Science Friday - How Does The Brain Control Your Every Move? July 21, 2023, Part 1

Episode Date: July 21, 2023

We have a new podcast! It’s called Universe Of Art, and it’s all about artists who use science to bring their creations to the next level. Listen on Apple Podcasts, Spotify, or wherever you get your podcasts. Astronomers Spy A Two-Faced Star This week, astronomers report in the journal Nature that they’ve discovered a white dwarf—a dying star’s dense inner core—that, instead of being uniform in composition, has a surface that appears to be hydrogen on one face and helium on the other. The star rotates on its axis once every 15 minutes, bringing each face into view. Researchers spotted the unusual object with an instrument called the Zwicky Transient Facility, which initially singled out the star because of its rapidly changing brightness. The astronomers aren’t sure why the white dwarf, which they’ve nicknamed Janus after the two-faced Roman god, has this strange divided surface. Some possible theories include shifting magnetic fields which produce areas of different density, or that it’s a step in stellar evolution only partially complete. Tim Revell, deputy US editor at New Scientist, joins John Dankosky to talk about the two-faced star and other stories from the week in science, including the resignation of the Stanford University president amidst an ethics probe, discovery of ancient natural graphene, an earthworm invasion in the Arctic, and investigations of alcoholic fruit. How Does The Brain Control Your Every Move? As you read this, every small action your body makes—eyes scanning the page, fingers scrolling a mouse, scratching an itch on your face—must be dictated by your brain. These actions usually happen without a second thought. But inside the brain, the motor cortex is hard at work making the body move. For nearly a century, every neuroscience student came across the “homunculus”—a visual representation of which areas of the brain control certain body parts. But for the last few decades, some researchers have disputed this traditional view of brain mapping. This includes a recent study, led by Washington University in St. Louis. Joining guest host John Dankosky to discuss how the brain and body are connected are study lead author Evan Gordon, assistant professor of radiology at Wash U., and Michael Graziano, professor of psychology and neuroscience at the Princeton Neuroscience Institute in Princeton, New Jersey. To stay updated on all-things-science, sign up for Science Friday's newsletters. Transcripts for each segment will be available the week after the show airs on sciencefriday.com.   Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Listener supported WNYC Studios. This is Science Friday. I'm John Dankoski in for Ira Flato today. A bit later this hour, we're going to talk about how the brain controls movement and what that means for neuroscience as a whole. But first, imagine a globe that if you look at it from one side, it was all land, and when you spun it around, it was all water. This week, astronomers report in the journal Nature

that they've spotted a white dwarf, that's the dense, core of a dying star. That's the stellar equivalent of that globe. This star has a surface that appears to be all hydrogen on one face, all helium on the other. Hmm. Joining me to talk about that and some other short subjects in science is Timothy Revel. He's deputy U.S. editor at New Scientist and he's right here in our New York studios. Welcome back to the show. Tim. It's good to see you. It's great to see you too. Okay, so first of all, I guess tell us more about this star, this weird star. Yeah, it's absolutely amazing. So it was spotted about 1,300 light years

away from Earth, and it rotates about once every 15 minutes. And that means we get to see it's two different sides a lot. And so there were researchers at the Zwicki Transient Facility in California. They were looking at the sky, just a standard observation of the sky, and then

they suddenly spotted this very strange looking star. And as you say, on one side, it's completely helium and on the other side completely hydrogen. So they found this just on a random sky, scan, but I assume that they've confirmed this with some other fancy instruments by now. Yeah, exactly. So they confirmed it with other telescopes, and they confirmed it using spectrometry, which is a sort of chemical fingerprint of the star, and that allowed them to see

what chemicals were mostly composed on the surface. Okay, so they can see it, they can understand basically what it is, but do they know why this has happened? Yeah, we don't know why it's happened. We know that with white dwarfs, they can transition from being mostly helium to mostly hydrogen on the surface and that happens at a fairly regular, irregular occurrence. And so maybe we've just caught it in the middle. We've caught it in a slightly strange moment. But what the astronomers who spotted this reckon instead is that maybe that the magnetic field has slightly gone off kilter and it's a bit stronger on one side than the other. And what would happen is that would mess with the internal convection inside the star, the sort of churning that happens of the gases. And then maybe that

means that you end up with more helium on one side and more hydrogen on the other. That's so interesting. Of course, there's so many space observers and space interested folks in our listening audience. I'm sure that they're going to ask, can I look at it myself? I think it's going to be very difficult for you to see it yourself unless you have an amazing telescope. But if you could see it, if you were right there and you could have a look at it, something that you would see is that it would be bluish, and then the helium side would look a little grainy and the hydrogen side would be very smooth. And did they think that there's any more of these things out there?

