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Dr. Eagleman on Huberman Lab: Why cortex repurposes itself

Cortex rewires based on what feeds into it, Eagleman maintains; challenge fuels plasticity and novelty sustains it, even rerouting auditory cortex for vision.

Dr. David EaglemanguestAndrew Hubermanhost
Jan 26, 20262h 24mWatch on YouTube ↗

EVERY SPOKEN WORD

  1. 0:00 – 2:35

    David Eagleman

    1. DE

      oftentimes people will ask me, uh, like an older person will say, "Hey, I do crossword puzzles. Is that good?" Y- yeah, it's good until you get good at it, and then stop and do something that you're not good at.

    2. AH

      Yeah.

    3. DE

      And constantly find the next thing that's a real challenge for you. That's the key thing about plasticity. Your brain is locked in silence and darkness. It's trying to make a model of the outside world, and if you're constantly pushing and challenging it with things it doesn't understand, then it'll keep changing. [upbeat music]

    4. AH

      Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. My guest today is Dr. David Eagleman. Dr. David Eagleman is a neuroscientist, a bestselling author, and a longtime science public educator. Today, we discuss several different features of brain science that impact your everyday life, and once you understand the mechanisms behind these features, it will position you to make better decisions, and if you choose, to rewire your brain to be a more effective learner. We start by discussing neuroplasticity, which is your brain's ability to change in response to experience or any form of deliberate learning that you are trying to impose on yourself. We talk about the mechanisms for it and how you can get better at learning and unlearning in the context of skills and information. We also discuss memory formation and the relationship between stress and time perception, and why it is that people experience things in slow motion if those things are very stressful or traumatic, and how that can be useful for undoing traumatic memories. David also takes us through the neuroscience of cultural and political polarization, something that's very timely right now, false memories, deja vu, dreams, and the meaning of dreams, and a lot more. David is an absolutely legendary science communicator. I say this as a fellow neuroscientist. He is able to embed factual information about the brain into real-life stories, and in doing so, he's able to shed light on how we work as humans and how we can all improve our life experience. He's a true virtuoso of neuroscience and science education more generally. What David shares with us today will change the way that you think about thinking and your own mind, and no doubt will also change the way that you view the world. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science-related tools to the general public. In keeping with that theme, today's episode does include sponsors. And now for my discussion with Dr. David Eagleman.

  2. 2:35 – 11:07

    Neuroplasticity & Learning; Cortex, Flexibility & Repurposing, Savantism

    1. AH

      Dr. David Eagleman, welcome.

    2. DE

      Thanks! Great to see you, Andrew.

    3. AH

      Man, I feel like the kid that was a freshman when you were a senior-

    4. DE

      [laughing]

    5. AH

      ... because you got into this public-facing science education long before I did, and you've had a, an am- amazing career, also in your laboratory work. And today, I wanna talk about all of it-

    6. DE

      Great

    7. AH

      ... um, by mostly listening and you doing the talking. And there are so many topics in neuroscience that are fascinating, as you know, but I think perhaps the most fascinating thing about the human brain is its ability to change itself.

    8. DE

      Yeah.

    9. AH

      Plasticity. So I know how I think about neuroplasticity. I wanna know how you think about neuroplasticity, what it is, and how we should think about it, and what we could possibly do with that information.

    10. DE

      Okay, great. I mean, this was Mother Nature's big trick with humans, was figuring out how to drop a creature into the world with a half-baked brain and then let the world wire up the rest of it. And so, you know, 1953, Crick and Watson, I worked with Crick at the Salk, they burst into the Eagle and Child Pub and said, "We've discovered the secret to life," 'cause they figured out the structure of DNA. But that was really half the secret of life, because the other half is all around us. It's every bit of experience that you have. It's your culture, it's your language, it's your neighborhood. All of that stuff gets absorbed by the brain and wires us up. And I often think about this issue of, what if you were born 30,000 years ago, exactly your DNA, you pop out and you look around, and the question is, would you be you? The answer is, y- you wouldn't be. You'd look maybe similar, 'cause of the same genetic blueprint, but you would have a different culture and a different language and different stories and all that stuff. You'd be a very different kind of person. So brain plasticity, for anyone who doesn't know, it's, it's that the brain is constantly reconfiguring itself every second of your life. You got 86 billion neurons, and really, the way to think about it is, these are like little creatures that are all crawling around and moving around. Each one is, you know, on average, contacting 10,000 of its neighbors, but it's not like a fixed thing like you might see in a textbook. Instead, they're, you know, plugging and unplugging and searching around and finding new places to plug in, and of course, changing the strength of those connections. And I actually always find this weird. It's like having all these little creatures in your head that are slithering around, but that's what makes us absorb every single thing in our worlds. And this is what, uh, you know, humans have that other creatures have less of, and that's why we've taken over every corner of the Earth. That's why we have 60... We've gotten off the planet. We build skyscrapers and compose symphonies and so on because each generation, we land, and we get to spend our first few years absorbing everything that's been discovered before us, and then we springboard off of that and do something new. Because we are able to figure out all the discoveries that have come before us because of this ability to reconfigure our own circuitry.

    11. AH

      Yeah.

    12. DE

      And, uh, you know, if you were a, an alligator born 30,000 years ago, you'd be the same alligator. [chuckles]

    13. AH

      Yeah.

    14. DE

      You know, eat, mate, swim, whatever, and you, you wouldn't be meaningfully different. But, uh, but humans, because of our flexibility, we are the, the dominant species.

    15. AH

      Such an interesting take on-... time in human evolution that, uh, and I completely agree with you, I just had never thought of it, about it this way before, that we land, uh, when we're born, and we're absorbing the, um, [lips smack] the outcroppings of all the neuroplasticity that came before us. We often hear that, you know, the, the human brain is, is kinda like a macaque monkey brain with a supercomputer added on top of it, mostly the prefrontal cortex. A bit more prefrontal cortex, prefrontal cortex, prefrontal cortex, prefr- [chuckles] it's actually-

    16. DE

      We hear cortex in general.

    17. AH

      Okay, interesting, so-

    18. DE

      Well, 'cause we, we have four times as much cortex as our nearest neighbors in the animal kingdom, and that seems to be the magical stuff, so-

    19. AH

      Not just prefrontal cortex.

    20. DE

      Right. And for... I'm sure the listenership knows this, but, you know, uh, the cortex is just the outer three millimeters of the brain. It's that wrinkly bit, and that's the magic stuff because it turns out cortex is a one-trick pony. The, the reason the cortex looks the same everywhere is because it is the same. It's got the same circuitry, it's got six little layers, it's doing the same algorithms, and it gets defined by what you plug into it. So if you plug in a cable that's carrying visual information, then it becomes visual cortex, and we look at it, and we say, "Oh, look, it detects the orientation of lines, and it detects motion," things like that. If you plug auditory information into it, it becomes auditory cortex, and so on. And it turns out, you know, the way we do this in textbooks is we make a picture, and we say, "Look, that's visual cortex, that's auditory, that's somatosensory." But all this stuff is really flexible. It's, it's so much more interesting than the textbook model because you can take the fibers and plug 'em in somewhere else. So you may know this study in 2000 by Mriganka Sur at MIT-

    21. AH

      Mm-hmm

    22. DE

      ... where he, in a ferret, took, uh, the visual information, visual, uh, the optic nerve, and he plugged it into the visual- uh, sorry, into the auditory cortex. And then the, what would have been the auditory cortex became visually responsive, and it started caring about vision. So what does that mean? It means the cortex is a one-trick pony, and we got so much more of it, including the prefrontal cortex. So that has two major effects. One is that there's a lot more room with our species in between input and output. [lips smack] So with a, a, a squirrel or a cat or even a macaque monkey, you know, you throw some food in front of it, it- that, that sensory cortex is right next to the motor cortex. It's gonna eat the thing, but we've got all this computational real estate in between in and out. So we can say, "Well, I'm on a diet. I'm try-," whatever. "You- I'll eat it later." We've got all these other options that we can take. That's one thing, and then the other thing is exactly what you pointed to, which is the prefrontal cortex, which allows us to simulate what-ifs.

    23. AH

      Mm-hmm.

    24. DE

      Allows us to think about possible futures, simulate things in a way that we don't have to risk our lives doing it. We can simulate it and say, "Oh, that would be a bad idea. Oh, that'd be a pretty good idea," and then we can take the action.

    25. AH

      Couple different questions. Um, I'm a big fan of Mriganka's work, and I'm so glad you mentioned that work. It, it really points to the fact that while there are cortical areas that are, uh, genetically devoted by virtue of wiring when we arrive in the world to auditory or visual, that there's a lot of crossover, especially in the extreme cases. So my understanding, correct me if I'm wrong, is that, um, if somebody is blind from birth, the real estate that would be allocated to vision becomes allocated to tactile sensation, especially if they learn how to Braille read, um, maybe auditory processing, and because they rely on it more. So there's really no blank real estate in the cortex. It's all used.

    26. DE

      That is exactly right.

    27. AH

      Mm-hmm.

    28. DE

      So it turns out, um, you know, right, people who are born blind, what we call the visual cortex in the back of the, back of the head here, that gets taken over. It's no longer visual. It becomes devoted to hearing, to touch, to memory, things like this, and you can demonstrate that people who are born blind are better at hearing and, and at touch, and so on. They can discriminate things much more finely. Um, same with people who go deaf, that the auditory cortex, all that real estate, nothing lies fallow in the brain. All that gets taken over for different tasks, and they can do things like see your accent. You know, just by lip-reading, they can tell where in the country you're from, and so on. Um, uh, all of this demonstrates that, first of all, the more real estate you have, the better. We are, in a sense, if you've got all your senses, you, uh, you have to share everything, and so we're pretty good at vision, and, uh-

    29. AH

      Mm-hmm

    30. DE

      ... hearing and touch, and so on, but everything has to get shared. But there are pretty extraordinary things that happen when people devote more real estate towards one task. And by the way, just as a side note, this is one hypothesis about what goes on with savantism in, in autism, is that somebody, for whatever genetic set of reasons, ends up devoting a ton of real estate to, let's say, the Rubik's Cube or the piano or memorizing visual scenes or something, and then they are absolutely superhuman at it. That comes at the cost of other things, let's say social skills that might be needed, um, but the general story is, if you devote a lot of real estate towards something, you're gonna get really good at it.

