Speaker 1: If you take a look at a brain, how can
Speaker 1: you tell immediately if it belongs to a piano player
Speaker 1: or a violinist? How can a dog learn to walk
Speaker 1: on its rear legs like a human? And what does
Speaker 1: this have to do with how you become an expert
Speaker 1: at something? Or what would happen if Venus and Serena
Speaker 1: Williams had a hypothetical brother, Fred who hated tennis? And
Speaker 1: how do governments respond to change just like brains do?
Speaker 1: And finally, why am I so optimistic about the brains
Speaker 1: of digital natives. Welcome to the inner Cosmos with me
Speaker 1: David Eagleman. I'm a neuroscientist and author at Stanford and
Speaker 1: in these episodes we sail deeply into our three pound
Speaker 1: universe to understand why and how our lives look.
Speaker 2: The way they do.
Speaker 1: Today's episode is about brain plasticity, which is the ability
Speaker 1: of the brain to change and adapt throughout your life.
Speaker 1: The word plasticity comes from the word plastic, which is
Speaker 1: a material that you can mold into any shape and
Speaker 1: then it holds onto that shape. And that is what
Speaker 1: is impressive about brains. You can expose them to any
Speaker 1: kind of situation or experience, and they hold on to
Speaker 1: the change. The vast forest of neurons in your head,
Speaker 1: These connections change their strength, and sometimes they unplug and
Speaker 1: they seek around and they replug in somewhere else. It's
Speaker 1: a living forest of eighty six billion neurons in your head,
Speaker 1: and this constant reconfiguration, this is how you learn and remember.
Speaker 1: The interesting part I want to address today is exactly
Speaker 1: when these changes in the brain happened, because it's not
Speaker 1: all the time. Most of the stuff that happens in
Speaker 1: your life makes no change at all to your brain.
Speaker 1: So what's the difference between the stuff that sticks and
Speaker 1: the stuff that doesn't. So let's start today in Hungary
Speaker 1: with an educational psychologist named Laslow Polgar. The thing about
Speaker 1: Laslow is that he loves chess, and he's written some
Speaker 1: well known chess books. But that's not the super interesting
Speaker 1: thing about him. The super interesting thing is that he
Speaker 1: got very interested in the theory of child rearing and
Speaker 1: he believed quote, geniuses are made, not born. So he
Speaker 1: started preparing himself for fatherhood even before he had a spouse,
Speaker 1: and he read the biographies of four hundred famous intellectuals
Speaker 1: like Socrates and Einstein, and he noted that what they
Speaker 1: all had in common is they started their intellectual pursuits
Speaker 1: at a young age and they studied intensively. So he
Speaker 1: concluded from this research the idea that he could, with
Speaker 1: the right effort, turn his future children into geniuses in
Speaker 1: a particular area which he and his wife could think
Speaker 1: about and pick. So they considered various domains, but they
Speaker 1: chose chess in part because the success of these children
Speaker 1: could be easily measurable with chess. So he and his
Speaker 1: wife had three daughters together, Susan, Sophia and Judete, and
Speaker 1: he made the move, which was unusual in Hungary at
Speaker 1: the time, to homeschool them, and he taught them German
Speaker 1: and English and Russian and high level math, but he
Speaker 1: primarily taught them chess from the moment that they were
Speaker 1: big enough to play with the pieces.
Speaker 2: So what was the result.
Speaker 1: By the time his eldest daughter, Susan turned fifteen years old,
Speaker 1: she was the top ranked chess player in the world.
Speaker 1: In nineteen teen eighty six, she qualified for the men's
Speaker 1: World Championship, which was a first time achievement for a female,
Speaker 1: and within five years she had earned the men's Grand
Speaker 1: Master title and then in the middle of Susan's astounding accomplishments,
Speaker 1: Her fourteen year old middle sister, Sophia, achieved fame for
Speaker 1: her sack of Rome, which was her stunning victory at
Speaker 1: a tournament in Italy, which ranked as one of the
Speaker 1: strongest performances ever by a fourteen year old. Sofia went
Speaker 1: on to become an international master and a woman grand master.
Speaker 2: And then there was.
Speaker 1: The youngest sister, Judite, who is widely considered the best
Speaker 1: female chess player on record. She achieved grand master status
Speaker 1: at the tender age of fifteen years and four months,
Speaker 1: and she remains the only woman on the World Chess
Speaker 1: Federation's Top one hundred list, and for a while she
Speaker 1: held a position in the top ten. So what accounts
Speaker 1: for their success, Well, their parents trained the girls every
Speaker 1: single day. They didn't just expose them to chess, they
Speaker 1: fed them on chess.
Speaker 2: The girls received hugs.
Speaker 1: And stern looks and approval and attention based on their
Speaker 1: chess performance, and as a result, their brains came to
Speaker 1: have a great deal of circuitry devoted to chess. Now,
Speaker 1: we've seen in other episodes how the brain is always
Speaker 1: rewriting itself in response to its inputs. But the fact
Speaker 1: is that not all information streaming into the pipelines is
Speaker 1: equally important. How brains adjust themselves has everything to do
Speaker 1: with what you're spending your time on, and that's why
Speaker 1: the Polgar sisters became biological chess machines. And it's the
Speaker 1: same thing with your brain. It'll reconfigure to whatever you're doing.
Speaker 1: So if you decide to make a career change to ornithology,
Speaker 1: the study of birds, more of your neural resources will
Speaker 1: become devoted towards learning the subtle differences between birds, like
Speaker 1: their wing shape, or their breast coloration, or their beak size,
Speaker 1: while maybe previously your neural representation of birds with something
Speaker 1: more crude, like is that a birder and airplane. So
Speaker 1: let's dive in to unpack how the brain makes changes
Speaker 1: and when it doesn't, which will tell us everything we
Speaker 1: need to know about how to make changes stick in
Speaker 1: your own brain. There's a great story about the violinist
Speaker 1: Yetsak Pearlman after one of his concerts and admiring concertgoer
Speaker 1: said to him, I would give my life to play
Speaker 1: like that, and Pearlman said, I did, Now what did
Speaker 1: he mean? Well, every morning, Pearlman drags himself out of
Speaker 1: bed at five point fifteen. He takes a shower and batakfast,
Speaker 1: and then digs into his four and a half hour
Speaker 1: morning practice. He then takes a lunch and an exercise session,
Speaker 1: and then launches his afternoon practice for another four and
Speaker 1: a half hours. He does this every day of the year,
Speaker 1: except for concert days, when he does only the morning
Speaker 1: practice session. And you know what, Brain circuitry comes to
Speaker 1: reflect what you do. So the cortex of Jasah Pearlman,
Speaker 1: or any highly trained musician changes through time into something different.