We don't know. This is the first one we've ever spotted. That's what's so amazing about it. We've never seen a two-faced star like this before. But now we know what it looks like, but potentially we can scan the skies for a few more. And maybe there's more out there, but certainly it seems rare. That's very, very cool. Okay, so let's go to another story about chemical elements of the form of carbon known as graphene. Why don't you tell me about this first? Yeah, this discovery absolutely blew my mind. So you might remember in 2004 that human, we created graphene, which is this sort of wonder material that's a single layer of carbon. It's one atom thick, and it's meant to be incredibly strong, 100 times stronger than steel,

and it has amazing electroconductivity. But when we found it, we thought, well, we've just invented this now. This is an amazing new material. Go humans. Yeah, go humans. But now it seems like nature has gone into the lead. It turns out nature discovered graphene at least 3.2 billion years ago. We've only just found that out now.

Interesting. Okay, so first of all, how exactly did they find this out? Yeah, so researchers were just looking in this gold mine in South Africa. And under some rocks was a sort of interesting looking material. They took it back to the lab and looked at it under a microscope. And they were pretty shocked to find out that graphene, this amazing material, there it was in this mine. So we now have learned how to make graphene ourselves. Does it, I don't know, does it get us anything fancy because we're able to get it in nature now? Yeah, so this is what's particularly interesting about the discovery, other than just the scientific wonder of it,

is that graphene was originally discovered with some graphite from a pencil and some sticky tape, a really basic way of making it. Because it's such an amazing material, we want to be able to make it in vast quantities. And the industrial processes for making them use extremely high temperatures, up to about 1,800 degrees Fahrenheit. And with this naturally occurring graphite, graphene, sorry, it seems that it occurred. from a combination of bacteria dying and then undergoing some chemical reactions. But these chemical reactions occur only at about 500 degrees Fahrenheit. So much, much cooler. So maybe we'll find a much more energy efficient way to make this amazing material off the back of it.

But it was found in a gold mine. Is this something that you can mine for? Yeah, potentially. It's like such early stages at this point that they've just, you know, they've got a few little samples, they've got some graphene there. The graphene seems to be slightly different to the graphene that we have created in the lab. There's a slightly different color, so maybe it's got some other elements in it. But, yeah, I think most likely is that it will inform how we can make it on an industrial scale,

but mining is certainly not ruled out at this point. Very interesting. Okay, so later this hour, we're going to be talking about the brain and how it directs the movement of our body. But there's some other brain news this week, and it's about consciousness and what exactly it might be in the brain. What can you tell us that this is a big idea? Yeah, it's a really big idea. And so any progress on this, even if it's small, seems like big progress. And what we have now is a stronger evidence for one of the explanations potentially for how consciousness arises in the brain.

And so there are many competing ideas about consciousness and how it arises. But one of them is called IIT, and that stands for integrated information theory. It's a pretty technical and very maths-heavy theory. But one of the things it says is that when two things interact, if that produces more information than there was at the beginning of the interaction, that is consciousness. That is like the beginnings of consciousness. And so researchers have now tested this theory to see whether it does work in the way that IIT predicts. And what they did was they looked at brain scans from 17 people in four different states of consciousness.

There was awake, mildly sedated, unconscious, and in a recovery stage from an anesthetic. And what way they found was this sort of calculation that you can do in IIT, which produces a number called phi. they found that it relates to consciousness in the way that you would expect. So higher consciousness increases with phi, and then consciousness also decreases when you've got a lower number. When you're talking about that, the first thing I think about is it seems like a fairly, in some ways, simple formulation that could apply to animal consciousness?

It could apply to machine consciousness, I suppose. Yeah, this is the thing about the theory, is that it only tells you about these interactions between like two things. and then maybe you can build them up to a higher level. But the brain consists of billions of neurons. And the mathematics is so complicated that we can really only perform the calculations at the moment for a few components.

And so what they did in this study was they worked out a way in which you can simplify the brain to sort of look at regions rather than the neurons itself. And that matched the theory, but it's such like it's so complicated that it's really just like a bit of inching forward. Potentially this is the strongest theory we have for consciousness, but it's a long way yet before it'll be proven.

Yeah, I was going to say it's a long way before it can be proven. This is something we've been thinking about as humans for quite some time, so the debate is not settled here. No, it's not settled. There are other people who think there are other stronger theories, but this is some new evidence that we didn't have before. So there's some news this week out of Stanford University, really interesting news,

that the Stanford University president has had to resign following an ethics probe, and it's a science ethics probe. Tell us what's going on here. Yeah, so Stanford president is Mark Tessier Levine, and he's a pretty notable neuroscientist who's published more than 200 papers on degenerative brain disease. But he said he's now going to resign after an independent report concluded his research contained, and this is a quote, multiple problems and fell below customary standards of scientific rigor. So the report, it took in 50 interviews and had over 50,000 documents as part of the report.