  3. 11:07 – 13:27

    Sponsors: Mateina & Rorra

    1. AH

      I'm excited to share with you that Mateina, the yerba mate drink that I helped create, is now available at Sprouts market nationwide. Longtime listeners of the Huberman Lab podcast know that yerba mate is my preferred caffeine source. It provides a smooth energy lift without giving you the jitters, and it has many other benefits, such as helping regulate blood sugar, improving digestion, mild appetite suppression, and more. Mateina is my absolute favorite of all the yerba mate brands out there, and believe me, I've tried them all. The flavors are fantastic. I drink at least three cans of Mateina every single day. You'll often see them on the table during our podcast recordings. I absolutely love the product, and I'm proud to now have it sold at Sprouts market. Also, there's a great new offer. They are giving away a free can of Mateina to anyone who buys it at Sprouts and sends in a photo of their receipt. To learn more about how you can get a free can of Mateina, go to drinkmateina.com/offer. Again, that's drinkmateina.com/offer to get a can of Mateina for free at your local Sprouts market. Today's episode is also brought to us by Rorra. Rorra makes what I believe are the best water filters on the market. It's an unfortunate reality, but tap water often contains contaminants that negatively impact our health. In fact, a 2020 study by the Environmental Working Group estimated that more than two hundred million Americans are exposed to PFAS chemicals, also known as "forever chemicals," through drinking of tap water. These forever chemicals are linked to serious health issues, such as hormone disruption, gut microbiome disruption, fertility issues, and many other health problems. The Environmental Working Group has also shown that over one hundred and twenty-two million Americans drink tap water with high levels of chemicals known to cause cancer.... It's for all these reasons that I'm thrilled to have Rorra as a sponsor of this podcast. I've been using the Rorra countertop system for almost a year now. Rorra's filtration technology removes harmful substances, including endocrine disruptors and disinfection byproducts, while preserving beneficial minerals like magnesium and calcium. It requires no installation or plumbing, it's built from medical-grade stainless steel, and its sleek design fits beautifully on your countertop. In fact, I consider it a welcome addition to my kitchen. It looks great, and the water is delicious. If you'd like to try Rorra, you can go to rorra.com/huberman and get an exclusive discount. Again, that's Rorra, R-O-R-R-A, .com/huberman.

  4. 13:27 – 22:05

    Specialization vs Diversification, Practice; Internet & Curiosity

    1. AH

      I don't know if you saw this study, uh, that was published in Science recently ab- that explored, um, early specialization in sport or creative endeavor-

    2. DE

      Mm

    3. AH

      ... versus kids that played a bunch of different sports or involved in a bunch-

    4. DE

      Wow

    5. AH

      ... of different creative endeavors, and it turns out that, um, specializing too early, on average, doesn't play out so well in terms of, um, kind of, uh, peak of success later.

    6. DE

      Yeah.

    7. AH

      Now, there are exceptions, right? But, um, turns out that being, uh, a bit more diversified in, in your, uh, physical activities and cognitive activities as a, as a young person, um, into the early teens even, um, and beyond, uh, is more beneficial. And this, this to me kind of runs counter to my images of, like, um, Tiger Woods, uh-

    8. DE

      Yeah

    9. AH

      ... putting, uh, golf balls with his, uh, dad when he was, you know, kind of still waddling, he was so little, right?

    10. DE

      Right.

    11. AH

      And then he becomes Tiger Woods. Or, um, or the Williams sisters, who were, you know, playing tennis early on. I think that especially in the United States, we have this notion that early specialization is really what sets you up-

    12. DE

      Mm

    13. AH

      ... to be spectacularly good later. So I'm curious what your general thoughts are for the, the every person. I mean, you have kids, um, and some of us still are kids who are listening [chuckles] -

    14. DE

      [chuckles]

    15. AH

      ... and, and we all have plasticity-

    16. DE

      Yeah

    17. AH

      ... into adulthood. You know, it's a- do you think that we come into the world with some genetic leanings toward particular activities being right for us or more right for us? And how do you think about it in terms of how many difficult, hard-to-access things we do just so that we're sure that we have a full experience of life? Because what I hear you saying, and I-

    18. DE

      Mm

    19. AH

      ... totally subscribe to, is that our early experience becomes the funnel through which we have more or less opportunity later. Like, the kind of width of the fu-

    20. DE

      Yeah

    21. AH

      ... of the funnel depends on how many things we did or didn't do early on.

    22. DE

      So this is really interesting because, um, first of all, take somebody like the Williams sisters. They got drilled on tennis from day one, and this stuff can be taught, and this is why they became champions. And ob- this is obvious, but this is the same way you find with chess champions and golf champions, like Woods and so on. Um, you have to really spend the time doing it. Now, uh, I find this interesting for a few reasons. One is that cognitively, you can understand how to, you know, what a forehand or a backhand s- you know, is, a hit in tennis, but to actually get good at it, you have to burn it down into the circuitry. So le- actually, let me back up for one second, which is, the reason that we have brain plasticity is because this is how a brain makes things that you do fast and efficient.

    23. AH

      Mm-hmm.

    24. DE

      So when you're doing a task a lot, like ser- you know, serving tennis or something, you're taking that from the software to the hardware of the brain. Let's say, uh, I'm an amateur tennis player, and, and there's Serena Williams, I'm playing against her. Um, it turns out, surprisingly, when we're playing, she's beating me like crazy, but my brain's the one using all the activity. I'm the one burning all the calories with my brain. Why? Because she has burned tennis into the hardware of the brain, so it's fast and efficient.

    25. AH

      Mm-hmm.

    26. DE

      I, on the other hand, am trying to simulate lots of things and figure out where I should go and all that. So the brain does this for reasons of efficiency. Obviously, the brain's main job is to save energy because we are mobile creatures who run on batteries, and so, um, this is one of the big things about, about plasticity. So people get extraordinarily good by doing things over and over. The, the, these, these three women, the Polgar sisters, who are chess champions, they're, you know, the best, uh, to my knowledge, are still the best three female chess players in the world. Their father from day one started teaching them how to do chess and so on, and they all became, uh, world champions at this. Uh, you know, the thing about whether you need to have d- diversification, that's an interesting question. I can see why it would be useful because you're learning different ways, different moves about it, in the same way that if you learn how to snowboard and ski, um, you know, you might, y- you might get better at both of them. But I, I gotta say, uh, when children grow up, let's say, trilingually, uh, or even bilingually, they, they end up having a lower vocabulary in both languages than if they grow up, uh, monolingually.

    27. AH

      Really?

    28. DE

      Yeah. It's just because of the amount of practice you get with a language.

    29. AH

      Kids, still do your, uh, second language homework. [chuckles]

    30. DE

      Yeah. [chuckles] Right.

  5. 22:05 – 28:18

    Building a Well-Rounded Brain, Tool: Critical Thinking & Creativity

    1. AH

      given what you know about plasticity and the fact that, yes, you know, we come into the world with some pre-programming of our, of our brain circuitry, but we have some control over, uh, what the inputs are, some-

    2. DE

      Mm

    3. AH

      ... depending on our circumstances.

    4. DE

      It depends what you mean by we. Uh, so as infants, of course, we have no control over that.

    5. AH

      Right.

    6. DE

      Our parents and we-

    7. AH

      As an adolescent, as a teen-

    8. DE

      Yeah, fair enough

    9. AH

      ... as a 20-year-old, assuming-

    10. DE

      Yes

    11. AH

      ... plasticity extends into adulthood, still as adults, although it's harder.

    12. DE

      Quite right.

    13. AH

      Um, some control over what one learns or does. What do you think are, um, sort of the core elements to, uh, making sure you build a healthy, well-rounded nervous system?

    14. DE

      Yeah.

    15. AH

      Nobody's really ever attempted to answer this question. You know, a howler monkey learns all the things that a howler monkey needs to do.

    16. DE

      Yeah.

    17. AH

      Um, humans, we have, as you said, the benefit of all the technology that comes from the plasticity of those that came before us, and so, you know, maybe kids don't need to learn a second language. But what, what do you think are sort of the, the essentials? I mean, obviously, learning to communicate and understand, learning to move, but do we have some sense of, of how you check off the like, the core 10 boxes of neuroplasticity to make sure that by the time-

    18. DE

      Mm

    19. AH

      ... you land in adulthood, or even if you're still an adult, that you're, you're doing the, quote-unquote, "best that you can with your brain?" This is a tough question, I realize.

    20. DE

      I mean, I would say two things. One is, um, you know, try to maximize along every axis. So try to be an athlete, try to be a scholar, try to be, uh, you know, uh, uh, somebody who's good at social life and has a lot of friends. All, all of these axes of life, it's worth spending the time doing that, and obviously, we're in an era, especially now, where there are a million ways to waste time. I sit on airplanes next to people, and they're playing Candy Crush for the whole flight, and I just feel like, "What a shame," 'cause there's so much you could be putting into your brain and making happen. You could be reading books, you could be listening to podcasts, anything like that. Okay, so there's that. But the other half that I would say is, um, a lot of w- w- what we care to be depends a lot on what's going on in the future, and I, I'm fascinated by, for children now in schools, w- what choices they should make, because who the heck knows what careers are going to exist in 20 or 30 years from now? Therefore, the main things they can concentrate on, I think, are critical thinking and creativity. Those are the main things for them to figure out how to do.

    21. AH

      What are some good ways, uh, in your opinion, to access critical thinking and creativity? I, I can imagine-

    22. DE

      So

    23. AH

      ... a number of them.

    24. DE

      Yeah. Here's something I find very optimistic about AI in the realm of education. Um-... you know, in any classroom, it's going too fast for half the kids and too slow for the other half of the kids. What we now have the opportunity for is really individualized education. One way this could be implemented is AI debate. So you take any hot button issue, abortion, gun control, whatever you want, and you debate with the AI, and you get graded based on the quality of your arguments. And then you switch sides, and you take the other side, and you argue again.

    25. AH

      Mm.