Speaker 1: And this isn't a metaphorical claim. You can see this
Speaker 1: with brain imaging, even with an untrained eye.
Speaker 2: Let me tell you how.
Speaker 1: If you look at the strip of brain right underneath
Speaker 1: where you wear headphones, that's an area called the motor cortex,
Speaker 1: and that's what directs your body how to move all
Speaker 1: of its six hundred exquisitely beautiful muscles. Now, if you
Speaker 1: zoom in on a region of the cortex involved in
Speaker 1: hand movement, you'll find something amazing, which is that musicians
Speaker 1: have a little puckered shape on their cortex where non
Speaker 1: musicians don't. So think of it like an extra wrinkle
Speaker 1: on the wrinkly outer bit of the brain, the cortex.
Speaker 2: Why do the musicians have this.
Speaker 1: It's because they use the muscles of their hands in
Speaker 1: an extraordinarily detailed way, much more so than non musicians,
Speaker 1: so their.
Speaker 2: Brains devote more real estate to that task.
Speaker 1: The thousands of hours of practice on the instrument physically
Speaker 1: molds their brains. And by the way, this is wildly specific.
Speaker 1: So imagine that you compare the brain of a violinist
Speaker 1: like Pearlman to the brain of a pianist like Vladimir Ashkenazi.
Speaker 1: What they both have in common is a deep dedication
Speaker 1: to their craft and countless hours of practice, and yet
Speaker 1: their brains look sufficiently different that you can easily see
Speaker 1: which brain belongs to whom. And that's because string players
Speaker 1: like Pearlman show that extra wrinkle mostly on one side
Speaker 1: and one hemisphere, because his left fingers are doing all
Speaker 1: the detailed work while the right hand mostly just runs
Speaker 1: the bow over the strings. In contrast, a pianist like
Speaker 1: Ashkenazi has that extra wrinkle in both hemispheres because both
Speaker 1: of his hands are performing meticulous patterns on the ivories.
Speaker 1: So simply by looking at the brain which used to
Speaker 1: be done in autopsy, but now you can do with
Speaker 1: a brain scan. You can tell what kind of musician
Speaker 1: you have in the scanner. You can discern this just
Speaker 1: by looking at the wrinkly bits on the motor cortex.
Speaker 2: And we can read even more from the brain's patterns.
Speaker 1: It represents not only that a hand is doing less
Speaker 1: or more, but sometimes what what in particular it's doing.
Speaker 1: So let's say you get a job at an assembly
Speaker 1: line and you're randomly assigned to one of two jobs.
Speaker 1: Either you put little marbles into jars, or your job
Speaker 1: is to screw the jar lid shut. Okay, so both
Speaker 1: jobs use your right hand, but the first requires fine
Speaker 1: use of your fingertips, while screwing the lid on makes
Speaker 1: use of your wrist and forearm. So if you're the
Speaker 1: jar filler, the real estate in your cortex that represents
Speaker 1: your fingers will increase, and this is at the expense
Speaker 1: of the real estate devoted to your wrists and forearms.
Speaker 1: If you are the lid turner, the opposite happens. You
Speaker 1: get more representation for your wrist and forearm and less
Speaker 1: for the detailed movement of your fingers. So in this way,
Speaker 1: what you do over and over becomes reflected in the
Speaker 1: structure of your brain, and these changes involve more than
Speaker 1: the motor cortex.
Speaker 2: For example, if.
Speaker 1: You spend months learning to read Braille, the bit of
Speaker 1: your cortex that represents touch from the index finger that
Speaker 1: will grow. If you take up juggling as an adult,
Speaker 1: the visual areas of your brain involved in that they increase.
Speaker 1: This is because brains reflect not simply the outside world,
Speaker 1: but more specifically your outside world, and this is what
Speaker 1: underlies getting good at something. Professional tennis players like Serena
Speaker 1: and Venus Williams they spend years training so that the
Speaker 1: right moves will come automatically in the heat of the game. Step, pivot, backhand, charge, fallback, aim, smash.
Speaker 2: They train for.
Speaker 1: Thousands of hours to burn the moves down into the
Speaker 1: unconscious circuitry of the brain. They craft their brains into
Speaker 1: overtrained machinery. He might have heard of the ten thousand
Speaker 1: hour rule, which suggests that you need to practice a
Speaker 1: skill for that many hours to become an expert, whether
Speaker 1: this is surfboarding or spelunking, or saxophone playing or whatever.
Speaker 1: Although we can't quantify the exact number of hours, the
Speaker 1: general idea is correct. You need massive amounts of repetition
Speaker 1: to dig the subway maps of the brain. There's a
Speaker 1: guy that I mentioned in an earlier episode. His name
Speaker 1: is Destin Sandlin, and he made a video where he
Speaker 1: tries to ride a bike that someone gave him with
Speaker 1: reversed steering, so when you push the handlebars to the left,
Speaker 1: the wheel turns to the right and vice versa. This
Speaker 1: is a super difficult thing to learn how to ride.
Speaker 1: So what he did is he spent every day working
Speaker 1: on this and trying it out, and he crashed and crashed,
Speaker 1: but eventually he got it. But the point I want
Speaker 1: to make here is that you know, he's an engineer,
Speaker 1: and it only took him a few seconds to cognitively
Speaker 1: understand how the bike worked, but that proved insufficient to
Speaker 1: ride it. He needed to invest weeks and weeks of practice.
Speaker 2: Hence the ten thousand hour rule.
Speaker 1: And this dynamic changing of the brain happens from intensive
Speaker 1: physical practice that you do, whether that's swimming or playing
Speaker 1: the harmonica, or swinging a tennis racket or using a
Speaker 1: rake or whatever. But these measurable brain changes, they don't
Speaker 1: just apply to the physical they apply to the mental also,
Speaker 1: so for example, when medical students study for their final
Speaker 1: exams over the course of three months, particular areas of
Speaker 1: their cortex changed so much that you can see this
Speaker 1: on brain scans with the naked eye. And you see
Speaker 1: something similar if you teach a person how to read
Speaker 1: backward through a mirror. And here's another example. Areas of
Speaker 1: the brain that are involved in spatial navigation are visibly
Speaker 1: different in London taxi drivers from the rest of the population.
Speaker 1: In each hemisphere, the taxi drivers have an enlarged region
Speaker 1: part of the hippocampus, which is an area involved in
Speaker 1: your internal maps of the outside world. So what you
Speaker 1: spend your time on changes your brain. You are more
Speaker 1: than what you eat. You become the information you digest.