And they said that the Stanford president's labs had inappropriately manipulated research data and in several instances he himself hadn't taken proper steps to correct mistakes. My goodness, this is quite a story which will continue to follow. Let's go to some animal news, Tim. Two new species of saber-tooth cats have been discovered. This is interesting. Yeah, this is amazing. So saber-tooth cats, they roamed the earth from about 56 million years ago to about 10,000 years ago.

And we already know that there were about two dozen species that we know of. And so researchers are still trying to work out exactly which saber-tooth species is lived where and when. And so a team re-examined a large collection of fossils from near Cape Town in South Africa. And those fossils actually were originally unearthed 40 decades ago,

but they've just had another look at them. Four decades ago, and they've just had another look at them. And from the team's analysis, they were able to identify two medium-sized saber-tooth species that were different from any of the others that we know of. Interesting. Okay. So this is a really important thing.

Yeah, it's a really important thing. And like we know a little bit about from this analysis what the saber-tooth cats would have been like. So one of the species we could tell from the sort of shape of its skull that it was probably a bit like a leopard and hunted prey in the forests. Whereas the other one was much more of a runner and it sort of hunted like a cheetah, which is an absolutely terrifying prospect of cheetah with saber-tooth fangs coming at you. I can't even imagine. It actually stirs the imagination a bit. Okay, before we run out of time, we're heading into the weekend here. and if you've been considering a fruity drink of some sort,

you've brought us a story about alcohol and tropical fruits. Okay, tell us about this. Yeah, this is great. So plants in tropical forests, they seem to have a pretty cunning technique for luring mammals to eat their fruits and distribute their seeds. And it's a technique that often works for humans too, and it's alcohol.

So it seems that there was these researchers and they collected a wide range of fruits from a Costa Rican tropical forest. and then they sampled the alcohol content of all these different fruits. They found 80% of them had some noticeable alcohol in them. But then when they looked at which animals ate which fruits, they found that those with higher levels of alcohol were much more likely to be eaten by mammals.

So in some ways that's not surprising, right? Yeah. So the alcohol, it comes from like this, from natural yeast turning the sugars into alcohol. And so the fruits in which that happens most are the ones that are ripest, the ones that have the most sugar and ultimately the ones that have the most nutrition. So maybe that's what enticing the animals. It could be the taste of alcohol.

It could be the taste. I mean, how much alcohol are we talking about? Are we talking about like sort of little tipsy monkeys in the jungle here? We're talking about a very low amount of alcohol. So the highest concentration of alcohol in any of these fruits was in the hog plum, which I never tasted before, but I would be up for trying. And that one had 1.5% alcohol. And most of them were much lower.

So I think only very small animals that eat a lot of fruit would really be noticing the intoxicating effects. You've never had hog, plum, brandy. It's such a delicacy. Well, I must have it with you sometime. Thanks for bringing us all these stories, Tim. I really appreciate it. Thanks for having me. Tim Revel is Deputy U.S. editor at New Scientist. We've got to take a break here. When we come back, a breakthrough in our understanding about how the brain controls movement in our bodies.

And we're going to be taking your phone calls as well, 8447, 7, 2.4. 8255. That's 844-Sye Talk. We're going to be right back after this short break. This is Science Friday. I'm John Dankoski. I want you to now become hyper aware of what you're doing right now. Are you driving? Are you washing the dishes? Are you going for a walk? Odds are you weren't really thinking about what you were doing until I just asked you. Every little action that your body takes has to be dictated by your brain, from your eyes scanning the space in front of you, to your legs moving one in front of of the other, and this all usually happens without really thinking much about it at all. So this is a very complicated process in the brain, and one that still has a lot of mysteries to it. We'll try to

unpack some of those mysteries with two researchers today. Dr. Evan Gordon is assistant professor of radiology at Washington University School of Medicine in St. Louis, and Dr. Michael Graziano is Professor of Psychology and Neuroscience at the Princeton Neuroscience Institute in Princeton, New Jersey. I'd like to welcome you both to Science Friday. Hello. Hello. Thank you very much for having me on, John. Of course.

Thank you for being here. And we're going to take some of your listener questions as well. What do you want to know about how the connections are made between our brain and our body? If you have questions, give us a call. Our number is 844-724-8255. That's 844 SciTalk. Or you can always tweet us at SciFri. So, Michael, I want to start with you.

