s not that hard for you to figure out how to use it, or a pogo stick or a hang-glider or anything like that, you are… That becomes part of your body.

0:31:21 SC: I’ve heard the famous story of the virtual reality lobster that I guess Jaron Lanier did, where some people, at least some people sometimes can learn to control all eight legs of a lobster in virtual reality independently.

0:31:34 DE: Yeah, exactly. You know, it’s funny, I tried looking that up and I couldn’t find any detailed information on that, so I just mentioned it as this story that inspired other VR guys to try quantifying this.

0:31:45 SC: Well, but in a case like that, can you actually see changes in the brain, does the little homunculus, does the map of our body and our brains become different if we lose a limb or for in VR?

0:32:01 DE: So to my knowledge, no one has combined this VR with FMRI, with brain imaging, but it has to be true. It just has to be true. But in the same way that they’re changed in your brain when you learn how to ride a bicycle or… One of the things I mention in the book is this guy, Destin Sandlin, who got from his friend a backwards bicycle, so when you turn the handlebar to the left, it turns the wheel to the right and vice versa, and so it took him a month to get good at it, but then he’s able to ride a backwards bicycle and he can jump on different bikes and ride them both. Of course, there are changes in the brain. To my knowledge, no one’s done FMRI on him with those bikes, but that’s how everything is stored, is by changes in the structure of the brain.

0:32:50 SC: I guess that makes sense, but it highlights a question I hadn’t even realized that I had, which is seemingly there are changes in the brain and then there are changes in the brain, right? Maybe this is a remnant of the bad computer metaphor, where we think of the computer as having certain hardwired things and then we have software that we can download and so forth, so no one is surprised that I can learn to do things. That’s fine, and in some weak sense, that’s a change in the brain, but is that all there is or is there a stronger sense of the image that I have of myself in my brain is literally different?

0:33:28 DE: It’s interesting that your intuition is to think of it in a weak sense, in a strong sense, because that’s all anything is. I mean, it’s all just changing the brain. So when you… Sean, I can’t remember how long ago you and I met, probably at least a decade ago, but when you met me and learned that my name was David and what my face looked like, that is represented by changes in your brain, that is synchronized over literally millions or hundreds of millions of synapses, the connections between neurons, and all the way down to biochemical cascades and receptors and so on. And of course, I could never know how exactly I am represented in your brain in detail, but I’m represented in the context of other people you’ve met, and maybe I looked a little bit like your friend from the eighth grade, and a little bit of this thing.

0:34:19 DE: And whatever the details are, it orchestrated massive changes in the structure of your brain, and that’s what it means to remember anything, any fact, even the fact that we were meeting online today at 3:30, you have to store that, you have to… Yeah, everything is about changes at the synaptic level, at the biochemical cascade level, sometimes all the way down to the genes.

0:34:46 SC: Okay, this goes back to the conversation we started with, with the neurons firing. I still want to say there’s a structure in the brain, in the sense that certain neurons fire when the action potentials do the right thing, when they’re getting the right input, but then there’s also physical connections between the neurons, right? I mean, are both of those changing in different ways, or is that all kind of the same mush going on.

0:35:13 DE: It’s the same mush going on. What’s often thought about it, I would say all the attention is on the connection, the synapses between neurons, because what we know is that those can get stronger or weaker when we do particular experimental manipulations, we can see, oh, look, that’s gotten stronger, that’s gotten weaker. But I just want to re-emphasize this thing that it’s not only that, it’s that the shape of the neuron itself is changing. What’s happening just past the synapse with the number of receptors that are there to capture the neurotransmitter, the chemicals that are released, that changes the distribution of those receptors, the number of receptors, the biochemical cascades that those lead to, all the way down to the nucleus of the cell, all of that’s changing at once.

0:36:01 SC: Right. But I’m going to just stubbornly try to… It sounds like I’m being stubborn disagreeing with you. What I’m actually trying to do is sweep out all of my misconceptions here. There’s a sense in which I learn something at a surface level, like I’m told, you know, how to read music, and if I sit there and think about it, I can see a different note on the staff corresponds to a certain pitch, etcetera, but then if I do it enough, it becomes automatic and it’s certain… I’ve learned it at a certain deeper level. Is there once again a physical structural difference between those two kinds of learning or is everything just a combination of all these things going on at once?