Speaker 1: And this is how the Polgar sisters were able to
Speaker 1: blossom into world champion chess players. It's not because some
Speaker 1: gene codes for skill at chess. It's because they practiced
Speaker 1: over and over chiseling pathways in their brains to encode
Speaker 1: the powers and patterns of knights and rooks and bishops
Speaker 1: and ponds and kings and queens. So brains come to
Speaker 1: reflect their world.
Speaker 2: But how does this happen? Exactly. Well, let's see the.
Speaker 1: Answer by zooming in on a weird illusion that most
Speaker 1: of us have experienced, the phantom phone vibration. I recently
Speaker 1: saw a meme online. It was a picture of a
Speaker 1: human brain with the title that reads, Hey, I think
Speaker 1: your phone just buzzed in your pocket, and then on
Speaker 1: the bottom it reads, just kidding. Your phone isn't even
Speaker 1: in your pocket, you moron. Now, the phantom cell phone
Speaker 1: vibration is a menace that is unique to the twenty
Speaker 1: first century. It happens because of a momentary spasm or
Speaker 1: quivering or shaking, or a touch on your leg, And
Speaker 1: as long as the frequency and the duration of that
Speaker 1: feeling is vaguely similar to that made by your phone,
Speaker 1: your brain decides on your behalf, that's something interesting is
Speaker 1: happening with your phone. So thirty years ago, if you
Speaker 1: had noticed a leg twitch, you would have interpreted the
Speaker 1: feeling as a fly landing on you, or a movement
Speaker 1: of your clothing, or something accidentally brushing past you. So
Speaker 1: why does your interpretation differ from one generation to the next,
Speaker 1: Because your phone now serves as the optimal explanation for
Speaker 1: a whole range of twitchy feelings. So here's how to
Speaker 1: understand what's happening there in the brain. Think of a
Speaker 1: mountainous landscape. Now, picture a lake somewhere there that's encircled
Speaker 1: by mountains. For a rain drop to end up in
Speaker 1: that lake, it doesn't need to fall from the sky
Speaker 1: and land directly in the water. Instead, it only needs
Speaker 1: to hit the surrounding hillsides. It can land on the
Speaker 1: northern slope or the southern, or the eastern incline or
Speaker 1: the western and in any case it's gonna slide down into
Speaker 1: the lake. So the lake is what's known as an
Speaker 1: attractor state. Anything nearby will flow to that spot, and
Speaker 1: you have lots of such attractor states in your brain.
Speaker 1: So the feeling on your thigh doesn't have to be
Speaker 1: a buzzing phone.
Speaker 2: It can be a slight shift.
Speaker 1: Of your genes or a twitch of your thigh muscle,
Speaker 1: or an itch or graze past the sofa.
Speaker 2: As long as the feeling is close, the signals.
Speaker 1: Slide down the landscape to their attractor state, and then
Speaker 1: you reach to check for an important message. The landscape
Speaker 1: gets formed by what is important in your world. For
Speaker 1: another example, think about the way we interpret the sounds
Speaker 1: of language. It feels natural to you that you can
Speaker 1: understand the sounds of your native language, but foreign languages
Speaker 1: often have really close sounds that you can't hear the
Speaker 1: difference between.
Speaker 2: Like ooh and eh. But why why can you not
Speaker 2: hear those?
Speaker 1: As it turns out, there is something different about the
Speaker 1: brains of the people who speak those languages. But they
Speaker 1: weren't born that way, and neither were you. If you
Speaker 1: look at the space of all the possible sounds that
Speaker 1: humans can make with our mouths, it makes a relatively
Speaker 1: smooth continuum. You can kind of make any sound. But
Speaker 1: despite this, you learn from experience that specific sounds mean
Speaker 1: the same thing, whether they're uttered by your dad, or
Speaker 1: your babysitter or your teacher. Your brain figures out that
Speaker 1: a drawn out E and eclip to e both belong
Speaker 1: to the E category, or maybe your friend from Texas
Speaker 1: says a or whatever. But your experience teaches you that
Speaker 1: all the speakers mean the same sound, regardless of exactly
Speaker 1: how they're pronouncing it, and so your neural networks carve
Speaker 1: out a landscape in which all these sounds roll down
Speaker 1: the hillsides to the same interpretation. There's a lake in
Speaker 1: your brain that represents E, and all the inputs from
Speaker 1: all around end up in that lake and in neighboring valleys,
Speaker 1: you gather up sounds that are equivalent to A or
Speaker 1: I or O and so on. So with time, your
Speaker 1: landscape looks different from someone who's grown up in another
Speaker 1: language and who needs to distinguish the smooth continuum of
Speaker 1: sounds differently than you do. To think about an example
Speaker 1: of this, imagine a baby born in Japan call him Hyato,
Speaker 1: and a baby born in America call him William. From
Speaker 1: their brain's point of view, there is nothing different about them.
Speaker 1: But in Osaka, Hayato hears Japanese all around him.
Speaker 2: From day one.
Speaker 1: In Palo Alto, William hears the tones of English, where
Speaker 1: different sounds carry meaning. An example of what these two
Speaker 1: babies hear differently is the distinction between the.
Speaker 2: R and L sounds.
Speaker 1: So in English, these carry information like the word right
Speaker 1: versus light or raw versus law, But in Japanese there's
Speaker 1: no distinction between these two sounds. So as a result,
Speaker 1: William's internal landscape builds a mountain range between his interpretation
Speaker 1: of R and L, such that the difference between these
Speaker 1: two sounds is perceptually clear. In Hyato's brain, the landscape
Speaker 1: develops into a big valley, so that both R and
Speaker 1: L flow into a single lake because they have an
Speaker 1: identical interpretation. So as a result, Hyato can't hear the
Speaker 1: difference between those two sounds. Now, obviously, the children's brains
Speaker 1: were not born this way. Had William's pregnant mother moved
Speaker 1: to Osaka and Hyato's pregnant mother to Palo Alto, the
Speaker 1: boys would have had no trouble in becoming fluent speakers
Speaker 1: and listeners in their new language.
Speaker 2: As opposed to a genetic issue.
Speaker 1: Their neural landscapes are carved by what is relevant in
Speaker 1: their immediate environment. And what's fascinating is that you can
Speaker 1: see this carving happening even before the children learn how
Speaker 1: to speak. For example, make a continuous R sound and
Speaker 1: then switch it over to L. So L, now, how
Speaker 1: can you tell if an infant here's that change?
Speaker 2: So it turns out the trick.
Speaker 1: To the experiment is this, Infants will suck faster at
Speaker 1: the nipple when they detect a chain. When they hear
Speaker 1: a change from one sound to another sound, they go
Speaker 1: from suck suck suck to suck suck, suck, suck. So
Speaker 1: at the age of six months, both Hyato and William
Speaker 1: will both suck faster when the R changes to L.