And maybe we should start with an explanation of a really important part of the brain. This is the motor cortex. Give us a basic idea of what exactly it is and what it does. Right. So there is a part of the cortex. The cortex is this all-important outer layer of the brain. And it's a part of the cortex that controls movement. And it was really the first part of the cortex that was understood in any way at all.

It's kind of the beginning of modern neuroscience. A little more than 100 years ago in 1870 it was discovered. And what happens is there's a kind of a strip of tissue. And the traditional view is that each spot in it connects to a part of the body and controls movement, controls muscles in that part. So it's kind of a map, if you will, that controls movement. That's the general idea of the motor cortex. And how big is the motor cortex area of the brain? It's not as big as you might expect.

In humans especially where we have so much of the rest of the brain taken up by high-level cognitive functions, it's squeezed up a bit. It's a narrow strip. It's only a couple centimeters wide and maybe five times as long. Okay, so not very big. Maybe you can just walk us through this, Michael, so we understand, if I'm reaching for a cup of coffee or I've got some water, water in front of me. I'm reaching for this cup. What exactly is happening in my brain? Maybe you can

just map this out for us a little bit so we get an understanding of how this works. Right. So we know certainly there's a whole pattern of muscle activity that allows you to do that. That muscle activity ultimately is coordinated in your spinal cord, which has enormously rich, complicated networks in it. Many people don't realize the spinal cord is smarter than most animals out there. It's a very, the computation heavy part of the body, then the spinal cord is under direct control by the motor cortex. And so the motor cortex, in effect, is controlling this set of simpler algorithms in the spinal cord and giving somewhat higher level commands that allow your limbs to move. And exactly how the motor cortex works has been in some contention.

The simpler traditional ideas are clearly not 100% right. And so that's been the topic of very exciting ongoing research. Yeah, and we're going to talk about some of that research now. I want to turn to you, Evan. We've known about the motor cortex for a while. As a radiologist, what you do is you do scans and you look at people's brains. And you've found something interesting in some scans having to do with a motor cortex. Why don't you tell us about these findings?

That's right, John. We found it the motor cortex, which Michael has so eloquently described, has somewhat of a different organization than what science and medicine have believed for 90 years. We see that the motor cortex, in addition to containing these different areas controlling different parts of your body, it also seems to control this previously unknown set of areas, networked areas, strongly interconnected, that looks like it allows complex planning areas of your brain to influence, whole body actions. So, you know, as Michael described, for a long time we believed that in the motor cortex, there's this smooth progression as you get from sort of the top middle part of the

motor cortex to the bottom lateral side part of the motor cortex that controls one part of your body, then the other, then the next, then the next, moving from your toes and your feet to your arms and your hands to your face and your tongue. And that each of these really, regions acts kind of in isolation to control the movement of its particular body part that it cares about. But we found out that when we go and map individual human brains in great detail, this isn't quite true. So certainly, yes, there are these areas that control the feet and the hands and the face, but

in between these three known areas, we found three other unusually strongly interconnected regions. The face area and the hand area, they don't connect to each other. They don't act together very much. But these three other areas we found in between, they seem like they do strongly act together. And they act together not just in response to movements of specific body parts, but to many different types of movements, and especially to movements of your core body. And the other really interesting thing about them is they seem to be strongly connected to areas in prefrontal cortex that are responsible for planning and decision making. What we think of as the smartest areas of the brain, these areas that we think of as just dumb, motor, move your body part areas are strongly connected to these smart planning areas.

And finally, it seems like these areas correspond to regions that in the monkey brain are known to connect directly to internal organs like your stomach or your adrenal medulla. So this is sort of a complicated set of findings, but we think that this new system represents a circuit that enables whole body actions, not just isolated movements of your fingers, like if you're playing a piano or even if you're talking and you need to move your tongue in these very complicated ways. but we think about whole body actions like dancing or like sports. And this system allows these whole body actions to be strongly influenced by your plans and your goals. And the potential connection to these internal organs might allow changes in your adrenaline or your heart rate even before you start an action, sort of anticipatory changes. In some ways, that sort of sounds like good news, I suppose, for humans who plan things in advance. I want to ask a little bit more about the, scans in what you found. But first of all, Michael, I'm just wondering if you could respond. I mean,

how much does this upend what we've thought about the motor cortex previously? Well, that's a really good question. The motor cortex field, because it's so old, is in a sense fraught with a great deal of tradition. And the tradition is on a regular basis kind of bashed, and it seems to be toppling, and then it kind of recovers itself. And so every so often you find studies that show that the traditional view is not correct. And so, for example, a little more than 20 years ago, my own lab found evidence that the traditional map of muscles, so-called homunculus, the little body in the brain, is not correct, and that there's a great deal of intercoordination between muscles and a sort of rich, holistic approach to movement control. And so there's that. The traditional

map is clearly not correct, exactly how it's not correct and exactly what is correct. That's really up to discovery. And I think that this recent study is fantastic. It's amazing. And it really begins to show that the motor cortex is not just about controlling what are called skeleto movements or movements of your basic joints, but can also be involved in internal organs and internal body States and link to higher cognition. So this is really amazing. It does put a dent in the traditional view. I wish the traditional view had a little more dense in it. And this may well indeed be a dent. So Evan, talk about some of these involuntary movements, things like breathing, my heart pumping. What do we know about how that's mapped into the brain as opposed to the things?

