Ep2 "What would you do with robotic wings? (or How to get a better body)"

Published Apr 3, 2023, 10:00 AM

How is it possible for a dog to become a champion surfer? Why does the world’s best archer have no arms? Why might someone come to believe that her leg doesn’t belong to her? How can we build robots that simply figure themselves out? In this episode, Eagleman unmasks mysteries about the brain's shocking flexibility -- revealing how it comes to drive whatever body it finds itself in, how it determines what the "self" is, and what this tells us about our future as humans.

Why does the world's best archer have no arms? How does a dog learn how to skateboard? How can a robot figure out what its body looks like? How can someone come to believe that her leg doesn't belong to her but to someone else? And what does any of this have to do with babies? Babbling or doc oc from spider Man. Welcome to innert Cosmos with me, David Eagleman. I'm a neuroscientist and an author at Stanford University, and I've spent my whole career studying the intersection between how the brain works and how we experience life. Have you ever texted while you're riding your bicycle? So on campus, i see students doing this all the time, and I'm amazed because what it tells me is how good the three pound brain is at controlling the body, running the petals with the legs, and steering the handlebars with one hand and hitting these very tiny targets with the other thumb, and pulling on the brake when they need to slow down, and so on. And this is all from inside the brain's mission control center in the skull, in total darkness. It's controlling all these limbs with a degree of expertise that we can't even scratch with robotics. So what I want to talk about today is how you can get even a better body. And I'm not talking about diet or fitness. I'm talking about the future of what we can do with our brains. For example, could you add new limbs. Let's start with the Spider Man comics from back in the day, So in July of nineteen sixty three, a new character got introduced. It was a scientist named Otto Gunther Octavius. Now he was interesting because he plugs a device directly into his brain to control four extra robotic arms. He's able to operate these metal limbs just as smoothly as his own natural arms, and so he's able to work this way with radioactive materials. Now in the comic book, each of his arms is able to operate independently, in the same way that you can steer your car with one hand while you change the radio station with the other. And this is while at the same time you're switching between the brake and the gas with your foot. Unfortunately, for doctor Octavius, there's an explosion and the explosion damages his brain and dooms him to a life of villany. So he's now lost all his sense of morality, and he capitalizes on these four extra arms to climb up buildings and pull safes out from walls and fight in new ways with multi hand combat. And now with his new evil personality, he becomes known as Doctor Octopus or doc OC. So when the comic book debuted in nineteen sixty three, it was pure sci fi fantasy to imagine that a human brain could control robotic limbs, but not anymore. So how close are we to actually reaching the point of a doc oc? Could you plug in new limbs like extra legs or wings? What are the limits? So to get started in understanding this, the key thing to orient ourselves too is that the brain has inputs and outputs. The inputs includes all the information from your senses like vision, hearing, and smell and so on. The output is how you're brain controls your body to interact with the world. In a different episode, I'll talk about input asking how our senses work and how we can create new senses. But today we're going to talk about how the brain controls the body and what the prospects are for changing that or adding on to that. So let's start back in the nineteen sixties when a Canadian neurosurgeon named Wilder Penfield was sticking small, thin wires called electrodes into the brain of a patient undergoing surgery. Now, it turns out you can stick things like that directly into the brain, and you can do that while the patient is awake and it doesn't hurt at all. Why it's because there are no pain receptors in the brain, so you can just dunk a metal electrode right in the tissue the way you'd stick a toothpick in a block of cheese, and the patient doesn't feel anything anyway. So Penfield was sticking the electrode into the brain while he talked with the patient and asking him what he was feeling. And what Penfield stumbled on was something that elevated neuroscience. He discovered in the brain a nap of the body. So let's say I have the electrode right here on a little strip of brain tissue where you'd wear a tiara or headphones, and the electrode is measuring the electrical spikes in the brain cells, the neurons, And now I touch your shoulder, and it turns out these neurons only respond to touch on your shoulder and nowhere else. So now let's say I move the electrode just a little bit over, still on this strip, and now I touch your elbow, and Penfield found that as he moved over a little more, there are neurons that respond to the forearm, and then next to that the hand, and elsewhere along this little strip of brain tissue he found cells that respond to your face, or your torso, or your legs or your feet. And so as you move along this strip in the brain you find the whole body represented where neighboring territories on