0:36:40 DE: Well, no, I mean, there are structural differences. So first, if I tell you something that you’re just holding in working memory, let’s say not something like reading music, but I just tell you some translation in Chinese, some word. And so I tell that spider is zhīzhū, so you can sort of remember that and hold in working memory, but it’s not really going any deeper than that, and that’s just the activity in your brain. But for it to actually get cemented into the structure, there are various things you can do to practice that, maybe say it out loud, maybe tell someone else that’s what the word is and so on.

0:37:14 DE: But this goes back… There’s actually two things this goes back to, one is this issue that we mentioned before about the different time scales of change. So something that you hear once and maybe learning the word for spider in Chinese means absolutely nothing to you, and so it doesn’t really have relevance, so it doesn’t ever stick at the deeper levels. By deeper, I mean more conservative, the renormalization group issue. So there’s that. The second thing I want to mention, there’s actually several points, the second thing I want to mention is that when you’re learning something like sheet music, it starts off as a purely conscious issue, think riding a bike.

0:37:55 DE: When you first tried that as a child, it was all about, oh, I’m having to pay so much attention to this, and I’m like, how do I turn my torso and blah blah blah, but eventually it becomes completely unconscious to you, and that’s because you’re actually burning it down into the circuitry. So if you look at the activity in the brain of somebody just starting to learn a bike versus the activity of a professional bicyclist, you see that the latter case, there’s almost no activity in the brain, why? Because it’s been burnt into the part of the circuitry for speed and efficiency. And so in the first case, it’s all conscious and you’re having to think through all the possibilities, and in the second case it’s just really deep into the circuitry.

0:38:36 SC: That’s interesting, the fact that there is less activity in the brain, when an expert is doing something than when a novice is doing something.

0:38:44 DE: Yeah, it’s very counterintuitive. But the first experiments on this were done with the video game Tetris, where it was amateurs versus professionals, and the professionals’ brain isn’t doing much of anything and… Yeah, and it’s counterintuitive in a sense, but it’s because the whole reason the brain is changing is for the purpose of speed and efficiency. So if you can turn something into the physical structure of the circuitry, boy, that makes it really fast and efficient. Let me say just one more thing. The third thing I want to say about change in the brain is that this is also, one can’t ignore the issue of relevance to the organism. So if I tell you some, whatever, some word in Chinese that just really doesn’t mean anything to you, and you couldn’t care less, you don’t have the right cocktail of neurotransmitters present to make any change. But if I tell you something that’s really, really important to you in your career and your survival or whatever it is, that’s really going to stick, because the right neurotransmitters are there that says, wow, this is a piece of information I need that matters for me.

0:39:53 SC: And I guess that’s one aspect of something you already mentioned I didn’t want to quite let go, which is that even when you are… When two people are learning something, the same thing, it’s a different thing happening in each of their brains. Like you said, when I see a new person and I recognize them, I recognize them by relating them to other things in my brain, which means that the fantasy and the matrix of just downloading how to fly a helicopter or how to do kung fu isn’t how it’s going to work.

0:40:22 DE: Exactly right, because the way that you would fly a B212 helicopter and the way that I would is different. So you might think of it in terms of, oh, yeah, it’s just like a motorcycle, I lean it this way and that. I might think of it in terms of, oh, it’s like a horse, when I’m on a horse and I pull this way and pull that way. Of course, I’m not even talking consciously, I’m talking about all the stuff about how it is getting encoded in the brain, exactly. So I mentioned that, I mention in the book that this thing about the Matrix isn’t plausible that you could just download something in somebody’s brain, but there is, I think, a way that we can think about that, which is you’d have to do a very thorough system identification first, which is to say, if I could actually understand your brain and everything about the way it’s working, then maybe I could download the instructions for how to fly that helicopter, but I’d have to really do a lot of work to understand your brain first.

0:41:18 SC: Wouldn’t I have to be you? In some sense, my way of knowing how to fly helicopter is different than your way of knowing it?

0:41:27 DE: Totally, there are different ways, but if I can do system identification on you, I mean, this is pure fancy, but maybe in thousand years we’ll have this, where essentially I present to your brain 500,000 different scenarios, ba-ba-ba-ba-ba, I present this and I’m looking at the activity in your brain in response to each, enough that I have a pretty good sense of what your brain as an individual brain is up to, and then I say, okay, so here’s how I’d add helicopter flying on top of that.