that I'm planning to do are the things that I'm trying to do with my arms and fingers at any one time? Well, we don't know that much about how sort of these involuntary movements like breathing and heart rate are regulated. We think that we've, the traditional view has been that we think that these are regulated more by very low level systems, mostly in your brainstem, but it's always been a question in my mind, well, okay, if these are sort of just dumb areas of the brain that are regulating your heart rate and your breathing, how is it that when I'm thinking about things that I'm going to do? When I'm thinking about something that's going to be difficult or anxiety producing, I have to give a big talk in front of a big crowd tomorrow.

It's not even today. It's tomorrow. I'm thinking about giving this talk. And my heart rate accelerates. My breathing starts changing. I start sweating. Why is it that just our thoughts can cause these changes in our autonomic body systems? This is where I think we have to look to cortex. We have to look to these very smart areas of cortex and understand how our planning, not doing actions, but planning might be connected in more direct ways to our autonomic body functions. And I want to get to some phone calls now. We've got a lot of questions from our listeners, 844-724-8255.

Let's go to Jim, who is calling from California. Hi there, Jim. You're on Science Friday. Do you hear me okay? Sure can, Jim. Okay, good. No, I was wondering what the chemistry is there to motivate somebody. You know, when you make the conscious choice to do something,

what motivates you to do it, especially if there's like risk involved, or some other challenge of painting that might be that you have to overcome. What is that chemistry that motivates you past all those seemingly barriers there? It's an interesting question, Jim, thank you. I'll put you on hold so you can listen to our experts. I don't know, Michael or Evan, what do you think about this? I mean, if we're talking about planning, we're also talking about all sorts of motivations that people have to do various things.

I mean, I could take a, oh, go ahead. I was going to take a quick stab at it. Yeah. One of the wonderful things about the brain as people study it further is that there are a very large number of different networks that do different things yet all coordinate with each other. And so when you're talking about control of movement, that seems to be one network. You're talking about deciding, decision-making cognition that allows you to decide what is the right thing to do. That's perhaps another network. And yet there's a third system in the brain which involves motivation, emotional motivated states.

And so all three of those need to interact with each other in order to accomplish the kinds of things that the caller is talking about. Did you have a thought? I think Michael, I think Michael's exactly right here. And we've been thinking in our work, we've been thinking about this a lot because we've been trying to map out some of these big brain networks that seem to do these different sorts of things. And one of the things that we've observed is that these planning decision areas I've been talking about that have this surprising connection to motor cortex. We've been trying to look into where they get their inputs from. And as the caller might have guessed, they seem to have inputs from systems that provide, they have inputs from several different

systems. One of them seems to be systems that provide motivation. They get reward. information and they decide on the value of that reward and they project that value judgment backwards into this decision-making system and then another input to this decision-making system seems to be some of these networks that do very complicated cognition if you if you need to do math if you need to think through a series of logical steps this is the brain network that does that and this brain network also provides input to this decision-making system and then this decision-making system projects right backward into implementing these whole-body

actions in what we thought of as the motor cortex. So I think that the caller's instinct is very right that all of these different inputs are weighed and judged in these certain decision-making areas of the brain. We're talking about the brain-body connection, and this is Science Friday from WNYC Studios. And we'll get to some more of your phone calls in just a moment at 8.4. 74-8255. So Michael, in my other life, away from radio, I'm a yoga teacher. I've practiced yoga for years. And one of the things we talk about a lot in yoga is pro preception, you know, the sense that we can tell how our body's moving, where it is in space. It's something that's really different for everyone. I guess I'm wondering with what we know about the motor cortex, how it is that people sense where their body is and how their body's moving much differently from person to person. And not everyone knows exactly what it means to hold both arms parallel to the floor, for instance. How exactly does that work out in the motor cortex?

Right. Another super good question. The sense of your body configuration and body movement in space is partly involved with the motor cortex. There's a large number of other areas that are involved in that. And what you're talking about is sometimes called the body schema. So the body schema is the brain's essentially simulation or model that a picture that it builds for itself of what your body is doing, where your limbs are. And that body schema is very complex. It's not just sensors in your joints telling you where your arms are.