the body have neighboring territory in the brain. And this came to be known as the somatos sensory cortex, which refers to sensation from the body, the soma. Now, the interesting part for today's podcast is that he also found a second map of the body, and this was on a neighboring strip that we call the motor cortex. It's right in front of that. So when the cells here are active, they drive very particular parts of the body. In other words, they contract particular muscles. So activity in these cells right here causes your shoulder to twitch, an activity right next to it causes your bicep to contract, and activity right next to that causes your forearm to move, and so on. With a map of the entire body, all the parts that you can control are represented in this strip here. Now, it turns out this map doesn't have equal representation everywhere. The body parts, which are more finely controlled, have larger areas of representation. So you have a bunch of territory devoted to your fingers, for example, but not a lot to the muscles that can move your kneecap or your scalp. Now we'll come back to this in later episodes, but what is wild is that this map of the body is not genetically determined as everyone originally guessed. Instead, it's shaped by the body's experience in the world. In other words, it devotes territory to what it can control. And if you lose your hand in a terrible car accident, your primary motor cortex begins to shift, often change itself. Over the course of weeks, the brain areas that control neighboring arm muscles like your biceps and triceps slowly take over the cortical territory that formerly operated your hand. Now we can look at it this way. Neurons that previously drove your hand, they get their job duty reassigned, and they now join the team of neurons that control the upper arm muscles. So what this tells us is that the motor areas of the brain, those neurons that are sending their signals down the spinal cord to drive the body, they optimize themselves to drive the available machinery. And this principle, as we're going to see, is what opens the door to rearranging body plans, something that's traditionally been done only when there's injury, but will soon enough be possible when we want to add things to the body. So to understand this, let's start with a wide angle lens looking at the world of our cousins in the animal kingdom. So the thing to notice is that there are all sorts of strange and amazing body plans. To look at the ant eater with its long proboscis, or an animal called the star nosed mole, which has essentially twenty two fingers on its nose with which it feels around in its dark tunnels. Or look at the sloth or the dragonfish, or the platypus or the octopus. You find very different bodies in the animal kingdom. But here's the thing to notice. All the animals, including us, have surprisingly similar genomes. So how do the animal's brains come to operate all this wildly different equipment like prehensile tails or claws, or larynxes or tentacles, whiskers or or wings. The question is are their brains preprogrammed for it? How do mountain goats get so good at leaping up rocks? And how do owls get so good at plunging down on mice? How do frogs get so good at hitting flies with their tongues? So here's what I think the answer is. In my book Live Wired, I proposed what I call the potato head model of the brain. And this model proposes that you can plug in whatever peripheral devices you want, like arms or fins or wings, just like plugging things into a potato head, and the brain will figure out how to drive them. It's kind of like with your computer. Your laptop manufacturer doesn't have to know the next model of peripheral that's going to come out in a couple of years. Your laptop is ready to drive anything whatever comes along. So in this potato head framework, mother nature has the freedom to experiment genetically with any kind of plug in play motor devices. You just plug in whatever limbs you want and the brain will figure out how to drive them. It doesn't matter if this is fingers or flappers or fins. It doesn't matter if your body shows up with two legs or four legs or eight legs. It doesn't matter whether you sprout hands or talons or wings. The fundamental principles of brain operation don't need to be redesigned every time. The motor system that we're talking about in the brain, well, it figures out how to drive the available machinery. So the advantage of such an adaptable brain is that it allows mother nature to mess around with genetics to develop new peripheral devices. And it turns out it's shockingly easy for her to make little adjustments to the a's and seas and teas and gees, and you end up with all kinds of different body plants. Okay, now, wait a mind it, you might say, If bodies are so easy to modify with tweaks of the genome, how can we don't see things like a human sometimes being born with a genetic mutation that gives him a tail or an extra arm. Well you do. Actually, it turns out that some genes in your genome act like movie directors. They carefully control which thing happens when and where, and in this case, which other gene cascades get triggered to unpack. So in fruit flies, a few decades ago, it was discovered that certain mutations in these director genes control the development of the larger body structure. One of the first discoveries involved a mutation in the fruit flies in which a pair of legs would grow where the antennae were supposed to be, and