    26. DE

      This is the kind of thing you could never have enough teachers for, they would never have enough patience for. AI is terrific at this, and by the way, it's really important so that students get a 360 view of issues instead of ideological capture. So this is a terrific way to teach critical thinking-

    27. AH

      Mm

    28. DE

      ... to every student, not just the kids on the speech and debate team. Okay, creativity, that's easy. That has to do with learning the foundational stuff and then doing remixes, bending, breaking, blending, doing new versions of it, and I think schools can implement this easily and without any extra expense, which is, you have to teach the foundational stuff, but you compress that so you have one extra week at the end of each semester, and then that last week, you say, "Okay, great, take everything you've learned and now make your own thing with it, using all the elements that we've learned. Bend it, break it, blend it, and make your own version of this."

    29. AH

      Mm-hmm.

    30. DE

      That kind of exercise is-- that is creativity. That's all creativity is, is taking your storehouse of knowledge and doing remixes.

  6. 28:18 – 32:41

    Neuroplasticity & Adults, Tools: Novelty & Challenge

    1. AH

      we have a lot of friends that are neuroscientists, but I have a feeling you've thought about this more than anyone, which is, are there any things that we can do to extend the window of plasticity-

    2. DE

      Mm

    3. AH

      ... or are there activities like learning an instrument or, or some sort of game, who knows, that gives us our capacity for plasticity, uh, more height, more width? Um, as opposed to just, you know, the same principles. You need to focus on the thing, then you need to make errors, and you need to do some error correction. You get to sleep that night, you rewire, you give it trial and error. I mean, we know the, the basics now. I think most people have heard them. But what can we do to broaden our ability or heighten our ability to get c- uh, plasticity?

    4. DE

      Two words: seek novelty. That's the whole game, is you gotta continually challenge the brain, and this is something that, as we get older, is more important than ever. It's finding new things that we haven't done before. You always have to keep yourself between the levels of frustrating but achievable.

    5. AH

      Mm-hmm.

    6. DE

      And as long as you're trying new things... So yes, a new instrument is great. Uh, speaking a new language is great. Um, you know, obviously, we're in a world that's moving very fast, so just keeping up with the technology and figuring out, "Wow, there's this new o- opportunity here with this piece of software," or whatever, all that stuff is great. This is the critically important part. Um, y- you may know of these studies. There's been this, this study going on for, uh, decades now called the r- the, what is it? The Religious Orders Study, uh, up in Chicago area, where there's a whole bunch of nuns and priests that agreed to donate their brains when they passed away. And then when they donate their brains, the researchers, uh, you know, examine them, do autopsies on them. What the researchers found is that some fraction of these nuns had Alzheimer's disease, but nobody knew it when they were alive. Nobody saw any cognitive deficits. Why? It's because these, these women died in their 90s, and to the day they died, they lived in these convents, and in the convents, they had social responsibilities, they had chores, they were fighting with their sisters, they were playing games with their fellow sisters, they were singing songs. They were doing things all the time, so they kept their brain active. So even as their brain was physically degenerating with Alzheimer's disease, they were building new roadways. They were building new bridges over these areas. This is one of the big things that tells us that, uh, y- you know, contrast this with, with people who retire at 65, and they go home, and they sit on a couch and watch the television.... they don't have as good an outcome because they're not challenging their brain anymore. Um, so i- it is so important to be doing things, uh, you know, I, I once heard the expression that there's nothing as hard that the brain does than other people, and so for these, for these women living in convents, they were constantly dealing with- 'cause you never know what somebody's gonna say or how they're gonna react or what they're going to do. So this is great challenge opportunity for the brain. Anyway, the point is, we need to always find that with ourselves. Uh, oftentimes people will ask me, uh, like an older person will say, "Hey, I do crossword puzzles. Is that good?" Yeah, it's good until you get good at it, and then stop and do something that you're not good at, and constantly find the next thing that's a real challenge for you. That's the key thing about plasticity. Essentially, the backstory is this: as you well know, your brain is locked in silence and darkness. It's trying to make a model of the outside world, and its whole goal is to make a successful model, and when it succeeds at that, and says, "Oh, okay, wait, I g- I've got good predictions about what's going on," then it stops changing, and that's its goal is to stop changing. And if you're constantly pushing and challenging it with things it doesn't understand, then it'll keep changing.

    7. AH

      Amen to that. I, I've been trying to beat the drum that the agitation that one feels when trying to learn something new-

    8. DE

      Yeah

    9. AH

      ... it's actually a reflection in, in part of the catecholamines, right? Like adrenaline and norepinephrine.

    10. DE

      Yeah.

    11. AH

      The frustration and the agitation that we feel, that's the feedback signal to the brain that, "Hey, this is different than the, the stuff you know how to do."

    12. DE

      Yeah.

    13. AH

      Um, because the, the neurons are not thinking, they're firing, right? [chuckles]

    14. DE

      Right.

    15. AH

      And so, and so that neurochemical milieu associated with frustration is one of the triggers that, uh, generates plasticity, which actually, maybe you can resolve this question for me. I'm struck by the fact that there are so many studies showing that the adult brain

  7. 32:41 – 38:50

    Neuromodulators & Plasticity, Psychedelics; Directed Plasticity

    1. AH

      can change.

    2. DE

      Yes.

    3. AH

      And some of the more interesting ones, um, involve boosting the levels of some neuromodulator, dopamine or acetylcholine or norepinephrine or epinephrine, serotonin, but what's so interesting to me is that it seems like you can boost the levels of any of those and get plasticity.

    4. DE

      Mm.

    5. AH

      It's not like one neuromodulator gives you, uh, the opportunity for, for plasticity. So many of the interesting studies on psychedelics are using psychedelics that are kind of like serotonin. I mean, they act on different receptors-

    6. DE

      Yeah

    7. AH

      ... but they're very serotonergic.

    8. DE

      Yeah.

    9. AH

      I, I remind people of this because people really like to, um, beat up on SSRIs, and I agree they have their problems and side effects, but they've also helped a great number of people.

    10. DE

      Yeah.

    11. AH

      But whether it's SSRIs or it's psilocybin, they're both just tools for plasticity-

    12. DE

      Mm

    13. AH

      ... that drive serotonin, but we know you can amplify acetylcholine and get a window of plasticity. This is a speculative question, but why do you think it is that there's this sort of equipotential of neuromodulators, where boosting any one of them can open plasticity or the window-

    14. DE

      Mm

    15. AH

      ... or the opportunity for plasticity?

    16. DE

      Okay, a few things on this. As, as you well know, you know, all the neuromodulators exist in a dance with each other, and, and fundamentally, I think we're gonna come to understand this in 50 years as, you know, sort of combination locks of things. And the way we keep looking at it in science currently is, "Ah, here's acetylcholine," or, "Here's serotonin," and so on.

    17. AH

      Mm.

    18. DE

      And it's probably not the right way to look at it. It's certainly not how the neurons are looking at it. Okay, that said, acetylcholine r- really feels to me like the main one involved in plasticity. When you are a baby, you've got acetylcholine going everywhere. Whenever you're trying to figure out the world, whenever something's not matching a prediction, and you've got, uh, acetylcholine going everywhere that says, "Hey, s- I, I gotta figure out what just happened and how to link this with what I did," and so on. As you get older, it's more like, you know, a, a pointillist artist who just dabs things here or there. You get acetylcholine release very locally, in very, in, in small places, and that's where you make changes. Why? That's because as you get to be an adult, you've got a better and better model of the world, and you don't want to change everything. You just change, like, "Oh, I didn't realize there was that button on the coffee machine that did this new thing," or whatever. So you just change little bits at a time here. We're in this really interesting situation in, in the history of our species, where now we can do things like, "Hey, what if we just crank up acetylcholine?" Or, you know, obviously, we've done lots of things with, with dopamine. Um, w- we always find when we tweak these things, that it's complicated. Just as one example, you know, with Parkinson's, people get, have less dopamine, and so the medications are to crank up the dopamine. But what that led to, you may know this fascinating story, this is probably 25 years ago now, where, uh, uh, you know, observant clinicians noted that people on these Parkinson's medications were becoming hyper-compulsive gamblers. They were blowing their family's fortune on online gambling in Las Vegas and so on. And, and what they realized is when you crank up the dopamine, that changes your risk aversion, such that people are taking... So now it's a, it's a contraindication that's listed on the bottle. You know, if you notice gambling, turn down the, the, the, the amount here. So anyway, whenever we, whenever we start dialing these around, we always find things that are a little bit out of our predictive realm. Um, but, uh, the general story is that your brain's trying to put together this model of what's going on, and as it gets better and better, it's doing less and less plasticity. I do want to point out, though, that parts of the brain become less plastic and others stay plastic your whole life. As an example, your primary visual cortex at the back of the head, that locks down early. You really can't do much to change that. And, um, you know, there were studies by Logothetis' lab years ago, where they looked at changes to, let's say, the retina in an adult monkey, and they expected to see changes in the visual cortex of the monkey, and they didn't see any changes at all. And that surprised them, given all the plasticity literature. But it's because the visual cortex locks down. In contrast, these downstream areas from the visual cortex that care about things like recognizing faces or new brands of, uh, fast food restaurants or whatever it is, those stay plastic your whole life because there's constantly new data coming in on those. So the general story is, the primary areas are like the... I think about it like the-... the software kernels where, you know, if you're at Microsoft, for example, there's parts of the code that no one ever touches, 'cause that's like how to add two numbers and multiply or whatever. That's the kernel of the code. You never touch that. But you get these higher and higher application layers on top of that, and that's essentially how to think about primary sensory cortices and then all the stuff downstream from there.

    19. AH

      Mm-hmm. Perfect analogy, I, um, for people to understand, like, you know, how, how much challenge to embrace. I mean, you're not trying to, um, you know, defrag the whole system [chuckles] yeah, you know? And, and, and I mentioned psychedelics. I, you know, I, I do think they have some interesting therapeutic potential. I, I also worry about, and I can tell you examples of people that got a... I guess now they- nowadays they call it one-shotted. They take ayahuasca a couple times, and they are forever different in ways that does not serve them.

    20. DE

      Wow.

    21. AH

      Those examples don't get talked about quite as often as-

    22. DE

      I'll bet

    23. AH

      ... the also many people who, uh, you know, um, seem to benefit from these things. So, um, plasticity, it seems, is not the goal. Directed plasticity is the goal.