0:41:55 SC: Mmm. Maybe. I mean, people want to do that, right, people want to upload their brains, and I’m always… I’m not skeptical about this at a philosophical level because I’m a substrate independence of consciousness kind of guy, like it’s all just physical particles representing information in motion, but I think that people still are beholden to this metaphor that the information in their brain is like a big file on a computer that they can use a USB connection to just download and run it on some other hardware and it will work perfectly well, but it’s more complex than that, not only within the brain and the neurons talking to each other, but with all of the sensory input and motor output that is involved.

0:42:38 DE: Yeah, and that’s interesting, because in theory, if we could replicate all of the important pieces and parts, which is probably almost certainly much more than just the neurons and their connections, which is how AI folks think about it nowadays, but if you could actually replicate all the important stuff, and of course, we don’t know exactly which details are the important parts. But if you’re a substrate independent guy, then you should be able to upload your brain. You have all this stuff about your body and of course all the organs in your body, like your adrenal gland and all these other things that are sending hormones and information to your brain, but all that stuff can be summarized pretty easily, like in a 1 MB file probably, and so the brain itself, those three pounds, that’s the densest representation of you, and then it’s just trying to figure out what are its capabilities in the world, and when it puts information out, what does it get back and so on.

0:43:38 DE: But I suspect it just… I mean, look, we’ll both be dead before either of us can hold each other to a bet that we make on this, but I don’t know, I really don’t think it’s more than 75 years or something before we’ve got essentially uploading, where we say, okay, here’s all the important pieces and parts that we need to capture for you and now you’re in the Matrix.

0:44:02 SC: The secret nightmare scenario is we have… I like the idea that it’s just a 1 MB file that is keeping all of our simple chemical influences that are affecting our brain. So for instance, we become hungry, we become tired, and maybe this is crucially important to how we function in the real world, but maybe it’s not a lot of information, maybe that’s the easy part to put up into the Matrix, but then once we’re there, we go, oh, you know what, now I can control everything, now I’m just going to change the dial so I don’t get hungry, so I don’t get tired. And then we realize that there’s no reason to keep living because we’ve got rid of all of our motivations and we realize that life was all just a weird thing that we were going through and then we turn everything off.

0:44:44 DE: No, I certainly, I certainly agree. I mean, you can’t enjoy the good moments without the contrast of the bad moments.

0:44:54 SC: It’s tricky, yeah.

0:44:55 DE: So yeah, what you’d want to do is have somebody, have a company upload you, but you don’t get control of the dashboard.

0:45:01 SC: Oh, yeah, no, I don’t want that at all. Are you kidding me? I don’t want anyone else to have control over my dashboard. So that’s the dilemma that I’m in. But anyway, like you said, further out than each of our individual lifespans, unless they cure immortality first, that’s always possible.

0:45:19 DE: Yes, let’s hope.

0:45:21 SC: There’s something else you mentioned that I don’t want to quite get let go, which is the monkey with the third arm. Given everything you’ve already said, sure, I can believe that the brain is flexible enough to adapt to a circumstance where I have not just replaced limbs and things like that, but I have new ones, so like I’m a different kind of cyborg being. But there still needs to be some way, now we’re in the real world, not in fantasy world, there needs to be some way for me to get the neural impulses to these extra limbs. Do people think about this in a realistic way about how to actually give ourselves capabilities we don’t already have and wire it successfully to the brain?

0:46:04 DE: Yeah, exactly. So when it comes to motor output, the way they do this with the monkey is they just put an electrode, an array of electrodes, into the motor cortex, and what all these systems are very good at in the brain is flexibility. So they say, oh, okay, look, this part here is controlling one arm, this part’s controlling another arm… Oh, but I see, I have a third arm. So that’s cool, I’ll just share some of this real estate, some of what these neurons are doing, so that now they’re controlling this arm. And of course, the monkey can see what the robotic arm is doing, and so that’s the input, so you’ve got the output of what’s getting caused in the input, and essentially what you have is motor babbling, which is where the monkey tries things and see what’s going on and eventually gets better and better at it, just the way that a baby babbles with language and compares that to what their mother and father are saying, and they get better and better at articulating.

0:46:58 DE: And so when it comes to motor output, yeah, it’s easy enough, you just hook up something and you get the feedback. And then of course, what I’ve been working on for the last decade is what would it be like to add new senses. Could we add a new sense? So we’ve got our eyes and our ears and our nose and mouth and so on, and we’re used to these things and we think of them as fundamental, but in fact, it’s just what we happen to have inherited from a long road of evolution, and your eyes are just turning photons into electrochemical spikes, your ears are turning air compression waves into electrochemical spikes, your nose is turning mixtures of molecules into spikes and so on.