there's a reverse mutation which placed antennae where the legs should be. So when you start looking at the building of the body this way, you see it's sort of like lego. You can just swap one thing out for another. Based on these genes coated in a's and seas and teas and geese. If you want to look this up further, look up homeobox genes. The big point I want to make here is just that some genes act as a switch to turn on a cascade of other genes, and this is why many mutations involve the surprising appearance or disappearance of a full body part. So in humans you can find these surprisingly small mutations where, for example, a child is born with a tail, it's just a genetic program which extends the spinal column and keeps it going. Every year, there are hundreds of children born with tails, and the tail gets simply removed with an operation. In Live Wired, I tell the story of a baby named Gigi who was born in China a few years ago, and Gigi had three arms. Now, for the COGNISCINTI, I'll just mention that this sort of thing sometimes happens because of a parasitic twin in the womb, where one twin doesn't make it and gets absorbed into the body of the healthier twin. But that's not the case with Gigi. His genetics simply dictated the growth of a third arm. The surgeons in China took several hours to remove one of the arms because both arms on the left side were well developed and had individual shoulder blades. Now, what tails and extra arms illustrate is the way body plants can change with small alterations of the genetics. And it goes without saying that this sort of genetic wobble happens in minor ways all around us. Some people have longer arms, or stubby your fingers, or a big toe that's shorter than the second toe, or wider hips or broader shoulders. And although our nearest cousins, the chimpanzees, are nearly genetically identical to us, they have a lot of differences in their body plan. For starters, their bicep muscle has a higher insertion point, and their hips are turned more outward, and their toes are much longer. Now, the point is that the chimpanzee brain, with its mere ninety thousand genes, doesn't have to be reinvented to figure out how to drive a chimpanzee body to swing in trees and to walk on knuckles. And by the same token, the human brain doesn't have to be reinvented to figure out how to play pickleball or dance hip hop. In both cases, the brain just figures out how to best drive the machinery that it has. So to understand the power of this principle, consider Matt Stutsman. This is a guy who is born without arms. He found himself really attracted to archery, so he learns to manipulate a bow and arrow with his feet. What he does is notch the arrow into the string with his toes. Then he lifts the bow with his right foot, and he's got a strap around his neck which connects the bow to his shoulder, and that allows him to position it at eye level. And then he puts tension on the bow by pushing it forward with his foot, and when his aim is on target, he lets the arrow fly. Now, the thing is that Matt is not simply talented at archery. He is the best in the world. As of this podcast, he holds the record for the longest accurate shot in archery. And that's probably not what his doctors would have predicted for a baby who came out of the womb without arms, But perhaps they didn't realize how readily his brain would adapt its resources to solve problems in the outside world. Now we see this sort of flexibility everywhere in the animal kingdom. Consider this incredible dog whose name is Faith, who was born without front legs, and she grew from puppyhood to be able to walk on her two hind legs bipetally the way that a human walks. You can find YouTube videos of her walking around. It's totally amazing to watch. And although we might have guessed that dog brains come hardwired to drive standard dog bodies, Faith shows us how readily brains will move around the world with whatever machinery they find themselves in. So what we see from Matt or from Faith the Dog is that brains are not predefined for particular bodies. Instead, they adapt themselves to move and interact and succeed in the world. And this isn't simply about the body you're born in, but about whatever opportunities might come along. So take Sir Blake, a bulldog here in California who's mastered skateboarding. He steps up onto the skateboard and with his front paw he scrapes at the ground to get momentum, and at the right moment, he sets his front paw onto the board and he leans into the ride, and he shifts his body weight to steer the board around obstacles, just like a human wood. And when he's done, he lets the skateboard slow down almost to a stop, and then he dismount. Now, given the absence of wheels in the evolutionary history of dogs, what this shows is the adaptability of brains to steer new possibilities. Or take this other dog named Sugar who took up surfboarding and is inducted into the International Surf Dog Walk of Fame, or on second thought, forget Sugar and just revel in the fact that there is an International Surf Dog Walk of Fame, because there are lots of dogs that do this, and we don't usually think about studying dog brains in the context of how they hang ten on a longboard, but you can, because all the dog requires is the opportunity and their motor systems will figure it out. So how do these dogs do it? And what does this have to do with a baby babbling? Well, a baby learns how to shape its mouth and breathing to produce