    24. DE

      That's right, and it's very hard to direct. So I feel like, you know, let's imagine you could take some cocktail of, of neurotransmitters and get total plasticity of your brain. I don't think you'd want that. You wouldn't be you anymore. Who we are is the sum of our memories and the sum of our skills that we have built, and, you know, that keeps changing. We're always a moving target, um, and who you will be in five or 10 years will be different, but I don't think we'd want the plasticity of an infant, even though when you're doing, let's say, language learning, you say, "Oh, I wish I could learn this as well as I did when I was seven." But, uh, generally, it's not a state that you would desire, I think.

    25. AH

      If you're a regular listener of the Huberman Lab podcast, you've no doubt heard me talk about the vitamin mineral probiotic

  8. 38:50 – 39:41

    Sponsor: AG1

    1. AH

      drink AG1, and if you've been on the fence about it, now is an awesome time to give it a try. For the next few weeks, AG1 is giving away a full supplement package with your first subscription to AG1. They're giving away a free bottle of vitamin D3+K2, a bottle of omega-3 fish oil capsules, and a sample pack of the new sleep formula, AGZ, which, by the way, is now the only sleep supplement I take. It's fantastic. My sleep on AGZ is out-of-this-world good. AGZ is a drink, so it eliminates the need to take a lot of pills. It tastes great, and like I said, it has me sleeping incredibly well, waking up more refreshed than ever. I absolutely love it. Again, this is a limited time offer, so make sure to go to drinkag1.com/huberman to get started today. You've mentioned a few times future self. I think, uh, all of us are inherently interested

  9. 39:41 – 50:13

    Building a Better Future Self, Tool: Ulysses Contract to Avoid Bad Behaviors

    1. AH

      in our future selves and whether the things of our past, present, uh, and what we have control over going forward is going to put us in the best future self possible, right?

    2. DE

      Yeah.

    3. AH

      Humans love to optimize or fantasize about optimal, but how should we think about thinking about our future self?

    4. DE

      Yeah.

    5. AH

      Or should we not do that, right? Should we, should we, should we just avoid that loop-de-loop-

    6. DE

      No

    7. AH

      ... and, um, and, uh, get real stoic about it and just live in 10-minute time blocks or one-minute time blocks? It raises a really interesting question, I think, of, where should we set our time horizon-

    8. DE

      Mm

    9. AH

      ... to not just feel the best, but to be our best and to feel our best going forward?

    10. DE

      Yeah. Our capacity to think about our future selves is the most special part of being humans, and, you know, if we didn't do it, if we said, "I'm gonna be stoic about it," yeah, you'd eat the, the cupcake, and you'd do what- uh, like, all the things that wouldn't serve your future self.

    11. AH

      Or never eat the cupcake, like a real stoic, and then starve to death, right? [chuckles]

    12. DE

      [chuckles]

    13. AH

      Even if the cupcake were the only thing, right?

    14. DE

      [chuckles]

    15. AH

      What would the stoic do?

    16. DE

      That-

    17. AH

      Yeah

    18. DE

      ... that's right. So, um, yeah, we actually spend most of our time not in the here and now. We're reminiscing about the past, and we're simulating possible futures. Your, your mind is a movie theater, we're constantly thinking about where things are going, but this is great. This is what makes us able to do all the things that, that humans do successfully. And in our own lives, this matters so much because we're able to think about, "Who do I want to be?" Now, as you know, we've got this rivalry in the brain. You've got all these voices going on at the same time, all these different networks running. So, for example, if I put the cupcake down in front of you, um, you know, part of your brain wants to eat that. It's delicious. It's a rich energy source. Part of your brain says, "Don't eat it," you know, "I, I wanna stay fit." And so a part of your brain says, "Okay, maybe I'll eat part of it, uh, but I'll go to the gym later," or, "You know, I promised my girlfriend that I'll go do this thing." What- like, uh, we've got all these voices. You can cuss at yourself, you can cajole yourself, you can contract with yourself, and the question is, who's talking to whom? It's all you, but it's parts of you that have these different drives. Now, the part that's really amazing about us is we've got lots of short-term drives, but we also have this capacity to look into the future and think about who we want to be, and that is essentially subserved by our prefrontal cortex, which, as we mentioned earlier, is something that is a s- you know, the size of it is unique to humans. All of our closest cousins in the animal kingdom don't have a prefrontal cortex that's, uh, a fraction of what we have. That's what allows us to unhook from the here and now. Okay, now here's the thing: I have been fascinated by this for a long time, about how we sometimes know, "Okay, my future self is gonna act badly in this situation, so I'm gonna do something now so that my future self can't act badly." So this is the topic of my next book. It's called The Ulysses Contract, and where this term comes from is in the Odyssey, Odysseus, otherwise known as Ulysses, is coming home from the Trojan War, and he realizes that way up ahead, he's gonna pass the island of the Sirens, where you've got these beautiful female creatures who sing these songs that are so beautiful, it beggars the mind of the sailors, and, and everyone crashes into the rocks and dies. Ulysses really wants to hear the song, but he knows, like any mortal man, he's gonna fall for this and crash on the rocks. So what does he do? He has his men lash him to the mast so he can't move. He has them put beeswax in their ears so they can't do anything, and, and he tells them, "No matter what I do, no matter how much I'm screaming, just keep going. Just keep sailing."

    19. AH

      Smart.

    20. DE

      ... Right, it's smart, because what is happening is the Ulysses of sound mind is making a contract for the future Ulysses, who he knows is going to behave badly, so he's lashing him to the mast. And what I've been fascinated by is the ways that we do this in our lives all the time. So the example you gave a few minutes ago about locking up your phone in one of these lockboxes is a perfect example, because what you're making sure is that the Andrew of two hours from now can't do the wrong thing, 'cause you know he might. You know he's gonna be tempted, so you take away that temptation. By the way, I recently met, uh, an older gentleman who told me about an older woman that he'd met years ago, who used to take her money, her cash, and freeze it in a block of ice in the freezer so that she couldn't [laughs] spend the money-

    21. AH

      Oh, my goodness

    22. DE

      ... until she really needed it.

    23. AH

      Yeah, I don't have a money-spending thing, and I actually have pretty good control-

    24. DE

      Right

    25. AH

      ... uh, with, with the phone and with social media. For me, there's also a, I don't wanna call it a sick pleasure, there's a, uh, a bit of a pleasure in knowing that it's completely off-

    26. DE

      Yeah

    27. AH

      ... limits, because it means I can't even look at it for 10 seconds. I don't know-

    28. DE

      Yeah

    29. AH

      ... it, it, I think it involves something over control of, of things that I feel like are trying to control me-

    30. DE

      Yeah, exactly

  10. 50:13 – 56:57

    Brain Chatter, Aphantasia & Practice

    1. AH

      exchange, are, are kind of neurotic, right? They tend to overthink things.

    2. DE

      Mm.

    3. AH

      If they're gonna go running at 8:00 a.m. and it's 8:02, they're like, "I can't go because it's 8:02, not 8:00. I'll go at 9:00. Gotta do it on the hour," this kind of thing. And then I know people who are, like, you just do things, and you don't think about it as much, and they're good at suppressing that voice. Um, I think we assume that the, the chatter, the, the neurosis doesn't exist for them, but I think, um, I think it does. They're just better at saying, like, "Eh," like ignoring that inner voice.

    4. DE

      Yeah.

    5. AH

      Um, we're never trained how to do this.

    6. DE

      Right.

    7. AH

      We're never taught as kids, "Here's when you need to really think and deliberate, and here's when you just need to just do it."

    8. DE

      Yeah.

    9. AH

      And it's interesting to think about, okay, different career paths, different life requirements, and so forth, but, um, I feel like people fall into kinda two camps with this.

    10. DE

      Mm.

    11. AH

      Some people need to think and analyze less and do more, and some people [chuckles] actually need to, you know, probably still do but maybe think a little bit more about their behavior and reflect a bit more, and they would probably both say I'm crazy about this. Um, I won't tell you where I land. I think I'm kind of in the middle. No, I'm just kidding. [laughs]

    12. DE

      [laughs]

    13. AH

      Um, it, it depends on, on what's at hand-

    14. DE

      Yeah, yeah

    15. AH

      ... um, for, for most people, I think. Um, what do you think that's about, the ability to suppress the various versions of oneself or not?

    16. DE

      Yeah.

    17. AH

      The inner voice.

    18. DE

      Yeah, you know, I would say one of the most fascinating things we've discovered in neuroscience, t- for my money is, is just this issue that along anything we measure, there's a spectrum. So just take something like the internal voice. Uh, for my wife, for example, she describes it as her inner radio. She's always hearing her inner voice. I, I don't really have one. I just never hear that. So we're on opposite ends of the spectrum that way, but, you know, one of the things I've studied is, um, aphantasia all the way to hyperphantasia. That means when I... You know, if I ask you to visualize an ant crawling on a tablecloth towards a jar of-

    19. AH

      Mm

    20. DE

      ... purple jelly, some people see it like a movie in their head. That's called hyperphantasia. Some people have no picture at all in their head.

    21. AH

      Yeah.

    22. DE

      That's called aphantasia, and everywhere is, e- everyone is somewhere in between on the spectrum.

    23. AH

      What does the middle look like? So if I do that, if I... Maybe everyone can do this right now. It's a, a fun-

    24. DE

      Yeah

    25. AH

      ... experiment. If you're driving, don't close your eyes. [laughs]

    26. DE

      [laughs]

    27. AH

      Um, uh, I can see-

    28. DE

      Picture a sun coming over the mountain-

    29. AH

      Mm-hmm

    30. DE

      ... and the rays of the sun poking through the clouds.

  11. 56:57 – 1:00:50

    Specialization vs Diverse Experience, Childhood & Brain

    1. AH

      human evolution and the progress of building technologies, um, reflects the fact that people get siloed into, um, different tracks, and on the whole, that's advancing our species, right?

    2. DE

      Mm.

    3. AH

      You've got people that are hunter-gatherers, still very good at that, and building... And other people building weaponry, and other people building AI technologies, and that, that it would be, uh, detrimental to our species if everybody got sort of a core neuroplasticity training, learning how to do a little bit of everything, [chuckles] right? Um, or is the, the ch- what we see as chance actually part of the reasons why humans are the curators of the Earth, not just the prefrontal cortex, not just the extended window of plasticity-

    4. DE

      Mm

    5. AH

      ... but how we are afforded different opportunities to work with that plasticity?