0:47:38 DE: And it’s all the same currency on the inside, and so this got me thinking hard, yeah, starting about 10 years ago, about whether we could just add a new sense. And of course, it’s very difficult to imagine what a new sense would feel like or look like. It’s as difficult as trying to imagine a new color, you just can’t do it. But… So what we did in my lab is we built a… I know you know this, Sean, but we built a vest with vibratory motors all over it, and we can feed in any kind of new data stream and people can come to understand that.

0:48:16 DE: So just as a quick example, and what we’ve done, by the way, is shrunk this down to a wrist band, we’ve actually spun a company out of my lab called Neosensory, and we have this wristband called Buzz, and it’s got these vibratory motors on it, and so for people who are deaf, for example, we capture sound in real time and turn it into patterns of vibration on the skin with this little wrist band, and they can come to hear the world, they come to understand what is happening in the auditory world, just based on the vibration on their skin, because it turns out it doesn’t matter how the information gets to the brain. As long as it gets there, the brain figures out what to do with it and how to use it.

0:48:54 SC: Well, that’s… Yeah, this is a crucial thing, and maybe I’ll just ask you to say the same thing over again, but in different words, because it’s so important, I think, to the future of this, that forgetting about new senses for the moment, but even with the senses we have, we can learn to sense them in different ways. So this seems to me to open up great vistas of opportunity for people who have lost one or another senses.

0:49:21 DE: That’s exactly right. And so… Just as one other example of what we’re doing for people who have lost a leg and they get a prosthetic limb, it’s actually very difficult to learn how to walk with a prosthetic limb, ’cause you have to look at it to see where it is, where it’s swinging, when it’s setting down and so on, because you don’t have any feedback from it. So we put pressure and angle sensors in it and then give that information through the wrist band, and people can come to walk that way again because they’re getting the information, it’s not coming from the leg, it’s now coming through the wrist, but it doesn’t matter. The brain says, oh, I got it, these are correlated.

0:49:57 DE: That’s what the brain is really good at doing is figuring out correlations between things, between, for example, what it’s seeing and what it’s feeling. Yeah, we’ve done this with blindness, so people who are blind, we did this with the vest, and we did this over at Google’s offices where they have LiDAR set up, and so they know the location of everything in the office, so we just brought in blind participants and fed them that data stream, turned into patterns on vibration on their skin, so they could tell, oh, there’s someone off to my left and they’re coming closer and closer, ’cause the vibration is getting more intense. Oh, now the person has changed direction and now they’re going behind me and I can feel them all the way around behind me and so on.

0:50:38 DE: And in a sense, this is better than the vision we come to the table with, because you can’t see behind you and you can’t know exactly when I… You know, it’s like being a Jedi or something and knowing when someone’s approaching you from behind. So yeah, these are ways of putting in auditory or somatosensory or visual information into somebody through a different channel, and the brain has no problem figuring that out.

0:51:01 SC: I think this is what sounds so remarkable, because just like in the VR example where we could imagine having multiple limbs and moving them around, for the replacing vision or sound or whatever examples, we have a mental image for what that would look like, but some of the constraints that are there in the typical biological circumstances need not be there anymore. So it’s kind of hard to visualize, if you will, what it would be like to see 360 degrees all around us.

0:51:33 DE: Right, exactly. So actually in Livewired, I take a few pages just to discuss this issue about how impossible it is to understand someone else’s internal experience. So for example, if you’ve ever had a friend who is born blind, you can try to explain vision to her all day long, but she’s never going to get it, it just doesn’t make any sense. Or if you have a friend who’s color blind and you try to explain the color green to that person, they cannot possibly understand. And the same thing applies here, which is that if you create a new sense, like infrared vision or feeling the invisible states of your body, like your microbiome and your blood pressure and so on, or feeling the stock market or Twitter or whatever you’re doing, it’s totally impossible for someone who hasn’t experienced it to understand what it feels like, ’cause it’s not like touch or taste or hearing or smell, it’s something else, it’s something else that you’re experiencing.

0:52:31 SC: You’re getting dangerously close to the discourse around Mary, the color scientist, right. You know this one?

0:52:38 DE: I do, yeah.