language. But this is not from genetics, and it's not by studying a book or surfing Wikipedia. It's from babbling. They listen to what's going on around them, and they try things out, and their brain compares how close their own sound was to what they're hearing from the adults around them. And this has helped long because they get positive reactions for some utterances and not for others. And so there's this constant feedback loop, and that allows babies to refine their speech to perfection in whatever language is being spoken around them, whether that's English or Chinese or Hindi or any of the seven thousand languages spoken around the globe. In exactly the same way, the brain learns how to steer its body by motor babbling, in other words, babbling with its slims. Just watch a baby in the crib. She bites her toes, she slaps her forehead, she tugs on her hair, she bends her fingers, she knocks on the bar of the crib, and so on. And by doing this, she's learning how her motor output corresponds to the sensory feedback she receives. And in this way, she's learning to understand the language of her body, how her outputs nap onto the next inputs. She's trying things out and she's getting feedback, and this is how she eventually learns how to walk and navigate food to her mouth, and eventually swim in a pool and dangle on monkey bars and master a cartwheel. She's trying things out, she's adjusting, she's motorically babbling. And even better, we use this same method to attach extensions to our bodies. So think about riding a bicycle, which is a machine that our genome presumably did not see coming to master bike riding. Have to carefully balance your torso, and you change direction by moving your arms, and you have to stop by squeezing your hands, and this is all totally different from the way we normally move. But despite these complexities, most five year olds can demonstrate that the extended body plan is easily added to the resume of their motor cortex. And this isn't just limited to typical bicycles. Consider the sky named Deston Sandlin. He's an engineer who has given this very strange bicycle by a friend. It had this elaborate gearing system so that if you turned the handlebars to the left, the front wheel would turn to the right, and vice versa. And so Deston was fairly sure that this wouldn't be too difficult to master because the concept is very straightforward. You just steer the opposite direction that you want to go. But as it turned out, the bicycle was just too difficult to ride because it required unlearning the normal operation of a bicycle steering wheel and training his motor cortex to master this new task was not as simple as having a cognitive understanding. In other words, he knew how the bicycle worked, but that didn't mean he could do the right thing with his body. But after some weeks he began to get the hang of it. He practiced every day, and each time he'd try to move, he would get feedback from the world, like you're falling to the ride, or you're crashing into a trash can, or you're swerving in front of the mail truck. And so he used that feedback to adjust his next moves, and after several weeks of practicing, he got pretty good at it. And he did this the same way that he learned how to ride a normal bike as a kid, by motor babbling. And by the way, you know what this is like If you drive and you go to a country that has the steering wheel on the other side of the car, if you or an American in England or vice versa, you keep swerving the wrong way, but you eventually get better because your visual system looks at the consequences of each action and adjusts things accordingly. It's just how Matt Stutsman learned how to shoot bows or sugar learned how to skateboard. Motor babbling is not only the way that babies and bicyclists learn, it's also become a new approach in robotics. So take this starfish robot developed by my colleague Hodd Lipson. The idea is that it's a very simple robot. It's just a small square body with four arms that stick out. The key is lips and doesn't teach it how to use its body. It figures itself out. The starfish tries out a move the way that an infant might flail a limb, and it analyzes what happens. In the robots case, it's just using gyroscopes to see how the move tilted the central bot. So if it does just a single move, that can't tell it what its body looks like and how it interacts with the world. But that feedback narrows the space of possibilities, so it now has a smaller space of hypotheses about what its body looks like. So now it does the next move, and the next and so on, and instead of choosing random movements, it chooses its next move to do a good job distinguishing the available remaining hypotheses so by doing this over and over, by motoric babbling, it develops a clearer and clearer picture of its body. In this way, it learns itself. You don't need a preprogram this robot. It learns its own capabilities. And what's wild is that if you snap off one of the legs of this robot, it'll figure itself out again. And it turns out that building a babbling, self exploring robot is way more flexible than preprogramming the robot. And in the animal kingdom, nature only has some tens of thousands of genes to work with to build a creature, so it can't possibly preprogram all of the actions that one might do in the world. So it's only choice is to build a system that figures itself out. Now, think about the stories that we just talked about with Matt Stutsman, the