    6. DE

      Yeah. I'd say a couple things. One is, we're clearly predisposed to particular things, and so, for example, I'd like to be a swimmer as good as Michael Phelps, but I just don't have the wingspan that he does. He's got, like, I don't know, seven feet between his fingertips or something.

    7. AH

      Geez.

    8. DE

      I- there's no way I'm gonna be able to be as good as he is. Um, that's a genetic thing that he drops in the world with, that I don't. Fine. Um, so given that people are off on different trajectories anyway, the way I think about this, I don't know how this will translate just in terms of audio, but like a space-time cone in physics is where you start in one spot, and then there are all these different trajectories you can take into the future. Picture this like you're starting at the bottom of the ice cream cone, and you can, y- you can take any different trajectory as long as it still exists within the ice cream cone. Okay, so, um, uh, you know, we drop into the world with our genetic skills and predispositions. We have childhoods that we don't choose. We're born into a cultural, language, and era that we don't choose, and that defines the limits of the ice cream cone, about where we can go with that. As far as specialization goes, you know, economists will argue this is part of what makes a very healthy society, is that, you know, some people become the lumberjacks, and some the lawyers, and some the accountants, and whatever. Um, you know, I do feel like we're in a really great era, though, in general, in humankind, where kids do get very broad educations, and they're sort of encouraged to try everything. And spend a few years in karate and in soccer and in piano lessons, and so on. That's wonderful. So the... My father was a psychiatrist, and he always said, "Really, the whole job of a parent is just to open doors for the child. That's it." So you give the child all these lessons, you open all these doors, and then the kid takes their own path, depending on, you know, this extraordinarily complicated formula of things that we'll never understand, but they go through one door and not the others. Kierkegaard said, "Every man starts as a thousand men and dies as one," and what he meant, of course, was that you start with all this potent- you could do all, you could have been a great saxophonist or whatever-

    9. AH

      Yeah

    10. DE

      ... but you're gonna die having done exactly what you did and, and not the other path. So what, what's weird about life is that, yeah, every door that you choose, some others close as a result.

    11. AH

      Kierkegaard, uh, seemingly understood that the nervous system start, starts out hyper-wired-

    12. DE

      Yeah

    13. AH

      ... and then a lot of learning is the pruning back of connections and strengthening of the remaining ones.

    14. DE

      That's exactly right. Exactly right. You know, uh, so, uh, as you of course know, the, the brain starts out... You've got essentially a fixed number of neurons. There's some debate about whether there's a few new neurons born in humans or not. Put that aside. What happens is, over the first two years, those neurons connect more and more and more and more, and what you end up getting is this hyper-connection by the time you're two years old, and from there, it's just a matter of pruning an overgrown garden, and that's all that's happening. And, and the way the pruning happens is based on what you're experiencing in the world. The world is what prunes your garden and strengthens particular paths and lets other paths go.

    15. AH

      As a bridge, perhaps between plasticity and time perception, which we've been sort

  12. 1:00:50 – 1:06:17

    Space & Time Perception, Tool: Space-Time Bridging Meditation

    1. AH

      of doing already, uh, I have this, um, practice that I've been doing for a few years, um, in hopes that it's beneficial for something, and I'd just like your thoughts on it. Um, I'm not looking for approval here, uh, it, r- truly, but here's the idea. I was struck by the somewhat obvious thing that, you know, we can close our eyes, uh, focus on our interoception, our skin, our breathing. We can meditate, bring our awareness, you know, into the, quote, unquote, "present." The breathing is seems like a good way to do that. Um, or we can open our eyes, and we can focus on something some distance away, or we can imagine the pale blue dot, and we're just this little thing running around on this pale blue dot. And, you know, when we move through those different, uh, realms of space, not just outer space, but from body to out of- outside our body to outer space, there's a different time association with each of those, and I'd like your thoughts on that.

    2. DE

      Yeah.

    3. AH

      And I j- I just started devoting a, a little bit of time to stepping from one of these to another and just spending some time trying to, uh, think and exist in the different time domains-

    4. DE

      Yeah

    5. AH

      ... um, in my head. And so I'll do that maybe for two, three minutes or four minutes or five minutes, and I told myself, and I still tell myself, that it affords me some flexibility when something's happening in the moment, and you wanna get perspective. It's about getting out of that time domain and realizing this isn't gonna go on forever, even though it feels like it.

    6. DE

      Yeah.

    7. AH

      So I developed this as a bit of a practice for myself-

    8. DE

      Nice

    9. AH

      ... um, because I f- I felt like it's just a, it's not a meditation, it's a perceptual exercise.

    10. DE

      Yeah.

    11. AH

      Um, so what I'm-... curious about is the relationship between time perception and where we place our attention. That's the first question. And then, you know, maybe what we can do with this, or, or could we evolve this, uh, perceptual exercise so that, um, I, and, and others perhaps, if they want to, can start to access different, um, space-time representations, which sounds so fancy-

    12. DE

      Yeah

    13. AH

      ... but it's really just a way of, like, getting outside yourself or getting within yourself. Sorry if I'm being, um, choppy here, but, but this is something that's, it feels very important, and-

    14. DE

      I, I love that. I think that's brilliant. Um, one of the things that is so striking about time perception is that you don't have a single part of the brain that deals with that. You actually have different mechanisms that deal with thinking about long eras of time, and seconds, and subseconds. Um, totally different mechanisms going on here. Uh, and, and we can demonstrate this in the laboratory. So time perception's something I've been studying since graduate school, and, um, y- you know, I'm happy to say I've got papers in Science and Nature, and, you know, the top journals on this topic. Why? Because it's such a weird thing that's so understudied, about how- why, why we perceive time the way we do. So, um, let me say a few things about it. One is that it is a... These longer timescales, what you're referring to, thinking about being, uh, far away in space and time, this is a cognitive development. Children can't do this well, and they learn better and better. So for example, if you talk to a, a, a seventh grader, and you talk about the Roman Empire and what was happening 2,200 years ago, it's re- they- it doesn't mean anything. You know, it's like, "Okay, so that's the past," and whatever. But as you get older, if you become, let's say, a professional historian, you get better and better at understanding that. Why? Because you've lived decades, and so now you can sort of think, you can sort of feel what a century might look like-

    15. AH

      Mm

    16. DE

      ... and you can sort of, with practice, get better at, at these things. But the point is, that is something we learn how to do, both in space and time. Obviously, when you're an infant in the crib, space is just a really close thing, and eventually-

    17. AH

      It's your whole world.

    18. DE

      It's your whole world.

    19. AH

      Mm-hmm.

    20. DE

      But eventually, you get outside, and you look down long highways in Utah, and you, you, you really start getting a better sense of this. Um, y- I, I, uh, to my knowledge, there's no data on, on what it would be to s- to sort of throw yourself back and forth between these different space-time, uh, scales. I love it, though. One of the classes I teach at Stanford is called The Brain and Literature. Uh, I've always been a lover of literature, and one of the things that I love is when authors do exactly this, where they, they zoom in on something really tight, and they're really paying attention, and then they zoom way out. That is the most extraordinary sort of feeling. Um, so anyway, I commend you on coming up with that-

    21. AH

      Mm

    22. DE

      ... version of space-time meditation or whatever it is.

    23. AH

      Yeah.

    24. DE

      That's very smart.

    25. AH

      Yeah, well, it was, um, it was born out of this thing, you know, the, the Viktor Frankl thing, like between stimulus and response, you know? And but there's something about the autonomic nervous system, like when we're in a heightened state of stress, um, we're not good at getting outside of the moment. You know, people are like-

    26. DE

      Yeah

    27. AH

      ... "Take 10 breaths," or whatever, and it wasn't that I was having struggles with that. I just thought, it's so interesting, like, you watch a movie, and it seems to be placed in a different time domain in each scene.

    28. DE

      Yeah.

    29. AH

      Or, um, and, you know, then you go for a walk or a hike, and I, I have this obsession with the idea that when we see horizons, we have a different time perception than when we, uh, can't see horizons.

    30. DE

      Yeah.

  13. 1:06:17 – 1:11:23

    Are We Good at Estimating Time?; Fear, Time & Memory

    1. AH

      Um, how good are people at perceiving time, and, um, why am I always late? [laughing]

    2. DE

      [laughing] The why are you always late, that has to do with the Ulysses contract thing, which is just... It, it requires a commitment to say, "I'm gonna be the kind of guy who's always on time," and the way to do that is to say, "I'm gonna commit to always being five minutes early." So you get to a place early, and you just hang out in your car, and you, you know, uh, take care of some texts or whatever. That's the way to be always on time.

    3. AH

      Interesting.

    4. DE

      Okay, but are people good at perceiving time? No, we're actually quite terrible at it. Um, and some people are better than others, but one of the lessons that's emerged from my research on this stuff is that a lot of time is, is illusory. Um, so you, you may know I did this experiment years ago. I was very interested in this question of, does time run in slow motion when you're in fear for your life? Because when I was a child, I fell off of a roof of a house. I almost died. I landed on my... I, I landed in a push-up position and busted my nose so badly that they had to remove all the cartilage and so on.

    5. AH

      Whoa!

    6. DE

      And I've had a terrible sense of smell ever since because I busted the crim- cribriform plate and everything. But the part that interested me, even as a child, was that the whole fall seemed to take so long. It felt like, oh, my God, that was this really long thing. Obviously, I was totally calm during it. I was thinking about Alice in Wonderland as I was falling and how this must have been what it was like for her to fall down the rabbit hole. Um, this is typical-

    7. AH

      How old were you? Sorry.

    8. DE

      I was eight years old.

    9. AH

      Wow.

    10. DE

      And this is typical when people are in life-threatening situations, is that there's a sense of total calmness and bizarre thought, but also it seems to have taken a long time. You know, people report this all the time when they're in car accidents. They say, "Oh, I, I watched the hood crumple and the rearview mirror fall off, and I was looking at the face of the other guy," and whatever. People experience this in gunfights, like police officers and so on. Everything seems to take a longer time. What happened is, when I grew up and became a neuroscientist, I realized no one had ever studied that, and I got really curious about, is it the case that time seems to run in slow motion-... while you're experiencing it, or is it a trick of memory somehow? So I ran what, to my knowledge, are still the only experiments that have ever been done on this. Do you know about this? So-

    11. AH

      Yes and no.