Speaker 1: But by twelve months, Hyato stops detecting the change. R
Speaker 1: and L sound the same to him. Both sounds are
Speaker 1: sliding down into the same valley. Hyato's brain has lost
Speaker 1: the ability to distinguish these sounds, while William's brain, having
Speaker 1: passively listened to his parents speak tens of thousands of
Speaker 1: English words, has learned that there's information carried in the
Speaker 1: difference between these two sounds. Hyato's brain, meanwhile, has picked
Speaker 1: up on other sound distinctions, which to William would be indistinguishable.
Speaker 1: So your auditory system begins universally and then wires itself
Speaker 1: to maximize the distinction unique to your language, depending on
Speaker 1: where on the planet you happened to stick your head
Speaker 1: out of the womb. And similarly, the buzzing phone isn't
Speaker 1: something you were born to detect. Instead, it's high relevance
Speaker 1: carves your neural landscape such that you have a broad
Speaker 1: catch all for neighboring sensations, all of which you will
Speaker 1: interpret as a buzzing cell phone in your pocket. Like kyata.
Speaker 1: With the R and the L, you combine the twitches
Speaker 1: and vibrations and quiverings into a single interpretation of what
Speaker 1: just happened. Now, from what we've seen so far, we
Speaker 1: might think that repetition is the key to molding the
Speaker 1: circuitry in your brain. But in fact, there's a deeper
Speaker 1: principle at work. So now we're going to talk about relevance.
Speaker 1: There's an old joke that goes, how many psychiatrists does
Speaker 1: it take to change a light bulb? And the answer
Speaker 1: is only one, But the light bulb has to want
Speaker 1: to change. Now, if you listen to episode two, you
Speaker 1: may remember a dog that I talked about named Faith.
Speaker 1: She is very memorable because Faith was born with out
Speaker 1: front legs and she figured out how to walk by
Speaker 1: pedaly on her hind legs, sort of like a human.
Speaker 2: Now.
Speaker 1: When I told her story in episode two, I said
Speaker 1: it as though her brain had just figured out her
Speaker 1: unusual body plan. But we can now dig a little
Speaker 1: deeper for a hidden bone. Was there something special about Faith?
Speaker 1: Could any dog have pulled us off? And if they
Speaker 1: could have, why don't all dogs walk by?
Speaker 2: Peeda Ly?
Speaker 1: Faith's rewritten maps were all about relevance to her life.
Speaker 1: Her brain was shaped by her goals. Faith needed to
Speaker 1: get to her food. That required a solution. It wasn't
Speaker 1: going to be the same one that was used by
Speaker 1: her four legged siblings. She had to derive a novel solution,
Speaker 1: so her brain tried out various strategies until it found
Speaker 1: when that worked balancing on her two back legs and
Speaker 1: lurching forward step after step. This allowed her to get
Speaker 1: what she needed, and after a while, she became good
Speaker 1: at this method of locomotion. In the absence of finding
Speaker 1: an answer to her challenge, she would have starved and died.
Speaker 1: Her drive for survival allowed the flexible circuitry in her
Speaker 1: brain to try out a bunch of hypotheses and solve
Speaker 1: the problem getting her to food and shelter and loved ones.
Speaker 2: So goals matter.
Speaker 1: A brain's goals play a critical role in how and
Speaker 1: when it changes. For the Polgar sisters, achieving their expertise
Speaker 1: depended on a desire to achieve their expertise. Same with
Speaker 1: Yitzak Pearlman or Vladimir Ashkenazi. Imagine for a moment that
Speaker 1: Serena and Venus Williams had a brother, Fred, and that
Speaker 1: their parents had put a tennis racket in Fred's hands
Speaker 1: and forced him to go through all the years of
Speaker 1: practicing that his sisters went through. But imagine that he
Speaker 1: found tennis repulsive. He never got good feedback from his
Speaker 1: classmates about his performances, and he didn't win any contests,
Speaker 1: and his elders didn't lavish him with praise. The result
Speaker 1: of all that practice would be nothing. Fred's brain would
Speaker 1: show little reorganization. Although his body was going through the
Speaker 1: same motions as his sisters, the motions would be misaligned
Speaker 1: with his internal incentives. So this is easily shown in
Speaker 1: the laboratory. So imagine an experiment in which someone is
Speaker 1: tapping out Morris code on your foot while someone else
Speaker 1: totally separately is playing a sequence of sounds.
Speaker 2: Now, if the.
Speaker 1: Task is that you can win cash for decoding the
Speaker 1: message on your foot, then the brain regions involved in
Speaker 1: touch to that part of your body will develop higher resolution.
Speaker 1: The regions involved in your hearing won't change, even though
Speaker 1: that brain area is also receiving stimulation. Now imagine the
Speaker 1: reverse game. Now, answering questions about subtle differences between the
Speaker 1: sounds earns the cash while attending to your foot doesn't
Speaker 1: yield anything. Now we'll see changes in the auditory cortex
Speaker 1: where you're doing the hearing, but the touch in your
Speaker 1: somatosensory cortex won't change. The inputs from the world are
Speaker 1: exactly the same in both cases. But what changes in
Speaker 1: your brain depends on what is rewarded. And this is
Speaker 1: why Fred Williams gets no better on the tennis court.
Speaker 1: He derives no reward from it. In his brain, just
Speaker 1: like in yours, the maps of the neural territory reflect
Speaker 1: to the strategies that have won positive feedback. Now this
Speaker 1: kind of understanding about motivation and relevance leading to change
Speaker 1: in the brain. This understanding opens new pathways for recovery
Speaker 1: from brain damage. So imagine that a friend of yours
Speaker 1: suffers a stroke. That damage is part of her motor cortex,
Speaker 1: and as a result, one of her arms becomes mostly paralyzed.
Speaker 1: So after trying many times to use her weakened arm,
Speaker 1: she gets frustrated and just uses her good arm to
Speaker 1: accomplish all the necessary tasks in her daily routine. This
Speaker 1: is a typical scenario, and her weak arm becomes only
Speaker 1: weaker because she's never choosing to use it. Now, the
Speaker 1: lessons of brain plasticity that we've been talking about offer
Speaker 1: a solution that is counterintuitive. The solution is known as
Speaker 1: constraint therapy. You strap down her good arm so that
Speaker 1: she can't use it, and that forces her to employ
Speaker 1: the weak arm. Now, this simple method retrains the damaged
Speaker 1: cortex by forcing use of the bad arm and cleverly
Speaker 1: taking advantage of these neural mechanisms underlying desire and reward.