archer with no arms, or the skateboarding dog or the surfing dog or the starfish robot. What they all have in common is the same principle, whatever kind of way that you can move around in the world, the brain on the inside does not have to be redesigned. It just recalibrates to maximize what it can do. It figures out how to control whatever body it's in. A live wired brain doesn't need to be redesigned if there's a genetic change to the body, planet just adjusts itself. And that is how evolution can so effectively shape animals to fit any habitat in different environments. Animals will evolve hoofs or toes or fins or forearms or trunks or tails or talons, and Mother Nature doesn't need to reinvent the principles of the brain or do anything extra to make the new animal operate correctly. And you know what, Evolution really couldn't work any other way. It couldn't operate quickly enough unless body plan changes were easy to deploy and brain changes just followed without difficulty. And this massive flexibility is why we can so easily install ourselves into new bodies. If you ever saw the movie Aliens from a long time ago, you may remember this climactic deathmatch that the hero Ellen Ripley has with this giant, slimy alien. So she scrambles into this enormous robotics just like a mech suit that allows her movements to be magnified into these powerful metal arms and legs, and at first, she's swinging around awkwardly, but after some practice, she's able to land punches right on the alien. Now what we see is that Ripley learns how to control her new gargantuan body plan, and she does so thanks to her brain's capacity to adjust her relationship between her outputs like swinging my arm and her inputs. Wears that giant arm right now. So it's not difficult to learn these kinds of new associations. Just think about forklift drivers who are using their arms and these little levers to control something really large, or crane operators who are sitting in their little booth and operating this thing that's one hundred feet high, or laparoscopic surgeons who are controlling levers to control something that's very very tiny. So all of these folks get out of bed every morning to pilot strange new bodies. And let's take another example. There was a very successful young man named Jean Dominique Bobie who lived in Paris, and he was on top of the world. He was editor in chief at El magazine in Paris, and he revolved at the top of French social circles. And one afternoon in nineteen ninety five, without any warning, he had a massive stroke and he instantly fell into a deep coma. So he stayed in this coma for twenty days, and just when everyone was giving up hope, he regained consciousness. But there was a problem. It's the type of thing that gives everyone who hears about this nightmares, which is that he was mentally aware. He could see his surroundings, he could understand everything everyone was saying, but he could not move. He couldn't twitch his arm, his fingers, his face, his toes. He couldn't speak, he couldn't cry out. He discovered that his only available action was to blink his left eyelid. Other than that, he was locked in the frozen dungeon of his body. This is called locked in syndrome. So luckily he had a heroic nurse with a plan. She would sit with him and recite all of the letters in the alphabet in the order of their frequency, and he would blink his eye when she arrived at the next letter he wanted, and in this way, one letter at a time, he could communicate, and eventually he wrote out an entire book called The Diving Bell in the Butterfly. He died just before I was published. But this became a huge international bestseller, in part because it allowed readers to appreciate, probably for the first time, this simple pleasure of having a brain that successfully drives this enormous meat robot, and does so with such expertise that were totally unaware of the massive operations running under the hood. Now here's the question, what if we could have measured the little electrical signals in Bobie's brain, the spikes and his neurons, instead of having to look just at his eyeblinks. What if we could have eaves dropped on his neural circuits to figure out what they were trying to say to the muscles, and then by passed the injury to make something happen in the outside world. Well, a year after Bobie's death, researchers at Emory University implanted a brain computer interface into another locked in patient named Johnny Ray, and Johnny Ray lived long enough to control a computer cursor simply by imagining the movement. His motor cortex was unable to get the signals through the damaged spinal cord, but this implant could listen to the signals and then pass along that message to the computer. Then, in two thousand and six, a paralyzed former football player named Matt Nagel was able to control lights and open an email, and play the video game Pawn and draw a circle on the screen. And this was all because of a four by four millimeter grid of almost one hundred electrodes implanted directly into his motor cortex. He would imagine moving his muscles, which caused activity in his motor cortex, and the researchers could measure that activity to at least crudely determine the intention. The technology used with Johnny and Matt it was makeshift and unpolished, but had proved the possibility, and by twenty eleven, my neuroscience colleague Andrew Schwartz and his colleagues at the University of Pittsburgh built a prosthetic arm was almost