    12. DE

      Great.

    13. AH

      Yes, I'm familiar with the paper. No, I've never heard it this way, so keep going.

    14. DE

      Okay, great!

    15. AH

      Yeah, yeah.

    16. DE

      So what I did is I rounded up 23 volunteer subjects, and I dropped them from a 150-foot-tall tower in free fall backwards, and they're caught by a net below going 70 miles an hour.

    17. AH

      I wanna be in your experiments.

    18. DE

      Yeah, y- yeah, you would've loved this. It's a re- but it's terrifying. I did it myself three times first to make sure it was all running, and it's equally terrifying all three times 'cause you're falling backwards. Okay, what I did is I then built a device. My students and I built this device. It fits on people's wrist, and it flashes information at them in such a way that we could measure the speed at which they're taking in information. Essentially, we're taking, uh, we're taking advantage of what's called flicker fusion frequency, where we're flashing lights really quickly, and you can see that at a certain rate of lights, you can see exactly what's going on, and just faster than that alternation rate, you can't see anything. Okay, so we drop people, we had them read the numbers on the wristband, and we're finding out, are people actually seeing in slow motion during a life-threatening situation? This is on 23 people. The results were very clear. People do not see any faster in a, a life-threatening situation, and yet, when we ask people retrospectively with a stopwatch to judge how long their fall was versus watching someone else do the fall, their own fall felt much longer to them. Okay, turns out this is all a trick of memory, which is to say, when you're in a life-threatening situation, you recruit not just your, uh, hippocampus for laying down memory, but a, a secondary memory track, mediated by the amygdala. You're- you've got this emergency control center, and you're writing down memories in this other secondary track. When you read that back out, you say, "What just happened? What just happened?" You've got all this density of memory that you don't normally have 'cause you've written down every detail. So your brain says, "Oh, my gosh, this is what happened, and the hood crumpled," and so on. Um, but it's because all we're ever conscious of is our memory of an event, as in what happened during the event. So when you're in a life-threatening situation, you write more down, you think it took longer, um, to, uh, to transpire. And by the way, this issue about memory equals time explains a lot of things. For example, the issue of when you're a child and a summertime seems to take forever, and then by the time you're our age, the summertime seems to disappear. It's because, as a child, you're figuring out the world. You're writing down lots and lots of memory during that summer. "Oh, this is the first time I ever saw a waterfall and went hiking here and did this thing." But by the time you're our age, you've sort of seen all the patterns before, and so what we're... You know, when we look back at a summer, we don't have much new footage to sort of anchor on. So we say, "Oh, well, it was the winter, now it's the fall. Okay, fine, I guess that was really fast."

    19. AH

      Amazing.

    20. DE

      So this is why time speeds up as we s- as we grow older.

    21. AH

      Glucose is a key player in how our body functions, not just in the long term,

  14. 1:11:23 – 1:12:53

    Sponsor: Lingo

    1. AH

      but in every moment of our lives. That's because it is the major fuel for our cells, especially our brain cells. Glucose directly impacts our brain function, mood, and energy levels, and it may even affect our levels of tenacity and willpower. This is why I use the continuous glucose monitor from Lingo. I absolutely love it, and I'm thrilled to have them as a sponsor of the podcast. Lingo helps me track my glucose in real time to see how the foods I eat and the actions I take impact my glucose. When glucose in your body spikes or crashes, your cognitive and physical performance do, too. In fact, large glucose peaks and valleys lead to brain fog, fatigue, irritability, and hunger. What you eat, of course, plays a major role in your glucose. Some foods cause sharp spikes and big crashes, and others do not. But not everyone is the same in terms of how they respond to particular foods. Seeing your glucose in real time helps you build eating and other habits that support metabolic health, mental clarity, and sustained energy. Lingo has helped me to better understand what foods to eat, when to eat, and how things like a brief walk after a meal can help keep my glucose stable and much more. If you'd like to try Lingo, Lingo is offering Huberman Podcast listeners in the US ten percent off a four-week Lingo plan. Terms and conditions apply. Visit hellolingo.com/huberman for more information. The Lingo glucose system is for users 18 and older, not on insulin. It is not intended for the diagnosis of diseases, including diabetes. Individual responses may vary. I mean, I feel like these are- what you're covering today is, uh, like, the, the

  15. 1:12:53 – 1:18:56

    Fearful Situations & Time Perception; Joyful Events & Novelty, Tool: Do Things Differently

    1. AH

      most interesting things about life and experience. I have a question about, um, [lips smack] the fall experiment.

    2. DE

      Yeah.

    3. AH

      Is it accurate to say that your perceptual frame rate during a highly stressful experience is not different?

    4. DE

      Is no different.

    5. AH

      You're not taking, uh, a, um, [lips smack] higher frame rate movie-

    6. DE

      Yeah

    7. AH

      ... okay, which is h- more frame rate is how they generate slow motion, for instance. Makes sense-

    8. DE

      Yes, exactly

    9. AH

      ... like as opposed to strobe frame rate, or, uh, you know, ep- just, right? Um, but that in some sense, your unconscious frame rate is because the amygdala is tracking more information than you normally would have a- have access to in, say, a calm, everyday experience, and so the memory is higher frame rate, but the experience is not.

    10. DE

      You know, uh, yeah, it's really close. I wouldn't say... I wouldn't use the term frame rate in there. It's just that you have y- under normal circumstances, you write down almost nothing. You just, everything's passing through you, you're not really remembering much. But in an emergency situation, your amygdala, being the emergency control center, says, "Everybody stop what you're doing. This is the most important thing going on. Everyone pay attention to this." So you're noticing every detail, and you're not used to that. So just for anyone who knows what I'm referring to here as a Bayesian issue, um, y- you know, y- y- your brain thinks, "Okay, a certain amount of memory must equal a certain amount of time." Now, you've got just a lot more detail, and so it says, "Oh, well, that must have been, you know, six seconds or something." I... What I did, by the way, I collected hundreds and hundreds of subjective reports from people who had been in accidents of various sorts. You know, this guy got in a motorcycle accident and had, you know, come off the motorcycle and had turned over and over and over on the road, and he said as he was rolling over and over, he was, like, composing a little ditty in his head, like a little song to the-

    11. AH

      Mm

    12. DE

      ... sound of his helmet hitting the road and so on, 'cause this is the kind of bizarre thought-

    13. AH

      Mm-hmm

    14. DE

      ... that people have. But it seemed to have taken a long time, and when he saw [chuckles] footage of it afterwards, you know, the whole thing took, whatever, a second or two, but it seemed to him to have taken six seconds.... but again, it's in retrospect when he's thinking, "What, what happened? What was the event like?" Um, by the way, I'll just mention, after I published this paper, sometimes people would come up to me after a talk and say, "I know that's not true, because I was in a car accident, and I know it took a long time." And I said, "Okay, look, the, the person on the passenger seat next to you who was screaming, 'No!' Did they- did it actually sound like they were saying, 'Nooo?' Because if time were running in slow motion, that has to be the consequence-

    15. AH

      Mm-hmm

    16. DE

      ... that everything is spread out." And they had to, uh, allow that it didn't sound like sounds were distorted, and so on. So, um, it is really about having more, a higher density of memory.

    17. AH

      Super interesting. What about for non-stressful, non-life-threatening circumstances? Like, let's pick a, a purely happy event.

    18. DE

      Yes, yes.

    19. AH

      One would hope, day of one's wedding. Um-

    20. DE

      Yeah.

    21. AH

      You know, I was about to say birth of a child, but depending on how, you know, who's doing the majority of the work, and how stressful it was. I mean, of course, the birth of a healthy child is a super wonderful event, but it can be very stressful, too-

    22. DE

      Yeah

    23. AH

      ... under certain circumstances. So let's pick something purely happy, right?

    24. DE

      Yeah.

    25. AH

      Uh, a terrific wedding, a great party, maybe a vacation with your spouse or family, where it just is, like, bliss day.

    26. DE

      Yeah.

    27. AH

      Are you clocking more experiences?

    28. DE

      So any time you're doing something novel, and this actually ties back to the conversation we had before about seeking novelty, whenever you're doing something novel, you're writing down more memory, and that's the whole key. So, for example, if you spent your last weekend going off and doing something wacky that you've never done before, parasailing into, over sharks or whatever the thing is, you'd come back and you'd think, "Wow, it seems like it was so long since Friday. Now, it's Monday, and it's been forever since I was back in the studio." But if you have a normal weekend, where you're not doing much of anything but surfing Instagram or something, then you come back and you think, "God, it was just Friday." The difference is just how much memory you clocked, and therefore, what you can draw on in terms of footage. Um, I, I actually think this happens with drugs, where people, you know, people sometimes have the experience on marijuana where they think, "Wow, I've been standing here forever," and it's because they're having a hard time a- anchoring down on footage about, like, "When did I arrive to the kitchen? When... What happened since I've been here?" And so they just [chuckles] they don't know. But, uh, anyway, the point is, sometimes people have this idea about time speeding up as you get older. They say, "Well, you know, to an, to an eight-year-old, a summer is this frac- big fraction of their life. But to a 50-year-old, it's a, it's a smaller fraction," but I don't think that's it at all. It's that... It's, it's what you did this past weekend can make the weekend seem longer. When it comes to some great new event, like the birth of a child or a wedding, or whatever it is, it has to do with how much attention you're paying and how much memory you're writing down, and that means it is, to some degree, in our control. If we really attend to things and write down memories instead of letting life just wash over us, we can seem as though we've lived longer. I'm not talking about longevity, I'm just talking about making it seeming as though you've lived longer, which is... Look, here's, here's something that I try to do all the time, is just switch stuff up. For example, brushing your teeth with your other hand. Not hard to do, but it's just one of a million ways of knocking yourself off a path. One thing I try to do every time I drive home from Stanford, is I try to take a different drive home, a different route home. You know, wastes an extra minute, uh, whatever, but it's... I'm seeing new things. I'm observing new things about the neighborhood or whatever, that I hadn't noticed before. One thing that's very easy to do is just rearrange your office, like push your desk over here. Take two paintings and just swap them on the wall. All this stuff is super easy, but it really matters. It's important, because what it's doing is enhancing brain plasticity in the sense of just challenge- You know, your, your internal model says, "Okay, I've got, I've got this world," and then suddenly it says, "Oh, there's something new. There's something interesting going on in this world." And it makes it seem as though you've lived longer, because you're writing down more memories about everything.