Speaker 1: Because she has inherent motivation to get the sandwich to
Speaker 1: her mouth, or to turn the key in her front door,
Speaker 1: or to raise the cell phone to her ear, and
Speaker 1: to perform all the other actions that underlie a dignified,
Speaker 1: self sufficient life. So while constraint therapy starts off as frustrating,
Speaker 1: the approach proves to be the best medicine because it
Speaker 1: forces the brain to try new strategies, and the reward
Speaker 1: locks in the methods that work. It seems paradoxical that
Speaker 1: the solution of the problem is to make things worse,
Speaker 1: but that's precisely what solves. So let's return to faith
Speaker 1: the dog. Are all dogs able to walk on their
Speaker 1: back legs? Sure, but most dogs will never have the
Speaker 1: reason or motivation to attempt it, and certainly no reason
Speaker 1: to master it. And that's why Faith became famous, not
Speaker 1: because she's the only dog in the world who could
Speaker 1: do it, but because she's the only one who made
Speaker 1: it happen. You may know that some blind people learn
Speaker 1: how to navigate using echolocation. They make sounds with their
Speaker 1: mouth and they listen for the echo to give them information.
Speaker 1: But it turns out that people with perfectly normal vision
Speaker 1: can learn how to echo locate. Also, the issue is
Speaker 1: just that most cited people simply are insufficiently motivated to
Speaker 1: pour the hours and hours into redefining their neural territory. Now,
Speaker 1: reward is a powerful way to rewire the brain, but happily,
Speaker 1: your brain doesn't require cookies or cash. More generally, change
Speaker 1: is tied to anything that's relevant to your goals. If
Speaker 1: you're in the far North and you need to learn
Speaker 1: about ice fishing and different types of snow, that's what
Speaker 1: your brain will come to encode. If instead your equatorial
Speaker 1: and you need to learn which snakes to avoid and
Speaker 1: which mushrooms to eat, your brain will devote its resources accordingly.
Speaker 1: Using relevance as it's north star, the brain flexibly picks
Speaker 1: up on important details. It's billions of neurons serve as
Speaker 1: a colossal canvas for painting the world that we happen
Speaker 1: to find ourselves in, and with it we develop expertise
Speaker 1: and whatever has relevance to us, whether that's basketball or
Speaker 1: theater or badminton or Greek classics or cliff jumping or
Speaker 1: video gaming or line dancing or wine making. Whenever a
Speaker 1: task is roughly aligned with our larger goals, our brain.
Speaker 2: Circuitry comes to reflect that.
Speaker 1: Now, with how brains rewire based on what's relevant, I
Speaker 1: realized really interesting analogy some years ago. Governments do the
Speaker 1: same thing. They continually self design based on what's happening
Speaker 1: in the nation. So just look at what happened. In
Speaker 1: response to the attacks of September eleventh, two thousand and one,
Speaker 1: the United States government altered its structure. It established the
Speaker 1: Department of Homeland Security, which absorbed and restructured twenty two
Speaker 1: existing agencies, And the same thing happened with the simmering
Speaker 1: Cold War. This initiated a large shift in nineteen forty seven,
Speaker 1: which spawned the Central Intelligence Agency, and in a thousand
Speaker 1: small ways, a government subtly mirrors the current aims of
Speaker 1: a nation and the events of its outside world. So
Speaker 1: you have budgets swelling and shrinking to echo priorities when
Speaker 1: external threats loom. The military pocketbook expands when peacetime follows.
Speaker 1: Social initiatives gain. Just like brains, nations respond to changing
Speaker 1: situations by shifting their resources and redrawing their organizational charts
Speaker 1: to meet the challenges that they face. So how does
Speaker 1: the brain know when something important has happened and that
Speaker 1: it should change its wire accordingly. Well, one strategy is
Speaker 1: to turn on plasticity when events in the world are correlated.
Speaker 1: So the idea here is to just encode only those
Speaker 1: things that co occur, Like you see a cow and
Speaker 1: you hear a move, and in this way related events
Speaker 1: become bound together in the brain tissue. Now, you generally
Speaker 1: don't want to implement these changes too quickly, because sometimes
Speaker 1: there are associations that are spurious.
Speaker 2: You might see a cow.
Speaker 1: But you hear the bark of an unrelated dog, and
Speaker 1: you wouldn't want your brain to permanently store every accidental cooccurrence.
Speaker 2: So the brain solution is to change slowly, just a
Speaker 2: little at a time.
Speaker 1: And in that way it comes to encode only those
Speaker 1: things that commonly coincide real matches distinguish themselves from noise
Speaker 1: by occurring together over and over and over. But despite
Speaker 1: the wisdom of slow and steady change extracting averages like this,
Speaker 1: that's not the whole story. Because just think about one
Speaker 1: trial learning in which you, let's say, touch a hot
Speaker 1: stove and you learn not to do that again. So
Speaker 1: you've got emergency mechanisms that exist to make sure that
Speaker 1: life threatening or limb threatening events are permanently retained. The
Speaker 1: story of one trial learning goes deeper than that. Think
Speaker 1: about when you were young and your aunt taught you
Speaker 1: a new word. She says, this is called a pomegranate. Now,
Speaker 1: you didn't need to learn that in an emergency situation,
Speaker 1: and you didn't need your aunt to say this association
Speaker 1: one hundred times. She calmly told you once, and you
Speaker 1: got it in one trial. Why It's because it was
Speaker 1: salient to you. You loved your aunt, and you derived
Speaker 1: social benefit from knowing a new word and being able
Speaker 1: to ask for the delicious fruit. This is one trial
Speaker 1: learning not because of threat, but instead because of relevance.
Speaker 2: Inside the brain.
Speaker 1: This relevance is expressed through these widely reaching systems that
Speaker 1: release chemicals called neuromodulators. By releasing these with high specificity,
Speaker 1: these chemicals allow changes to occur only at specific places
Speaker 1: and times instead of all over at every moment. An
Speaker 1: especially important chemical messenger here is called acetylcholine.
Speaker 2: Neurons that release the.
Speaker 1: Seedlcholine are driven by both reward and punishment, and they're
Speaker 1: active whenever you're learning a new task and need to
Speaker 1: make changes, but they're not active once the task is
Speaker 1: well established.
Speaker 2: So here's what you need to know.
Speaker 1: The presence of acetylcholine at a particular brain area tells
Speaker 1: it to change, It doesn't tell it how to change.
Speaker 1: In other words, when the neurons that spit out acetal
Speaker 1: coline are active, they simply increase plasticity in the target areas.
Speaker 1: When they are not active, there's little or no plasticity.