That's a very small part of it. Another part of it is vision. You see where your arms are. So vision has to connect to your sense of your joint sense. Another part of it is your motor commands. If you tell your arm to move to the right, well, it's probably somewhere on the right. And another part of it has to do with just general knowledge

that you've unconsciously learned about how your body is jointed and put together. So all of these things come together in this big complex mix in order to allow you to know intuitively where your body parts are, how they're moving. And that's something that is trainable, learnable. And so you're quite right. People who do yoga, people who do dance, train up on this and become really good at it, much better than people who aren't so well trained on it. And we have a little less than a minute left, but that's important, right?

This is something that's trainable. This is something that we can make work better in this connection between our brain and our body. Yes. It is trainable. I want to let our listeners know that we're talking with Dr. Michael Gratziano. He's a professor of psychology and neuroscience at the Princeton Neuroscience Institute in Princeton, New Jersey. And we're also talking with Dr. Evan Gordon, assistant professor of radiology at Washington University School of Medicine in St. Louis. We're talking about the connection between the brain and the body, some new research into the motor cortex, trying to figure out how exactly this stuff works.

We'll even be talking about some mindfulness techniques and taking a lot of your phone calls at 844, 7,000. 724-8255. That's 844 SciTalk. We'll be right back in just a minute. This is Science Friday. I'm John Dankowski in for Ira today. We're talking this hour about some of the connections between our brain and our body. We're talking with Dr. Evan Gordon and Dr. Michael Gratziano, and we're taking some of your phone calls. Let's go to Peter, who's calling from Florida. Go ahead, Peter. You're on Science Friday. Yeah, you know, three days ago was the anniversary of Nadia Cominici getting those perfect tens. So what I'm asking is, how long will it be before you can do to my motor cortex make me a great gymnast? You know what I mean? It's kind of like, remember the $6 million man or whatever? When can we do that with people? Yeah, it's a really good question.

I think something that a lot of people are thinking about as they listen to this conversation. Michael, what do you say to our caller? I think that, you know, when you're young, that's when your brain is most, changeable, most learnable, most plastic. And unfortunately, by the time we get older, I think that plasticity is at least reduced. But it's still there. You can actually, with intense training,

you can't actually improve skills. As for getting all the way up to the Nadia level of skill, I don't know, that's something you start very young. Well, and maybe, Evan, it's something that we can't exactly replicate an Olympic athlete later in our life. But it does speak to the idea, since we're talking about this being trainable, it is something that maybe we can all do just a little bit better.

Maybe not to get to the Olympics, but maybe just to stand in our two feet a little bit stronger. I agree. I think that when you start thinking about improving your motor function, improving your motor abilities, there's no substitute for you have to go out and practice because practicing, actually doing it, the act shapes your motor cortex and it refines it.

there is a question, could we help accelerate that shaping? Could we help you learn to do it faster? You know, there's amazing new brain stimulation techniques coming out, transcranial magnetic stimulation where you can activate the brain a little bit by magnetic fields. There's new techniques coming out where you can use ultrasound, like low intensity sound waves directed at your cortex to increase or decrease the activity of your brain. Could we maybe use some technologies like that to accelerate this learning process? We don't know how to do it now, but it's not a crazy idea. Let's get to another phone caller here.

Valentina is calling from Chicago. Valentina, go ahead. You're on Science Friday. Oh, Valentina is not there anymore. Michael has a question, actually, that's not too terribly dissimilar. So let's go to Michael in Albuquerque. Hi there, Michael. Hey, how you doing, John? Doing quite well. What's your question? My question is this. I am a stroke survivor from February of this year, and of course I had an estemic stroke on the right side that affected my left side, and you had the speech. I had the weakness on the left arm and the right leg.

And then my question is basically, what does that have to do with the repairing, like restoring your speech and restoring the use of your faculties once you have the stroke? how does the brain or the cortex repair itself to get back to normal? Great, great question. Evan, what can you tell them? That's a wonderful question. We don't know the exact mechanisms of this repair,

of how the brain is, the term is plastic. It can change its functional a little bit to compensate for large losses in functional areas. What we do know for stroke, motor stroke in particular, is that the way that the brain starts compensating for loss of function mirrors the original organization. So you may have experienced something where although you have lost, and many people experience this, although you have lost your hand function, maybe originally you lost the function of your entire arm, the first thing that starts coming back is maybe your shoulder function. and then maybe a little after that, your elbow function starts coming back. That's a common experience in people who have strokes and lose arm function. But often the recovery doesn't get all the way to the hand. They never quite recover hand function.