0:52:41 SC: Do you think there are implications of this? I mean, we can actually basically do the experiment. For those who don’t know it, I talked about this with Philip Goff and with David Chalmers, the idea of a scientist who was completely prevented from seeing color, and the question is when she sees color for the first time, does she learn anything new, given that even though she couldn’t see color herself, she was a scientist who understood color at the physical level. And this is supposed to be an argument in favor of, there is more to life than just the physical structure of the brain. And I don’t think many people believe this argument, but maybe this new way of thinking about things changes it somehow.

0:53:17 DE: Yeah, that’s interesting. I think what everybody does get about the argument, though, is that knowing everything about it wouldn’t be the same as experiencing the color orange. In the same way that if I explain to you everything, all the biochemical mechanisms of why chocolate ice cream, what chocolate cream does, it’s a molecule of a certain shape, and a bunch of receptors and blah blah, it has actually no influence on your experience or enjoyment of chocolate ice cream. It makes it no better or worse, because…

0:53:47 SC: Well, the argument’s supposed to be that therefore, there is some kind of knowledge called what it is like to experience something, that does not get reduced to the firing of neurons in your brain.

0:54:00 DE: Yeah, it seems like it’s an emergent property, qualia is. Qualia is the internal experience of something. And we can talk about it in the same way that… Right, I can explain to you all about transistors and electricity running through these and resistors and so on, but that doesn’t tell you why you find this particular YouTube video funny. Yeah, there’s something that’s missing that you need at this higher level.

0:54:27 SC: So what are the new senses that we should look forward to downloading from your website some day, like we can fix the senses we already have, but clearly other wavelengths in the electromagnetic spectra would be good, but is there a completely new sense that we could imagine?

0:54:46 DE: Yeah, yeah, right, so we just had… So we’ve been working on… We’ve got probably 20 different projects of different senses underway, but we just had a developer contest and we had 70 entries to that, which was great, from all around the world where people said, look, I’m going to use the Buzz and build this kind of sense or that. So we had things from, let’s say, different ways of doing navigation directions, which is super cool, but to things like how do you detect COVID risk by looking at the CO2 level and understanding what the ventilation is in a room that way and understanding therefore what your risk of having COVID kicking around in a little room like that is, to things like detecting electrical fields, just walking around and being able to feel electrical fields, the electromagnetic bubble around adapters and stuff like that, to a…

0:55:41 SC: A magnetic field would help you with a sense of direction, right? A compass built in.

0:55:49 DE: That’s right, that’s right. And in fact, in fact some colleagues of mine did that some years ago, this belt that just buzzes in the direction of magnetic north, and so people would wear this and they were always oriented to where north was. And there are a couple of interesting things that came out of this. One is that people wore it for a few weeks and then when they took it off, they retained a better sense of where north was. And I’m very interested in these kinds of things because what that implies is that we already have a little bit of magneto reception, like many other animals who do have it, humans probably have a little bit of it, but it needs of this confirming external signal to really boost that up and make you be able to read that signal.

0:56:35 DE: So anyway, that was the one thing is that people remained much better at it after they took it off. But the other thing that came out of this paper that was written about it was that people would try to explain what it was like to know where north was. And they were trying to explain this to the people who wrote the paper and they didn’t quite always get it, but the different participants could talk with each other and get it really well. And so this comes back to this issue that you need to experience something in order to have a shared language around it and say, yeah, it isn’t it just like that.

0:57:08 SC: Even though there was no special purpose vocabulary for that sensory modality, they were able to come up with ways of expressing what they felt to each other.

0:57:17 DE: Exactly right. And yeah, and this is so interesting to me about what language is and what vocabulary is, it’s all about just shared concepts, or at least concepts that you think are shared. I just assume that you see red the way I see red, maybe we do not, but if we use that word, we can transact and negotiate in the outside world, so… Yeah, but it just becomes weirder when it’s something that’s even more rare and you have to invent a new kind of word for it.

0:57:45 SC: And you mentioned glucose, which brings up something probably people don’t even think about, or at least it’s not the first thing that comes to mind when you ask about new sensory modalities, which is interior sensing. Like keeping track of the various levels of our blood sugar, blood pressure or whatever, is something that is probably easier than various other things we could try to imagine.