Speaker 1: So here's an example. Imagine I play for you a
Speaker 1: particular note on the piano, say D flat. The note
Speaker 1: triggers activity in your auditory cortex, but it doesn't change
Speaker 1: anything about how much territory is devoted to D flat.
Speaker 2: Why not?
Speaker 1: It's because the note doesn't mean anything in particular to you. Now,
Speaker 1: let's say every time I play the note, I give
Speaker 1: you a warm chocolate chip cookie. Now the note accrues
Speaker 1: a meaning, and the brain territory devoted to D flat expands.
Speaker 1: Your brain assigns more real estate to that frequency because
Speaker 1: the presence of reward suggests it's important. Now, let's say
Speaker 1: I don't have any cookies available, so instead of handing
Speaker 1: you the treat, I play the D flat. At the
Speaker 1: same moment that I stimulate neurons in your head that
Speaker 1: release a setal colin. The cortical representation for that tone expands,
Speaker 1: just like it did with the cookies. Your brain allocates
Speaker 1: more terrain to that frequency because the presence of the
Speaker 1: acetyl coline indicates that it must be important. So a
Speaker 1: setyl colin broadcasts widely throughout the brain, and as a result,
Speaker 1: it can trigger changes with whatever kind of relevant stimulus,
Speaker 1: whether that's a musical note or a texture or something verbal.
Speaker 1: It's a universal mechanism for saying this is important. Get
Speaker 1: better at detecting this. It marks relevance by increasing territory,
Speaker 1: and changes in neural territory map on to your performance.
Speaker 1: So as an example of that, imagine that you have
Speaker 1: to learn how to play some crazy new musical instrument.
Speaker 1: So a couple of weeks of practice improves your speed
Speaker 1: and your skill, and you have a correspondingly large increase
Speaker 1: in the brain areas that are involved. But if you
Speaker 1: are a seedyl colin release is blocked with a drug,
Speaker 1: those brain areas don't grow and your skill never improves.
Speaker 1: So the basis of the behavioral improvement is not simply
Speaker 1: the repeated performance of the task. It requires these neuromodulatory
Speaker 1: systems to encode relevance. Without the acetyl coline, the ten
Speaker 1: thousand hours is wasted time. So with the hypothetical Fred Williams,
Speaker 1: who hates tennis, why didn't his brain change even after
Speaker 1: the same number of hours of practice as his sisters.
Speaker 1: It's because these neuromodulatory systems were not engaged in his
Speaker 1: head as he drilled backhands over and over. He's like
Speaker 1: you practicing the instrument with no acetal colin.
Speaker 2: As a quick side note, these acetal.
Speaker 1: Colin neurons reach out widely across the brain. So when
Speaker 1: these start chattering away, why doesn't that turn on plasticity
Speaker 1: everywhere they reach, causing widespread neural changes. The answer is
Speaker 1: that acetyl coline's release and its effects are modulated.
Speaker 2: By other neural modulators.
Speaker 1: So while acetal colon turns on plasticity, other neurotransmitters like
Speaker 1: dopamine are involved in the direction of change, encoding whether
Speaker 1: something was punishing or rewarding. Researchers all over the planet
Speaker 1: are still working to decipher this very complex choreography of
Speaker 1: the neurotransmitter systems. But what we know is that collectively,
Speaker 1: these chemical messengers allow reconfiguration in some areas while keeping
Speaker 1: the rest locked down.
Speaker 2: So let's go back to the London taxi drivers.
Speaker 1: They're famous for having to memorize the entire map of
Speaker 1: the streets of London, and they train for months and
Speaker 1: months on this task, and I mentioned before there are
Speaker 1: physical changes in the structure of their brain as a result.
Speaker 1: These cavies are able to pull off this staggering feet
Speaker 1: because the map is relevant to them. This is their
Speaker 1: desired employment, which is going to pay for their home mortgage,
Speaker 1: or their child's tuition, or their upcoming marriage. But interestingly,
Speaker 1: since the study of the cabbys was first published in
Speaker 1: the year two thousand, the need for this kind of
Speaker 1: memorization has essentially gone away. Now it's just as easy
Speaker 1: to have Google memorize all the streets of London, and
Speaker 1: more generally, all the streets interlacing the planet. So the
Speaker 1: kind of brain changes that we saw at the turn
Speaker 1: of the century, we probably.
Speaker 2: Won't be seeing in them anymore.
Speaker 1: What's interesting is that AI algorithms don't care about relevance.
Speaker 1: They memorize whatever we ask them to, which is a
Speaker 1: super useful feature of AI, but it's also the reason
Speaker 1: that AI is not exactly human like, because AI just
Speaker 1: doesn't care which problems are interesting or germane. It just
Speaker 1: memorizes whatever we feed it, So whether that's distinguishing a
Speaker 1: horse from a zebra in a billion photographs or tracking
Speaker 1: flight data from every airport on the planet, it has
Speaker 1: no sense of importance except in a statistical sense. Contemporary
Speaker 1: AI could never by itself decide that it finds irresistible
Speaker 1: a particular sculpture by Michaelangelo, or that it hates the
Speaker 1: taste of bitter tea, or that it's aroused by signals
Speaker 1: of fertility. AI can dispatch ten thousand hours of intense
Speaker 1: practice in ten thousand nanoseconds, but it doesn't favor any
Speaker 1: zeros and ones over others. As a result, AI can
Speaker 1: accomplish super impressive feats, but not yet the feat of
Speaker 1: being anything like a human who cares about some things
Speaker 1: more than others. Now, how does the modifiability of the
Speaker 1: brain and its relationship to relevance bear on the way
Speaker 1: that we teach our young The traditional classroom consists of
Speaker 1: a teacher that's droning on, possibly reading from bulleted slides.
Speaker 1: This is totally suboptimal for brain changes because the students
Speaker 1: aren't engaged, and without engagement there's little or no plasticity.
Speaker 1: The information doesn't stick. Now, we are not the first
Speaker 1: generation to make this observation. The ancient Greeks had noted this.
Speaker 1: They didn't have the tools of modern neuroscience, but they
Speaker 1: had a sharp eye, and they defined seven different levels
Speaker 1: of learning, and the highest level where the best learning occurs,
Speaker 1: is achieved when a student is invested and curious and interested.