And we believe that the reason for that is because of the organization of the motor cortex. If you look at how it's organized, the shoulder is the farthest away from the hand, but closest to these new in-between areas that we found. It goes shoulder and then elbow and then wrist and the hand end. If you have a stroke that really destroys your hand function, it may have affected your wrist and your shoulder, but we think it's possible that these new in-between areas in the motor cortex may be able to start progressively taking over the function of the proximal,

the nearby lost areas so they can maybe first take over the function of the shoulder and then take over the function of the elbow. Unfortunately, they rarely get to take over the function of the hand. But the discovery of these new in-between areas gives us a chance to maybe try new therapies, new ways of actually solving the problems that people have post-stroke. Absolutely. Very interesting. Let's go to another phone call. We have Lynn, who is calling from Indiana. Hi there, Lynn. You're on Science Friday. Hi. My question is, my father recently passed away, and he suffered from Alzheimer's at the end of his life. And as I listen to you, one of the things that I'm thinking of is what we noticed was from early on that actually it was his motor things went down as much, but the common therapy right now concentrates on their higher level skills, you know, their memory and things like that.

But I'm wondering that with this knowledge that you have, that maybe that's what we should be looking at, because I can also tell you that the more active my dad was, the better the rest of his skills of his brain work. So I'm wondering how this could apply to Alzheimer's research. It's a really good question, Lynn, and I'm sorry to hear about your father. Michael, what can you tell Lynn? Thank you. I think probably actually Evan would know way more about this as a neurologist. Yeah, Evan. So absolutely. It is a really good question. And of course, the reason that, you know this,

the reason that they were focusing so much with your father on focusing on these cognitive skills is that in Alzheimer's, those are most commonly lost. The areas that are first affected in Alzheimer's are far away from the motor cortex. They're especially in areas having to do with memory and the sense of time in the sense of yourself and also the sense of navigation. These, they're not very related to motor cortex. They're not very strongly connected to the motor cortex, but there is a lot of variability in something like Alzheimer's. And even while most people may have this really primary memory deficit

where their motor function is relatively spared for a long time, that's not the case for everyone. And certainly, as you experienced, there are individual cases where motor cortex may be degrading, as fast as the cognitive function. Now, your idea about if we can help recover the motor function, maybe it can help recover the cognitive function, that is, it's a great idea.

It's something that's intuitive to us, because I think we all sort of understand how, when we are active, it can help us think better. It helps us regulate our emotions better. It helps us concentrate better. This is a well-known phenomenon. And I think that these sets of circuits that we've identified here is a potential mechanism, how this may be happening. As you engage your body in motion, there may be feedback mechanisms back to these higher level cognitive areas that allow them to activate better, to engage better.

And while they probably wouldn't be slowing the progress of Alzheimer's, which is a very difficult problem that is not solved, it may very well be that physical activity may help for a little while engage your brain enough that it can overcome the deficits that the disease is causing. It's so interesting. And again, Lynn, thank you so much for your question. Michael, I want to get back to something that you talked about earlier. There's this kind of foundational concept in neuroscience called the homunculus. Maybe you can just describe exactly what this is and why it's become so prevalent in our understanding of the brain. Right. So the term, the homunculus, was introduced by the neurosurgeon Penfield in the 1930s. And he's the one who mapped the motor cortex

in humans. He didn't discover it. It had been discovered 70 years before his time, but he mapped it thoroughly in humans, and he noted this apparent map of muscles that if you drew it on a piece paper looked a bit like a distorted body with really big hands and a really big face. You know, the parts of the body that are controlled in finer detail have greater representation in the cortex. And so he called it the homunculus. And that was a very clever bit of PR, and that term has stuck. And now everyone, even non-neuriscientists, have heard of the homunculus. And so that's kind of the basis of how people have thought about the motor cortex. And of course, it's a little bit tongue and cheek because there's also a widely mocked, let's say a straw man view

of the brain the way people function is that there's a little man in your head that makes you move. And the reason why that makes so little sense is because what makes the little man move, does he have a little man in his head too? And so the homunculus concept is in some sense quite funny. But for the motor cortex, it made a great deal of sense for many, many decades. the homunculus is just much more complicated than a simple map of the body, it turns out. Yeah, it's sort of a funny idea to think about. It's also funny looking. It's like a little goblin with huge hands. If you see it embodied a big tongue and mouth and big ears, it's supposed to represent how much brain space is being used for the different body functions.