0:58:07 DE: Yeah, exactly right. And all you need is whatever kind of sensors already exist, and of course, people are building these things at a blinding pace, and then we just… We take that data and feed it into the wrist band, so you feel this as these spatial temporal patterns of vibration… Yeah, exactly, and the question is, what is that like when you can have a deeper window into yourself, whether… So we’ve done this, for example, with EEG, where you’re wearing one of these portable headsets and you are feeling your alpha waves or your gamma or your delta, you’re feeling what’s going on with you. But yeah, as we get more and more sophisticated with this stuff…

0:58:46 DE: By the way, actually, I’ll mention something interesting. We’ve done this with smart watches where you can feel things like your heart rate, your heart rate variability, your galvanic skin response, which is a measure of your stress and stuff like that. So all of these things you can feel from what the watch is measuring, but what we did then is, let’s say we switch the bands, so I am feeling your physiology and you’re feeling mine, and the question is, what is that experience like when you’re really tapped into what someone else is feeling.

0:59:18 DE: And so our first shot at this was to do this with spouses just to see what is that like? Let’s say you’re traveling across the nation and your wife calls you and says, wow, Sean, you feel really stressed out, are you doing okay, and so on. So we don’t yet know whether this is an aid or a hindrance to marriage, but it’s something that we’re just interested in, about what if you can not only be tapped in to your own body, but someone else’s.

0:59:42 SC: Some things people were not meant to know, David. I’m not quite sure if this a road you want to walk down but… Okay, and we can sort of imagine the vistas here of possibility, but what I like about it is that everything you described so far is pretty realistic on a reasonable time scale. These are things that are happening and the technology is changing rapidly.

1:00:07 DE: Yeah, exactly. I mean, everything that I’ve described so far is not what’s going to happen in a few years, but it’s what we’ve already done in the lab.

1:00:14 SC: Yeah, okay, so now we’re near the end of the podcast, so let’s let our hair down and imagine what will happen as time goes on. We know that Elon Musk has a company, Neuralink, that is aiming toward sort of Iain Banks-esque neural lakes. And I’m sure there’s a long time to go before we have something like that, but what are the prospects for putting… Well, whether it’s through implants or anything else, directly reading what is going on in our brain and sharing that data back and forth across the rest of the world?

1:00:48 DE: Yeah. I mean, that’s clearly where things are going, it’s going to be actually a long while before we get there. We are still in 2020 stuck with FMRI, Functional Magnetic Residence Imaging, it’s our best way of imaging the brain, and the fact is it’s a really crude technology. It’s not so great, it’s slow, it’s got poor spatial resolution, but it’s the best we’ve got. So what Musk is doing, by the way, is in a sense no different from what we have been doing for a long time, which is tipping electrodes into the brain. What he’s doing is making that a much tighter, nicer process where you’re essentially sowing a little string of electrodes into the brain and avoiding blood vessels and so on, so he’s making it better and it’ll be wireless.

1:01:30 DE: But that said, where I can see this is going to really pay off in the world of neurosciences is in clinical neuroscience, so people with Parkinson’s or epilepsy or various other disorders, depression, other things, this might make sense for them to get these electrodes in their brain that not only read but can also write what’s happening with the neural activity. But part of the sort of idea, the mythology about Neuralink is, hey, everyone will get this so we can interface with our cell phones faster or something like that, but the fact is, no one’s going to go in for an open head surgery just so you can text faster than your son can go.

1:02:08 DE: So it’s going to be a long, long time, possibly until after we’re dead, before people are actually doing this. But I will say this is the direction neuroscience has been going, is how do we get finer and finer resolution on being able to read and write. I have a suspicion that in 30 years, we’ll look back at an idea like Neuralink and think, okay, it wasn’t actually the right approach, because I have a suspicion that we’ll be able to do things from the inside, as in we do molecularly precise three-dimensional printing at the atomic level, we build nano robots, you can fit 100 billion of these in a little capsule, you swallow the capsule, they swim around in your bloodstream, impregnate all the neurons in your head, and then they send out signals and you can use a mesh network that would allow these to… All their signals to get compiled on a little helmet on the outside, and you might be able to read everything going on in the brain that way without ever having to open the armored bunker plating of the skull.

1:03:13 SC: Well, okay, I think we need to expound on this a little bit more, ’cause that is exactly what I was wondering. Yes, I agree with you that most people… Maybe Black Mirror episodes are a different thing, but most people will be reluctant to let people take a drill to their skull to put something inside. But is that really the obstacle here, or can we get around that in clever ways? Or are there other obstacles with just reading the synapses at all, like do we have some sense of what the biggest barriers are to overcoming that gap between the brain and the outside world?