Speaker 1: Through a modern lens, we would say that a particular
Speaker 1: formula of neurotransmitters is required for neural changes to take place,
Speaker 1: and that formula correlates with investment and curiosity and interest
Speaker 1: this trick of inspiring curiosity. This is woven into several
Speaker 1: traditional forms of learning. So, for example, Jewish religious scholars
Speaker 1: will study the Talmud by sitting in pairs and posing
Speaker 1: interesting questions to each other, like why does the author
Speaker 1: use this particular word instead of a different word? Or
Speaker 1: why do these two authorities differ in their account? Everything
Speaker 1: gets cast as a question, which forces their learning partner
Speaker 1: to engage instead of memorize. And although this is an
Speaker 1: ancient study structure, I recently stumbled on a website that
Speaker 1: poses talmudic questions about microbial biology. Questions like, given that
Speaker 1: spores are so effective in ensuring survival of bacteria, why
Speaker 1: don't all species make them? Or do we know for
Speaker 1: sure that there are only three domains of life bacteria,
Speaker 1: Archaea and Eucaria, Or how come peptides made enzematically don't
Speaker 1: seem to get strung together to make a respectably sized protein.
Speaker 2: This site has hundreds.
Speaker 1: Of questions like this, which coaxes an active engagement in
Speaker 1: its readers instead of simply telling them answers and more generally,
Speaker 1: this is why joining a study group always helps. It
Speaker 1: doesn't matter if you're studying calculus or history or whatever.
Speaker 1: A study group activates the brain's social mechanisms to motivate engagement.
Speaker 2: Now.
Speaker 1: I saw a wonderful interview in the nineteen eighties where
Speaker 1: the author Isaac Asimov gave an interview with the television
Speaker 1: journalist Bill Moyers, and Asimov saw the limits of the
Speaker 1: traditional education system with really clear eyes. And here's what
Speaker 1: he said. He said, quote, today, what people call learning
Speaker 1: is forced on you. Everyone is forced to learn the
Speaker 1: same thing on the same day, at the same speed
Speaker 1: in class. But everyone is different. For some, class goes
Speaker 1: to fast, for some, it goes too slow, for some
Speaker 1: in the wrong direction. Asimov had a vision for individualized education,
Speaker 1: although he couldn't see the details. He was squinting into
Speaker 1: the future, and he anticipated the Internet. He said, quote,
Speaker 1: give everyone a chance to follow up their own bent
Speaker 1: from the start, to find out about whatever they're interested
Speaker 1: in by looking it up in their own homes, at
Speaker 1: their own speed, in their own time, and everyone will
Speaker 1: enjoy learning.
Speaker 2: End quote.
Speaker 1: It's through this lens of triggering interest that a lot
Speaker 1: of philanthropists like Bill and Melinda Gates are aiming to
Speaker 1: build adaptive learning. The idea is you leverage software that
Speaker 1: quickly determines the state of knowledge of each student, and
Speaker 1: then instructs each student on exactly what he or she
Speaker 1: needs to know next. It's like having a one to
Speaker 1: one student teacher ratio. This approach keeps each student the
Speaker 1: right pace, meeting him where he is right now, with
Speaker 1: the material that will captivate and This past May, Saul
Speaker 1: Kahn gave a great talk at TED where he talked
Speaker 1: about using AI to personalize learning. With AI, the students
Speaker 1: can learn at their own pace and in their own way,
Speaker 1: and he's increasingly making con Academy as a way to
Speaker 1: show how AI can create totally personalized learning experiences based
Speaker 1: on that student's individual strengths and weaknesses, like asm Off
Speaker 1: and Gates and con and many others. I am a
Speaker 1: cyber optimist on the topic of education. I always find
Speaker 1: myself on Wikipedia, where I'm just following my interest. I
Speaker 1: click on one link and I'm reading, and then I think, WHOA,
Speaker 1: what's that? And I follow that link and after about
Speaker 1: twelve links, I'm down some mole hole and I think, Wow,
Speaker 1: how did I get from that topic over here? I
Speaker 1: think that drilling down through these blind mole holes of
Speaker 1: wikiped without any pre specified plan may turn out to
Speaker 1: be a near optimal way to learn and more generally,
Speaker 1: what the Internet allows is for students and all of
Speaker 1: us to answer questions as soon.
Speaker 2: As they pop into our heads.
Speaker 1: We get the answer in the context of our curiosity.
Speaker 1: And this is the powerful difference between the way that
Speaker 1: many of us grew up with just in case information,
Speaker 1: like just in case you need to know it the
Speaker 1: Battle of Hastings occurred in ten sixty six, and what's
Speaker 1: happening now, which is just in time information, which is
Speaker 1: getting the information the moment that you seek the answer.
Speaker 1: Generally speaking, it's only in the latter case, when you're
Speaker 1: doing just in time information that you find the right
Speaker 1: brew of neuromodulators present.
Speaker 2: The Chinese have.
Speaker 1: An expression an hour with a wise person is worth
Speaker 1: more than one thousand busos, and this insight is the
Speaker 1: ancient equivalent of what the Internet offers.
Speaker 2: When the learner can actively direct her.
Speaker 1: Own learning by asking the wise person precisely the question
Speaker 1: that she wants to answer, the molecules of relevance and
Speaker 1: reward are present.
Speaker 2: They allow the brain to reconfigure.
Speaker 1: When you toss facts and an unengaged student, it's like
Speaker 1: throwing pebbles to dent a stone wall. It's like trying
Speaker 1: to get Fred Williams to absorb tennis. So in this
Speaker 1: light we have great opportunities because of the gamification of education.
Speaker 1: You have this adaptive software which keeps students working at
Speaker 1: their point of struggle, where finding the right answer is
Speaker 1: frustrating but achievable. If the student can't get the answer,
Speaker 1: the questions stay at the same level. When he gets
Speaker 1: the right answer, the questions get harder. So there's still
Speaker 1: a role for the teacher here to teach foundational concepts
Speaker 1: and to guide the path of learning. But fundamentally, given
Speaker 1: how brains adapt and rewrite their wiring, a neuroscience compatible
Speaker 1: classroom is one in which the students drill into the
Speaker 1: vast sphere of human knowledge by following the paths of
Speaker 1: their individual passions. So the future of education looks very favorable.
Speaker 1: But one question remains, and I just want to address
Speaker 1: this here because I get asked this so often. Given
Speaker 1: that the brain becomes wired from experience, what are the
Speaker 1: neural consequences of growing up on screens? Are the brains
Speaker 1: of digital natives different from the brains of the generations
Speaker 1: before them. Now, it comes as a surprise to many
Speaker 1: people that there aren't more studies on this than neuroscience.
Speaker 1: Wouldn't our society want to understand the differences between the
Speaker 1: digital and analog raised brain.
Speaker 2: Yes, we would. But the reason there are no.
Speaker 1: Good studies on this is because it's inordinately difficult to
Speaker 1: perform meaningful science on this. Why because there's no good
Speaker 1: control group against which to compare a digital native's brain.