    29. AH

      Gosh, uh, this time perception thing, uh, I spend way too much time

  16. 1:18:56 – 1:27:09

    Staying in the Present, Mental Illness & Time Domains, Addiction

    1. AH

      thinking about it, and, um, and I'm still trying to wrap my, my head around how much time we should spend trying to be present. So I have a, a... And this is not an official definition, but my kind of, um, understanding of the dopamine system and addiction, as I say, uh, and people have heard me say before, you know, a- addiction is a progressive narrowing of the things that bring you pleasure.

    2. DE

      Mm.

    3. AH

      It also involves continued use or, uh, or behavior despite negative consequences. But, but, but I mention the other definition of addiction, uh, progressive narrowing of the things that bring you pleasure, because I was trying to come up with some, um, at least semi... At least accurate, if not ex- but not exhaustive definition of kind of like enlightenment, when people talk about enlightenment, right?

    4. DE

      Mm-hmm.

    5. AH

      All these monks who are so, get so present through all this meditation, or people go to Big Sur, and they get, you know, they're so present, present, present, enlightenment. I think of an, one definition might be, okay, I'm not the authority on this, but might be a progressive expansion of the things-

    6. DE

      Mm

    7. AH

      ... that bring you pleasure. But to-

    8. DE

      Mm-hmm

    9. AH

      ... really get pleasure out of a sip of water, I'm not terribly thirsty right now. If I take a sip of water, it doesn't taste anything like if I were very thirsty, but we need to pay attention.

    10. DE

      Yeah.

    11. AH

      We need to be in the pre... What is v- paying attention? It's being, most of the time, in the present, right?

    12. DE

      Yeah.

    13. AH

      Paying attention to these things. But w- if we spend all our time in the present, we, um, we eliminate Ulysses contract.

    14. DE

      Yeah.

    15. AH

      So the extremes can't be good, but I think i- examining the extremes, like the free-fall experiment, they're useful, uh, windows into time perception and how, and how we measure life.

    16. DE

      It could be that by establishing Ulysses contracts in many aspects of our lives, we get more of an opportunity to be in the present. 'Cause we know, "Look, I don't have to worry about my future self. I'm not gonna eat that cookie. I am gonna go to the gym, whatever, 'cause I've already set up these contracts. I don't have any cookies in my house. I'm meeting my buddy at the gym," whatever. Then you have more of an opportunity to be in the present. Um, you don't have to simulate all kinds of futures. Um, yeah, I think paying attention to things matters a lot, but we have to be smart about what we pay attention to. I mean, it might be lovely to really love the water and so on, but not, you know, your Instagram feed or something. So it's just a matter of, uh, uh-... of thinking clearly about what you want to pay attention to and devote your memories to.

    17. AH

      Yeah.

    18. DE

      And this, this translates into what you set up. Like, I'm gonna set up a dinner at my house, I'm gonna invite my close friends, and I'm gonna have this dinner and pay 100% attention to this dinner. I'm gonna be present at this thing, 'cause that's the stuff of life.

    19. AH

      Mm-hmm. Where I'm getting to with this is that there's, um, beauty and there's tragedy at every spatial scale-

    20. DE

      Yeah

    21. AH

      ... and every temporal scale, right? I- unfortunately, in my neighborhood, you know, this issue has not been resolved, um, in many places. You know, we have a, we have a homelessness, and drug addicted, and mental illness population, and those intersect i- in very complicated ways. That is so extreme that you can see people who are, um, paying immense amount of attention to what anyone else would consider trivial, like the, the-

    22. DE

      Yeah

    23. AH

      ... you know, bits of dirt in the, on the sidewalk, and the so... And we- and it's so tragic, right? We can see that that's not a, a good use of one's time, attention, and focus, right?

    24. DE

      Yeah.

    25. AH

      But there's also beauty at all sorts of scales, right? I mean, the- I think one of the obsessions that people have with, like, fractals and, and, you know, these, um, uh, organization a, at very small scales all the way up to very large scales is it, it brings us to this, like, relationship with life. Like, there's all this stuff we can't see, and it's beauty at every scale, tragedy at every scale, right?

    26. DE

      Yeah.

    27. AH

      I mean, p- there... I don't even have to mention a tragedy at, at massive scale, because they're all over the world, and they have been throughout human history, frankly.

    28. DE

      By the way, I was just, I was just in Las Vegas at CES, uh, giving a talk yesterday, and as I was leaving, I looked out the window, and there was, uh, you know, this, uh, Chinese lion statue, and there was this homeless woman smoking a cigarette, and she was rubbing this thing very vigorously. And the guy driving the car told me, "Oh, that's good luck if you [chuckles] rub the statue." [chuckles]

    29. AH

      Okay.

    30. DE

      Which is, of course, ridiculous. But the woman was rubbing and rubbing and ru- We're at a red light, and I watched her for, you know, like, 60 seconds doing this, and yeah, and it was tragic to me. Because her brain has set up an association, which is, "If I do this action, there will be this result."

  17. 1:27:09 – 1:30:51

    Social Media, Addiction, Curiosity

    1. AH

      people-

    2. DE

      But we all will

    3. AH

      ... uh, at some point, um, or, uh, or a pet or, or both. Um, do you think that, uh, constant engagement in, um, let's just say, like, TikTok-... type social media, where the, um, upregulates the quote-unquote, "receptors" or of expectation for it, that make it harder for people to-

    4. DE

      I understand

    5. AH

      ... to stop using it. Because the, the drug, uh, and addiction definition you gave, which I love, um, you know, dopamine receptors for methamphetamine or for cocaine, or, uh, and so on. But, uh, for an experience, for gambling, for social media, um, the, the receptors become more like circuit activations, or like the circuits of the brain anticipate it, and if they don't get it, do you think that there's a, a kind of a withdrawal-like effect?

    6. DE

      I don't know how I feel about this. I wonder, when we were growing up, people said, "Oh, it's the television. It's the television's ruining everyone's attention span," and so on.

    7. AH

      It'll rot your brain, I remember.

    8. DE

      It'll rot your brain, exactly.

    9. AH

      My mom would kick us out.

    10. DE

      Yeah.

    11. AH

      This was just very common. She'd say, "You've gotta go outside." She would lock us out of the house.

    12. DE

      Exactly.

    13. AH

      We weren't allowed back in. She said, "Don't come back until, until dark."

    14. DE

      Yes, exactly!

    15. AH

      We, we did not have the option to watch cartoons or to... for more than a couple minutes-

    16. DE

      Right

    17. AH

      ... after school. We were forbidden.

    18. DE

      Right.

    19. AH

      So she could get peace, and we could get activity.

    20. DE

      Exactly.

    21. AH

      Yeah.

    22. DE

      And younger people might not know, the television was called the boob tube-

    23. AH

      Mm-hmm

    24. DE

      ... where a boob was like an idiot.

    25. AH

      Mm-hmm.

    26. DE

      And that was the idea. That's where the term YouTube, you know, was a funny, uh, derivation of that. But the um... Right. So now what kids are watching is lots of content. We're all watching lots of content on Instagram, TikTok, much of which is great. It's well-produced, it's matched to our interests, and so I, I don't- You know, are we addicted? Yes. Is it an addiction because it's offering better content than many other things in our life? In some sense, yes. So I'm a little torn on it. The other thing that we've all noticed, though, is that people don't seem to be happy when they spend time scrolling on it. They're kind of tempted to do it, but when they finish, they never feel like, "Wow, that was really a great experience!" Um, they're kinda drained from it. So in that sense, it has the characteristics of an addiction, where you keep going back to it even though you're not getting the high from it that you did the first time.

    27. AH

      I will say, um, as long as I use it properly, I f- I love social media and YouTube. I'm not just saying that as a political [chuckles] statement.

    28. DE

      [laughs]

    29. AH

      I teach on YouTube, I learn from you, I learn from others. Like, the other day, I wanted to, um, learn about architecture.

    30. DE

      Yeah.

  18. 1:30:51 – 1:35:26

    Vision & Auditory Deficits, Sensory Substitution, Neosensory Wristband

    1. DE

      sold six months ago, so I don't have it anymore. Just-

    2. AH

      Oh, okay.

    3. DE

      Yeah.

    4. AH

      All right.

    5. DE

      So, had a company, yeah.

    6. AH

      Congratulations.

    7. DE

      Thank you.

    8. AH

      But Neosensory was a really neat idea of combining different senses, um, people wearing bracelets so they could feel sounds and, um, and so forth. Um, can anyone do this, even if they're not deficient in vision or in hearing, um, or in some other modality?

    9. DE

      Yeah, so I got- I just got really interested in this topic about pushing information into the brain via unusual sensory channels. So, for example, as you referenced, I, you know, I built a, a wristband that captures sound and turns sound into patterns of vibration on the skin. This is for people who are deaf, and deaf people could learn how to hear that way. Why? Because this is the same thing that your inner ear, your cochlea, does. It's just capturing vibrations on the eardrum and translate- breaking that up into different frequencies, shipping it off to the brain in terms of spikes, just these, you know, voltage spikes along nerves. Um, we're doing the same thing, except we're pushing it in through the skin. It goes up the spinal cord to a different part of the brain, but the brain can figure that out. How? Because it's doing correlations. It sees somebody's mouth move, it's feeling the sound, and it figures out how to hear that way. Now, this idea of sensory substitution, um, I, you know, I wish I'd invented that, but it actually has a long history. The more I researched, I found out it goes back to the 1800s, um, when people first started asking, "Hey, can you push information into the brain in a w- weird way?" So the very first one was in the 1880s. Um, they had a little, uh, a little camera lens that would just detect light and dark, and it would get translated into a buzzing on your forehead. And, um, uh, for people who were blind, they could tell, you know, "Okay, well, there's, there's a wall over here, and then there's an opening over here," and so on. And then people worked on this. The first major paper was in 1969 in Nature. A guy named Paul Bach-y-rita took blind people, and he put them in a dental chair, and he had this thing that would poke them in the back, a grid of 40 by 40 little solenoids that would poke you in the back. And he set up a video camera, and whatever the camera saw, you would feel that in your back. So if it's looking at a triangle, [pops] you feel that triangle poked in your back. If it's looking at a face, you feel the face... So blind people got pretty good at doing this, especially once he let them control the camera so they could move the camera any way they wanted.