1:03:50 DE: I mean, the list of barriers is enormous, but the very first thing would be just understanding the spiking code of the 86 million neurons. We don’t actually even know what subset you would need to measure to get a pretty good picture of what’s going on. So let’s just imagine you have to measure from all 86 billion, that’s challenge number one. So if you had a little nano robot in each neuron in your head that’s sending out signals saying, oh, you just spiked, you just spiked, that’s a good start. But the synapses, what’s going on at the connections between these, which is 10,000 times more synapses than neurons, knowing what’s going on there might end up being very useful.

1:04:29 DE: But on top of that, it’s not just the wiring diagram. I mentioned earlier that the shapes of neurons are changing all the time, and the degree to which a neuron is ready to pop off versus really hard to make pop-off and so on. All of these things, all the way down to this other thing I mentioned, which is the epigenome and how you change the conformation of the chromosomes so that certain genes are expressing more than others. You might actually need all that information and we don’t know, we don’t know the answer to which of that is, oh, that you could skip that and still get a pretty good read of the brain.

1:05:05 DE: But it is possible that even though we’re looking at neurons mostly, we’re only doing that because that’s all our technology can give us, so we’re like the drunk looking for our keys under this street light, just ’cause that’s the only place we can see, but it might be much worse than that.

1:05:20 SC: Is the other direction of information flow easier, is it easier to send information to the brain than to get it out? Like if I just wanted to read Wikipedia without touching anything, just by the power of my mind, is that something that is more realistic?

1:05:35 DE: Well, in a sense, that’s what your terrific eyeballs are doing, you’re looking at Wikipedia, you’re translating all these symbols on the fly and getting an enormous amount of information in your brain that way, so I don’t know that you actually need to do much more than that for Wikipedia. What we’re doing at Neosensory is passing information streams just by this wearable on your wrist, and that’s a super useful way to pass information in and, yes, much simpler. So as far as getting information in there goes, I’ve put all my chips on doing inexpensive, non-invasive ways of streaming information to the brain. Getting it out is the hard part.

1:06:11 SC: I see, okay, very good. Well, well, I presume that there’s uncountable number of projects going on both in laboratories, in academia and in startups, etcetera, trying to do all sorts of these things, because at least it seems like there’s both a utopian far-off goal of everyone having telepathy and being able to record all of their memories in RAM or something like that, but also little steps along the way that are individually useful.

1:06:44 DE: Yeah, I think so. I actually am not sure that anybody views it as the utopian goal, though, to be able to read and write everything and have your memories on a stick, because there’s some sense in which what’s going on in the skull is an inner sanctum that most people probably feel should be private, because you have so many thoughts floating around in your brain and the way that interacts with this higher level of our social lives, they don’t always go together, right? You have thoughts that move through your head that you would never want other people to be able to read or know that you thought something, so…

1:07:23 SC: And yet there is social media and Instagram. Maybe the new generation is perfectly happy with everyone knowing all of their thoughts.

1:07:34 DE: You know what? I doubt it. But that’s very interesting, I should interview some young kids who spend their lives on Twitter to ask, but even still on Twitter, of course, they’re carefully crafting and rewriting and deleting their tweets that are meant to look spontaneous. And it’s true that this just represents this thing, that we’re trying to look a certain way for people. And I don’t think that anybody I would interview, but I’m happy to be proven wrong, but I don’t think anybody would actually say, yep, open up the whole thing, I’m an open book, just read the thoughts flitting through my head. So I suspect that what we’re going to get is better and better, really wonderful clinical tools to be able to help people with all kinds of disorders. But when it comes to things like actual mind-reading, that’s probably going to face real ethical barriers for as long as I can imagine.

1:08:27 SC: I think if you asked people 50 years ago whether there’d be TV shows that basically just put a bunch of cameras in someone’s house and broadcast it, they would be aghast at this terrible invasion of privacy, and yet there’s a lot of such TV shows these days.

1:08:42 DE: Yeah, absolutely. And anybody, anybody with any brains doesn’t make guesses about what the future is going to look like, ’cause it’s so hard to see where these things go. But all I can tell you is the society that I know now is just not going to be up for that, so it’s going to have to be a real shift.

1:09:05 SC: Well, we’re nearing the end of the podcast, and I don’t want to let you get away without explaining to the audience what it was that first let me be aware of your work, because this was 10 years ago when I was organizing a conference on time and the nature of time, and I wrote this book From Eternity to Here, and of course, one of your… In my mind anyway, one of your most famous experiments has to do with how we perceive time in situations of great anxiety or excitement and so forth, and probably there are people here who don’t know about that experiment, so maybe could you explain that to us? And I don’t know whether or not it links into what we’ve been already talking about.