So, Michael, is this not true anymore? I mean, do we not believe in this homunculus model at this point? Well, the basics that you just described are absolutely true. It's just that in the motor cortex, it was once thought that every muscle had a little spot in cortex. And if you poked that spot, it would make that muscle twitch. And that turns out not to be true. The cortex basically learns really rich coordinated interconnections between muscles and body parts and helps coordinate movement. And, you know, we have found, for example,

you can poke a spot in the motor cortex and cause a behavior as complex as the hand closes into a grip. The grip moves to your mouth and your mouth opens. All of those things happening in coordination because the network in the motor cortex has learned that kind of rich coordination. So what's that, what's in debate is exactly how this is implemented in the motor cortex. But there's no doubt that different body parts have different amounts of representation in the brain. That basic idea is absolutely correct. This is science fraud. from WNYC Studios.

And we want to get to some more phone calls about the brain-body connection. Jennifer is calling from Durham. Go ahead, Jennifer. You're on Science Friday. Hey, thanks for taking my call. So I am a congenital amputee. I was born with a limb difference,

and my husband and I owned a small prosthetic company in Durham, and I spent a lot of my time visiting folks that are new to amputation in the hospital following their surgery and just working with people through the rehabilitation process. And so a lot of people that experience amputation experience something called phantom limb sensation or phantom limb pain, essentially, even though that part of the limb that is, it's no longer there, but you are still feeling like it's there.

And it could just be a feeling of, like, twitching in a foot that's not there or severe pain. And not everybody gets it. Not everybody experiences that. It sort of depends on the circumstances around your liver. loss. And so when I talk to people about that, I usually say I frame it as in like your brain has a map of your body. And now that that part of your body is gone, your brain, it takes a while to really adjust to that and for your brain to understand that. And that's what you are experiencing is a misfiring of your brain. And, you know, as you begin the prosthetic rehabilitation, you know,

that also helps mapping the new map of your brain. And right now, prosthetics are typically not, you know, they're not directly integrated with your nervous system. That's certainly like the future of prosthetics. But all the things that you're talking about, proprioception, you know, balance, it takes practice. And so people find it's very difficult at first to use a prosthesis, but throughout the process, that brain is reforming, right?

The map is reforming. And that's why people eventually progress and feel like, oh, this prosthesis is like part of my body now. I just thought it was something to bring up. I think it's a very important thing to bring up. I'm so glad you did, Jennifer. And Evan, I don't know if you want to build a bit on what Jennifer had to say. I think that Jennifer's describing it extremely well. This is exactly the right way to think about it.

When you have an amputation, you have a part of your sensory cortex, which is organized a lot like the motor cortex, where it has different parts of it that are mapped to different parts of your physical body. That part of your brain has completely lost its input. What is it going to do? Neurons don't know what to do when they lose their inputs. They start firing randomly. Everything that they were expecting is messed up. The neurons themselves, they're organized in the very complex recurrent network.

Different neurons are pointing to each other. They've all lost their inputs. They're all pointing randomly at a different. other they're causing random firing all over the place it's it's it's it's complete confusion and that can be easily easily interpreted as pain and the the that representation of that missing body part needs to be what's called it needs to be remapped it and that is exactly what this rehabilitation process that Jennifer is talking about is intended to do it's intended to make this

remapping process go as fast as possible you have this part of your brain that was mapped to this missing part of your body. Can we try to remap that part of your brain to something else that is intact that is still getting input? And so that this input doesn't come, that there's not this lack of input in this crazy activation, which is very unpleasant. Interesting stuff. There's so much more to talk about and so many more questions, but we've just about run out of time. I want to thank Dr. Evan Gordon, Assistant Professor of Radiology at Washington University School of Medicine in St. Louis. Thank you so much, Evan. Thank you so much, John. I loved being on here. And Dr. Michael Gratziano, a professor of psychology and neuroscience at the Princeton Neuroscience Institute in Princeton, New Jersey. Thank you so much, doctor. Thank you.

And before we go this hour, we could not let this Friday pass without marking the extraordinary life and career of jazz singer Tony Bennett, who died this morning in New York at the age of 96. Now, among his many hits was this very lush 1965 recording of a song that, that became synonymous with the Apollo missions. Now, Tony's moon mission, as you'll hear, is just a little bit slower than that of his fellow traveler, Frank Sinatra. Fly and let me play the star. Rest and peace, Tony. Now, we had helped this week from a lot of folks, including Experiences Manager Diana Montana,

controller Beth Rami, grants manager Jordan Smudjik, and Jason Rosenberg, and audio engineers Lisa Gosselin and Kevin Wolfe. BJ Leatherman composed our theme music. If you missed any part of this program or you'd like to hear it again, subscribe to our podcasts. You can ask your smart speaker to play Science Friday. You can also email us to. The address is SciFri at ScienceFri.com.

I'm John Dankoski. Thanks for joining us.