as sophisticated and lie as a real arm. And a woman named Jan Schumann had become paralyzed from a disorder called spinocerebellar degeneration, and she volunteered herself for a neurosurgery that would give her control of this arm. So, with the signals recorded from her motor cortex, Jan imagines making a movement with her arm, and the robotic arm moves. This robotic arm is part way across the room, but this makes no difference because through the bundle of wires that attaches these electrodes in her brain to the computer and to the robotic arm, she can make it turn and grasp, essentially the way that she would have done with her own arm years ago. Normally, when you think about moving your arm, the signals traveled from the motor cortex down your spinal cord, into the peripheral nerves into your muscle fibers. With Jan, the signals recorded from the brain just take a different root. They're going long wires connected to motors instead of neurons connected to muscles. So Jan gets better and better at using the arm, in part because of improving technology, but also because her brain is rewiring to understand how to best control its new limb, just as it would with a reversed bicycle or a surfboarder Ellen Ripley's mex suit. Jan is doing motor babbling to figure out how to drive the arm smoothly, and in an interview, by the way, Jan said, I'd so much rather have my brain than my legs. Why did she say that. It's because if you have the brain, you can build a new body, but not the other way around. So we see that brain machine interfaces can restore or replace damaged limbs, But the question is could you use this same technology to add an additional limb. So in two thousand and eight, a monkey with two normal arms used its thoughts to control a third arm made of metal. This was again the work of my colleague Andrew Schwartz. He and his team put a tiny array of electrodes into the monkey's brain, and when the monkey thought about different things, that could control the robotic arms to pluck marshmallows and stick them in his mouth with the robotic arm. The monkey initially trained for this by moving a cursor on the screen towards a target, and he'd get rewarded when he got it right. And at first, the monkey would move his own arms while he was doing the task. But something remarkable happened, which is eventually he stopped moving his arms and the cursor continued to move on its own. His brain was rewiring to separate out these tasks, so some neurons corresponded to his real arms and some to the cursor on screen. Eventually, these signals were able to be used to control the robotic arm for marshmallow gathering and sticking in his mouth, all without any physical movement of his real arms. It had become a new limb, a third limb. The way that the monkey learned to use the robotic arm independently of its real arms recalls docc the character from Spider Man, who controlled his robotic limbs even while doing other tasks with his flesh hands. So it shouldn't seem surprising that humans and monkeys can figure out how to move robotic arms with their thoughts. It's the same process by which your brain learned to control your natural, fleshy limbs. As we've seen. Your process as a baby was to flail your appendages around and bite your toes in grass your crib bars and poked yourself in the eye and turn yourself over. For years, this is how you fine tuned the operation of your machinery. Your brain sends out commands, compares those with feedback from the world, and eventually learns the capabilities of your limbs. So your skin covered arm is really no different from the clunky, silver robotic arm of the monkey. It just happens to be the standard operating equipment you're used to, so you often end up blind to its amazingness. So for both jan and the monkeys, the robotic arms were not directly connected to their torsos, but instead connected by a bundle of wires. The electrodes in their brain sent wires to a computer which does the processing, and then the bundle of wires goes from the computer to the robotic arm. But increasingly this can be done wirelessly, and that means the robotic arm that you're controlling does it need to be right next to you or even in the same room. So could you control a robot on the other side of the world. While in two thousand and eight, my colleague Miguel Nikolaylis and his team from Duke University hooked up electrodes to a monkey and that monkey controlled the walking patterns of a robot halfway across the globe. So the monkey would walk on a treadmill, and the signals from his motor cortex were recorded and translated into zeros and ones and transmitted via the Internet to a laboratory in Japan and fed into a robot there. And while the monkey walked, the five foot tall, two hundred pound robot would also walk like a metal doppelganger. So after they demonstrated this proof of principle, the Duke team stopped the treadmill. But as the monkey looked at its avatar on the screen, it's thought about walking, and so the robot Japan kept marching along. So in the same way that Jan imagines movements and the arm executes our internal commands, the monkeys motor cortex continued to think about walking even while he wasn't doing it, and the robot kept going. So in the not too distant future, it seems inevitable that we're going to have mind controlled robots in factories or underwater or on the surface of the moon. And it's all from the comfort of our own couches. And this is because our cortical maps, after