1:09:44 DE: Yeah, I mean, that experiment was just… I was fascinated by this issue of whether time slows down when you’re in fear for your life. When I was a kid, I fell off of a roof and it seemed to take a long time to hit the ground, but once I got to high school physics, I found that it took something like 0.6 seconds and I couldn’t understand how it seemed to take such a long time. And then as I grew up and I became a neuroscientist, I collected all kinds of stories from people who had been in car accidents and things like that, and they described the scene as though it were in slow motion.

1:10:16 DE: So what was interesting to me is there did not exist anything in the literature, there was no study on whether this was true or not and what that would mean to sort of see at a faster rate, take in all this information at a faster rate, or on the other hand, maybe you just lay down memories more densely and you think it took a longer time. So anyway, I did the only experiment, which to my knowledge, is still the only experiment that’s ever been done on this, which is, I dropped people from 150-foot tall tower in free fall going backwards and they’re caught in a net below going 70 miles an hour, and it’s absolutely terrifying.

1:10:51 DE: I did it myself three times, and it’s just so scary falling backwards and you’re eventually caught in the net. What I did is I built this device that flashed information at people at a certain rate so that I could see whether during the fall they were able to take in information faster, in other words, was their frame rate actually different where they were seeing the world in slow motion. Skipping some of the technical details here, if anyone’s interested, you could look up our papers on this, but what we found as far as [1:11:23] ____ time goes, is that people thought the event took a much longer time than it did, and yet nobody was actually able to see in slow motion, as in literally see like Neo in the Matrix.

1:11:35 DE: Instead, we were able to demonstrate that it’s all a trick of memory. When you’re in a fearful situation, you’re laying down dense memories, and so when you read that back out, even just in the next moment, you say, what just happened, what just happened, it seems like you’ve got so much memory and just in a Bayesian manner, if you read that much memory, you assume that must translate to a longer time scale, and so everything is about how much footage you can draw on.

1:12:05 SC: And this does feed back into what you were saying earlier about the sort of different time scales going on in different processes in the brain.

1:12:12 DE: Exactly right. And when something really scary and life-threatening is happening, that’s when… That’s when you say, hey, I’m going to write this down, I’m not going to write this just in sort of la-di-da working memory, I’m going to burn this into the circuitry, ’cause this matters.

1:12:27 SC: And so this also, at least, I don’t want to say explains, but speaks to the fact that when we’re in lockdown and not able to do anything different from day to day, time seems to move really, really slowly from moment to moment, but in retrospect, once all this is over, it will seem to have not lasted that long.

1:12:43 DE: Exactly right, and that’s the experience all of us have had is it’s just unbelievable to me that this is October of 2020 already.

1:12:49 SC: It’s crazy, yes.

1:12:51 DE: And it’s because even though this whole COVID time has been full of various sorts of stressors for people, most of us are trapped in the same four walls, and we’re very location-sensitive for our memories, and so when they’re the same four walls, it’s really hard to distinguish one memory from another. And so when I think, okay, how much time has it been since… Since we shut down in February or something, and it’s very difficult to draw on clear footage, it’s not like, oh, yeah, this happened, then that happened and that happened. Instead, it’s just a big blur, like a mish of all the experiences that I’ve had at home. So it’s very difficult to estimate how much time has passed.

1:13:33 SC: I was almost just about to say that once we all get uploaded into the Matrix that we won’t need to worry about these pandemics anymore, but then I remembered there are such a thing as computer viruses, it would probably be much, much worse. Like probably the threats to us would be enormously greater if we were just in silico rather than in the physical world.

1:13:50 DE: Well, that’s right, although, as you know, we might already be there.

1:13:54 SC: I’ve heard that, yes, did a podcast on that too, with Nick Bostrom, too. So okay, well, you’ve given us a lot to think about. The book is called…

1:14:03 DE: Livewired.

1:14:06 SC: Livewired. And yeah, good luck with developing these technologies, so I really am fascinated by how this is going. The brain is complicated, as I started off saying, but we’re learning a lot about it, and it’s going to change the world when we really figure things out.

1:14:18 DE: Great, great. And if any listeners want to join our next developer contest, we’re going to announce it soon on neosensory.com, so think of what kind of sense you would want, what kind of universe you would want to experience, and then figure out how to program it with us.

1:14:34 SC: I like that. Alright, David Eagleman, thanks so much for being on the Mindscape podcast.

1:14:38 DE: Great, thanks so much, Sean.

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