Speaker 1: You can't easily find another group of eighteen year olds
Speaker 1: who haven't grown up with the Internet. You might find
Speaker 1: some Amish teenagers in Pennsylvania, but there are dozens of
Speaker 1: other differences with that group, such as religious and cultural
Speaker 1: and educational beliefs. Where else could you find young people
Speaker 1: of the same age who grew up without access to
Speaker 1: the Internet. You might be able to turn up some
Speaker 1: impoverished children in rural China, or in a village in
Speaker 1: Central America or in the Kalahari Desert, but there are
Speaker 1: going to be other major differences with those children and
Speaker 1: the digital natives whom you intended to understand, including wealth
Speaker 1: and education and diet, So it's not a useful control group. Okay,
Speaker 1: So maybe you could compare millennials against the generation that
Speaker 1: came before them, like their parents, who didn't grow up online,
Speaker 1: but who instead played street stickball and stuffed twinkies in
Speaker 1: their mouths as they watched The Brady Bunch. But this
Speaker 1: is also problematic because between two generations there are innumerable
Speaker 1: differences of politics and nutrition and pollution and cultural innovation,
Speaker 1: such that if you find differences in the brain, you
Speaker 1: have no idea what to.
Speaker 2: Attribute it to.
Speaker 1: So this is an intractable problem to pull off a
Speaker 1: well controlled experiment about the effect of growing up with
Speaker 1: the Internet. Nonetheless, I can tell you the root of
Speaker 1: my optimism about this. Never before have we had the
Speaker 1: entirety of humankind's knowledge in a rectangle in our pockets,
Speaker 1: with constant and immediate access. Some of you will remember
Speaker 1: taking trips down to the library and you look around
Speaker 1: for the Encyclopedia Britannica, and you find the letter and
Speaker 1: you hope there's an article there about what you're looking for,
Speaker 1: and if it's there, you hope that it's not too
Speaker 1: many decades old and that the information is still relevant.
Speaker 1: And if you can find an article there, then you
Speaker 1: have to go to the card catalog and you flip
Speaker 1: through it and hope that there's a book somewhere in
Speaker 1: the library that addresses what you want to know in
Speaker 1: a surprisingly brief period. This is all changed, and as
Speaker 1: a result, we've all seen the transition of dinner time debates,
Speaker 1: where the winner has transitioned from being the loudest or
Speaker 1: most pervasive to the person who can whip out the
Speaker 1: phone the fastest and google the fact in question. Discussions
Speaker 1: move really rapidly now, they leap from one solved question
Speaker 1: to the next, and even when we're by ourselves, there's
Speaker 1: just no.
Speaker 2: End to the learning that goes on. When we look up.
Speaker 1: The Wikipedia page, which cascades is down the next link
Speaker 1: in the next such that six jumps later, we're learning
Speaker 1: facts that we didn't even know we didn't know.
Speaker 2: And the great advantage of this comes from a simple fact.
Speaker 1: All new ideas in your brain come from a mashup
Speaker 1: of previously learned inputs, and today we get more new
Speaker 1: inputs than ever before. And so our children are living
Speaker 1: in a time unparalleled in richness. Our knowledge sphere has
Speaker 1: exploded in diameter, and as it grows, it offers more
Speaker 1: doors for entry. So young minds have the opportunity to
Speaker 1: cross link facts from completely different domains to generate ideas
Speaker 1: that previous eras couldn't even have imagined, and this partially
Speaker 1: explains the exponential increase in human scholarship. We have faster
Speaker 1: communication and more mashups than ever before. So it's not
Speaker 1: clear what all the social and political consequences of the
Speaker 1: Internet will be, but from a neuroscience perspective, it unlocks
Speaker 1: a much richer level of education. So in earlier podcasts
Speaker 1: we looked at brain changes resulting from changes to the
Speaker 1: body plan in terms of either new sensors or new limbs,
Speaker 1: and in this episode we turn to changes that result
Speaker 1: from practiced motor acts or rewarding sensory inputs. But the
Speaker 1: larger principle that ties all these scenarios together is relevance.
Speaker 1: Your brain adjusts itself according to what you spend your
Speaker 1: time on as long as those tasks have alignment with
Speaker 1: rewards or your goals. For a person who goes blind,
Speaker 1: expanding the other senses takes on a heightened relevance, and
Speaker 1: this is the deeper origin behind the changes that allow
Speaker 1: her visual cortex to get taken over. If a person
Speaker 1: passes her fingers repeatedly over the bumps of braille but
Speaker 1: has no motivation to learn it then no rewiring takes
Speaker 1: place because the right.
Speaker 2: Neuromodulators just aren't present.
Speaker 1: And in the same way, if you add a new
Speaker 1: telelimb to your body and it has relevance to you,
Speaker 1: your body will learn how to use that, just like
Speaker 1: Faith the dog mastered a unique body plan and learned
Speaker 1: how to walk on her back legs because it mattered
Speaker 1: to her. So the lesson I want to leave you
Speaker 1: today with is when you need to learn something, find
Speaker 1: some aspect of that that matters to you. My students
Speaker 1: ask me this all the time about advice on getting
Speaker 1: through their final exams, and I tell them it's all
Speaker 1: about relevance. Figure out what is the aspect that matters
Speaker 1: to you. You're facing this dumb exam that you might
Speaker 1: not care about, but you do care about getting into
Speaker 1: graduate school and this is one important wrong on the
Speaker 1: ladder to get there. Or you want to impress that
Speaker 1: girl or boy over there, and so you need to
Speaker 1: study so you can have this stuff on the tip
Speaker 1: of your tongue. Or you appreciate the sacrifice that your
Speaker 1: parents made in getting you here and you want to
Speaker 1: make them proud and that would be meaningful to you,
Speaker 1: or whatever the personal details don't matter, but the key
Speaker 1: is to remind yourself of the relevance so you can
Speaker 1: plug into that, so you can get the right neurotransmitters present,
Speaker 1: so they can make the impression, so that they can
Speaker 1: make the information stick, so that you're not like Fred
Speaker 1: Williams who swings at the tennis ball but whose brain
Speaker 1: doesn't change, but instead you're taking in the information and
Speaker 1: you're making these changes in your forests of neurons so
Speaker 1: that you can recall it later.
Speaker 2: That's what brain plasticity is all about.
Speaker 1: Go to Eagleman dot com slash podcast for more information
Speaker 1: and to find further reading on all of this. Send
Speaker 1: me an email at podcast at eagleman dot com with
Speaker 1: questions or discussion, and I'm making sporadic episodes in which
Speaker 1: I address those until next time. I'm David Eagleman, and
Speaker 1: this is Inner Cosmos.