extensive training, will be able to incorporate whatever the limbs of the robot are. That's going to become our tell limbs. So think about the way we watch television, which means far sight. I'm coining the term tell limbs because in the near future, we're going to be control rolling far bodies. So the bodies that we have right now have evolved for the conditions of this particular oxygen rich planet. But leveraging the brain's plasticity to build long distance bodies, that's surely going to be our main strategy for space exploration. So what consequence would expanding your body, say with a robotic arm or a metal avatar across town. What consequence would this have for your conscious experience? The answer is that the robot will be perceived as a part of you. The robot will just be another limb. Now, it's an unusual limb because of the physical gap between you and it, but it nonetheless will qualify just as a new limb. The only reason we're accustomed to connected limbs is that Mother Nature is a talented seamstress with muscle and sinew and nerves, but she never worked out how to control distant limbs via bluetooth. Now, if extra limbs or telelimbs, if the seems exotic, recall that you have everyday experience with them. Just look in a mirror and move your arm. You see a distant object, move in perfect synchrony with your motor commands. And although babies are at first confused by mirror images, they come to understand the reflections as themselves, because although they don't feel any direct sensation from those distant limbs, they can witness their control over them, and that's enough for these limbs to be annexed by self hood. So this notion of this self is analogous to the borg in Star Trek, who assimilate everything in their path into their singular identity, except for those things that can't control, like the impossibly unpredictable Captain Picard. Now this led me to propose an axiom in Live Wired about the nature of selfhood. What the body can control becomes the self. And I think this all pivots on predictability. In other words, can I predict that signals from my brain will cause something to happen out there? So this relationship of selfhood and predictability it allows us to understand disorders such as asmatic noosa, which translates to not knowing one's body. So in asmatic noosa, damage to the right pridal lobe of the brain, say by a stroke or a tumor, means that a person is no longer able to control a limb, and as a completely gobsmacking result, the patient will deny that the limb belongs to her, and sometimes will insist that the limb belongs to someone else. She will attribute the arm to a dead friend or a relative, or a phantasm or a devil, or one of the medical professionals taking care of her. She'll say that it's not her arm. She'll explain that her own real arm was stolen or is simply missing. The manifestations of this can be varied and strange, So a patient may feel totally indifferent towards her no longer self limb, or she might be delusional about it and come up with strange fabrications to explain what happened, such as saying someone's so this onto my body, or other patients might sympathetically describe their limbs as something that they dislike, like a deadweight. And in a more vicious version of this breakdown of selfhood, a patient may hate her alien limb, and she might curse at it and hit it. So there's no gold standard for this disorder, but you probably have no trouble guessing my proposal in Live Wired, which is the brain can no longer control the limb, and so the limb falls from the brotherhood of the self. It no longer is part of you. Now. Sometimes these patients will have a small window of lucidity in which they re recognize their limb as their own, but it doesn't last long, And I hypothesize that this may result when the arm happens to behave like they intended. So it's accidental predictability. Given a person's lifelong experience of controlling her arm, it doesn't come as a surprise that even a temporary impression of control can snap it back into alignment with this self, if only for a moment. Now, by the way, I suspect this sense of predictability is related to the way that a person that you know deeply, like a family member, becomes something like a part of yourself. Of course, humans are way too complex to predict perfectly, and the degree to which your spouse acts surprisingly is the extent to which he or she remains independent. Okay, Now, one doesn't need prosthetics or brain surgery to try out new bodies. The developing field of avatar robotics allows the user to control a robot at a distance, seeing what it sees and feeling what it feels. So take something called the shadow hand, which is one of the most intricate artificial hands in existence. Each fingertip is equipped with sensors which feed their data back into haptic gloves that are worn by the user, So sending data over the internet, one can control a robotic hand. In London from Silicon Valley and other groups are working on disaster recovery avatars. These are robots that are sent in after earthquakes or terrorist attacks or fires, and the ideas that they can be piloted by drivers that are sitting somewhere else that's safe. Now, I haven't yet heard of people using strange bodied avatars, but they certainly could. Just as the brain learns skis or trampolines or pogo sticks, it can learn to become one with a weird and wonderful avatar body. So this field of avatar robotics is going to allow people to try out extended or strange bodies. But let's note that it's super expensive and luckily there's a better way to try out different body plans, and that's inside virtual reality. So inside a simulated space, you can make massive changes to your body plan instantly, inexpensively. So imagine looking into a mirror in your VR world, you lift your arm, and you see your virtual avatar in the mirror, raise its arm, you tilt your neck in the avatar tilts its neck. Now, imagine that this avatar has not your face, but that of an Ethiopian woman, or a Norwegian man, or a Pakistani boy, or a Korean grandmother. So, for the reasons that we just saw about how the brain determines selfhood, if I can control what it does, it becomes me. It only takes a few moments of motor babbling in front of this VR mirror to convince yourself that you now inhabit a different body. You can then walk around in the VR world as a different in person, experiencing life through a modified identity. Self identity, by the way, is surprisingly flexible. Researchers have been studying this in recent years, how taking on the face of a different person can enhance empathy, but taking on a new face that's just the beginning. So in the late nineteen eighties, because of a coding error, the VR study of unusual bodies began. A scientist was inhabiting the avatar of a dockworker in VR when a programmer accidentally made his arm enormous, like the size of a construction crane because he inserted too many zeros into the scaling factor. And to everyone's surprise, the person in VR was none less able to figure out how he could operate accurately and efficiently with this megaarm. And so this led people to wonder what kind of bodies could be occupied. So my friend Jaron Lanier and his colleague An Lasco made an experience in which people inhabited the bodies of eight legged lobsters. So your two arms controlled the first two arms of the lobster, and then they tried out several complicated algorithms to control the other arms. And it was pretty tough work to control the eight legs of the lobster, but apparently some people were able to make it come to pass. So Jaron coined the term homuncular flexibility. The homunculus is the little man inside your head, the little naps. He coined this term homuncular flexibility to capture the surprising elasticity of the brain's representation of its body. Some years later, my Stanford colleague Jeremy Baylinson and his team set out to test homuncular flexibility more scientifically. They asked whether people could learn to act accurately control a third arm in VR. So imagine strapping on the VR goggles and you grasp two controllers in your hand, and so you can see your own arms in virtual space, and you see an additional arm as well, coming out from the middle of your chest. The task is pretty simple. You touch a box as soon as it changes color. But there are a lot of boxes, and to do well you have to employ all three arms. So the first two virtual arms are simply controlled by your own arms, and the third arm is controlled by rotating your wrists. Within three minutes, users got it. They could accommodate the new body plan with this third arm and do the task really well. There's really no limit to the physiques or body plans that you could explore. Imagine finding a virtual tail protruding from your tail moan which you could accurately control with your movement, or becoming the size of a golf ball or the size of a building, or having six fingers, or becoming a housefly with wings, or like doc oc, becoming an octopus. Marrying the flexibility of the brain to the burgeoning creativity of the VR design world. This is why we're moving into an era in which our virtual identities are not going to be limited by the bodies that we happen to have evolved. What we can do instead is speed up evolution from eons to hours. We can explore bodies that Mother Nature couldn't dream of, making virtual avatars reel to the brain. So let's wrap this up. We saw with Matt the archer or Faith the dog that brains adjust to drive whatever body they find themselves in, and like Jam's robotic arm, brains can also figure out how to operate new hardware additions. Massive networks of brain cells pull off this trick by putting out motor commands like lean to the left and assessing the feedback like the skateboard tilted and wobbled, and then it adjusts its parameters to climb the mountain of expertise. So our progeny won't have to limit themselves to the boundaries of their bodies. Instead, they're going to be able to extend across the universe according to whatever is under their control. Imagine learning how to control a drone as part of your body, or build robotic wings and control them with your thoughts, just how you control your arms and flying across the city that way, or imagine having a sail for balancing, or a propeller or peripheral devices like a forklift. How would you build a better body than the one you inherit it from a long road of evolution. That's all for this week. To find out more and to share your thoughts, head over to eagleman dot com, slash podcasts, and you can also watch full episodes of Inner Cosmos on YouTube. Subscribe to my channel so you can follow along each week for new updates until next time. I'm David Eagleman, and this is Inner Cosmos.

Inner Cosmos with David Eagleman

Neuroscientist and author David Eagleman discusses how our brain interprets the world and what that  
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