    10. AH

      Mm.

    11. DE

      People got really good at being able to tell what was going on.

    12. AH

      So it was following them around as they moved through the world?

    13. DE

      No, they were sitting in this dental chair.

    14. AH

      Mm-hmm. Mm-hmm.

    15. DE

      Um, and, and that's exactly it. In 1969, the technology was really clunky and heavy and got hot and whatever, and there was no way to make it portable in a meaningful way. But as time has gone on, we've been able to do that now. And so Paul Bach-y-rita's research, he passed away some years ago, but his research has continued, and-... with something called the BrainPort, which is, again, for blind people. So with the BrainPort, the way this works is you're wearing this little camera on your head on glasses, and you've got this, uh, little electrical grid on your tongue. And so whatever the camera is seeing, y- you feel that on your tongue. It feels like pop rocks. So if I'm looking at the coffee cup in front of me, I'm feeling the outline of the coffee cup, and blind people can get so good at this, they can do things like, you know, throw a ball into a basket or navigate a complex obstacle course.

    16. AH

      Whoa!

    17. DE

      It sounds crazy, but the thing to remember is the way you normally see is your eyeballs are, you know, these, these devices embedded in your skull here that are capturing photons and turning that into spikes that race into the darkness of your brain.

    18. AH

      Electrical signals.

    19. DE

      Electrical signals, exactly. And so this is just turning what your tongue is feeling into spikes, these electrical signals that race into the darkness of your brain, and you can figure it out. You can learn how to see that way. And again, it's with correlation, 'cause you feel something with your fingers, maybe you hear something also, and so you're putting that together, and your brain says, "Oh, okay, I got it. There's a visual thing out there in the world." A- and the really wacky part, I'll just mention, is that people using the BrainPort who, let's say, used to have sight and lost it, they will report it is like sight. They say, "I remember seeing, and this is like seeing," even though it's coming in through their tongue! And with the Neosensory wristband that we built, um, you know, I interviewed a guy after he'd been wearing it about six months, and I said, "Look, when you hear a dog bark, do you feel the buzzing on your wrist, and then you think, 'Okay, that must be a dog barking?'" He said, "No, no, I hear the dog bark out there," which sounds crazy, but obviously, that's the same crazy thing happening with our ears. You know, we've got this whole mechanism going on that we're very used to, and so we say, "Oh, of course the dog is out there," but in fact, it's all happening in here in the darkness of the skull.

    20. AH

      I'd like to take a quick break and acknowledge one of our sponsors, Function. Last year, I became

  19. 1:35:26 – 1:37:13

    Sponsor: Function

    1. AH

      a Function member after searching for the most comprehensive approach to lab testing. Function provides over 100 advanced lab tests that give you a key snapshot of your entire bodily health. This snapshot offers you with insights on your heart health, hormone health, immune functioning, nutrient levels, and much more. They've also recently added tests for toxins, such as BPA exposure from harmful plastics, and tests for PFAS, or forever chemicals. Function not only provides testing of over 100 biomarkers key to your physical and mental health, but it also analyzes these results and provides insights from top doctors who are expert in the relevant areas. For example, in one of my first tests with Function, I learned that I had elevated levels of mercury in my blood. Function not only helped me detect that, but offered insights into how best to reduce my mercury levels, which included limiting my tuna consumption, I'd been eating a lot of tuna, while also making an effort to eat more leafy greens and supplementing with NAC and acetylcysteine, both of which can support glutathione production and detoxification. And I should say, by taking a second Function test, that approach worked. Comprehensive blood testing is vitally important. There are so many things related to your mental and physical health that can only be detected in a blood test. The problem is, blood testing has always been very expensive and complicated. In contrast, I've been super impressed by Function's simplicity and at the level of cost. It is very affordable. As a consequence, I decided to join their scientific advisory board, and I'm thrilled that they're sponsoring the podcast. If you'd like to try Function, you can go to functionhealth.com/huberman. Function currently has a wait list of over 250,000 people, but they're offering early access to Huberman Podcast listeners. Again, that's functionhealth.com/huberman to get early access to Function. Recently, I've been, um, listening to a book that I read previously, which, uh, I love. By the way,

  20. 1:37:13 – 1:41:36

    Sensory Reliance, Echolocation, Potato Head Theory, Sensory Addition

    1. AH

      I love Livewire.

    2. DE

      Thank you.

    3. AH

      I'm not just saying that. I've, I've, you know, read it, like, three times, um-

    4. DE

      Thank you

    5. AH

      ... when it came out. I need to revisit it. I like to reread books.

    6. DE

      Yeah.

    7. AH

      I believe in rereading books. Um, Ed Yong, uh, wrote a book called An Immense World. Um, he's not a scientist, but he's a science writer, and it's about different, um, sensory modalities that different animals use.

    8. DE

      Yeah.

    9. AH

      And for an animal lover like me, it's a, uh... I found it really spectacular. But he, he says something that I totally agree with, which is that we shouldn't think so much about whether or not, um, a given animal is good at smell and bad at vision, or really good hearing, or b- the valuations of these things are really tough. With visual acuity, we can do it, like, you know, an eagle, eagle resolution and, you know, versus human resolution. But when it comes to things like smell or touch, the better question, uh, he says, and I agree, is, um, how much does a given organism or person rely on a given sense will tell you sort of their abilities with that sense.

    10. DE

      Mm.

    11. AH

      I mean, there's some bounds on that, right?

    12. DE

      Yeah.

    13. AH

      I, I can't echolocate like a bat, but I'm guessing that if I had to, in order to navigate an environment, I could learn to echolocate, and I think there are, there are individuals who have learned to echolocate.

    14. DE

      Exactly. In fact, the term was coined in 1930 in a science paper this gentleman wrote called "Echolocation in Bats and Blind Men." And, uh, uh, blind people, since at le- almost 100 years now, can do this thing where they use clicks of their tongue or the tap of their cane or any kind of sound that they make, and they listen very carefully for what's bouncing back to them, and they can echolocate. It also turns out that seeing people can echolocate if it is relevant to them. You know, if you really wanna put the effort into it, you can learn how to do it. Again, this just points to the plasticity of the brain, how, how good it is at doing this. Some years ago, I suggested this Mr. Potato Head theory about thinking about the brain, which is whatever senses you plug in to a brain, it'll figure out what to do with that information. And so when we look across the animal kingdom, we find all kinds of very weird stuff, not only, you know, eagle eyes and so on, but we find, um, you know, many animals, like, let's say, snakes, they pick up on infrared range of vision, which, which is, uh, invisible to us. Um, you've got lots of fish that pick up on perturbations in electrical fields. They have electroreception. Um, you have this animal called the star-nosed mole, which has this nose with 22 fingers on it, and it feels its way through these tunnels with, like, these 22 fingers, this weird thing. Lots of birds and animals and ins- uh, birds and cows and insects have, um, magnetoreception, so they can pick up on the magnetic field of the Earth, and they can navigate that way. For years, I've stared at this stuff and figuring out, "How in the world does evolution happen so quickly that you can do all this?" And this is what led me to this theory that-... Mother Nature really only had to invent the brain once, figure out the principles of brain operation, and after that, she could spend all of her time tweaking the genetics to make all these weird peripheral devices that you plug in, and it's all plug and play. Whatever weird thing you come up with, you just say, "Okay, cool, I'm gonna plug this in, and I, and I'm sure the brain will figure this out," and it always does, and that's exactly why we can do sensory substitution, and by the way, sensory enhancement or sensory addition, where you can add completely new senses. One example is, uh, my colleagues at Osnabrück built this, this belt that you wear that's got vibratory motors all around it, and it just has a little digital compass on it, so it can tell where north is. So whenever you're, you know, whichever direction north is on your body, you feel that motor buzzing. So it might be on my left hip if north is that way, but if I turn around, I'll feel that on my right hip, and so on. And people get really good at being able to detect which way north is, just as one example. It's really easy to add new senses, like magneto reception in this case, and people can figure this stuff out.

    15. AH

      So cool. Uh, as, as a fan of the X-Men in particular, [chuckles] I mean, you mentioned Magneto, but that's, uh-

    16. DE

      [chuckles]

    17. AH

      ... but in general, I mean, yeah, different mutations give rise to different abilities-

    18. DE

      Yeah

    19. AH

      ... and that whole series of the X-Men is really about kind of extremes of genetic mutations giving abilities-

    20. DE

      Yeah

    21. AH

      ... and, and there's some social discussion in there, too. But, um, let's talk about dreaming because you mentioned that, um, you know, everything

  21. 1:41:36 – 1:49:55

    Why We Dream, Vision & Neuroplasticity, REM Sleep, Blindness

    1. AH

      that we perceive as out there, uh, beyond our reach, um, is occurring by virtue of electrical and chemical events in our brain. It's all vaulted in, in there. Um, dreams are, are a unique situation where typically people's eyes are closed when they sleep, and, um, they're often paralyzed during REM sleep, um, and yet we have very visual dreams. I know you talked about this in Livewire, but please share with us what you think is the origin of the, the visual component of dreams, and I'm curious if it relates back to the, um, uh, the visual imagery, um, continuum that you mentioned earlier. Do some people just tend to have more visual dreams, and other people don't?

    2. DE

      Let me answer that second part first. We're not sure about that. I ask people all the time who are aphantasic or hyperphantasic about their dreams. It's hard to tell. I don't see something obvious there, which is to say, when there's dreams, you're getting this activity blasted into your visual cortex, so it's like vision. So, so let me back up to answer the question about, uh, m- my, my new theory about why we dream, because this has everything to do with brain plasticity. So h- h- here's where this got started. Um, by about 2013, some of our colleagues at Harvard did this experiment where they put people in the scanner, and they blindfolded them tightly, and they were looking at what was going on in the brain and, um, you know, with, with touch and with sounds, and it turns out that if you're blindfolded, after about an hour, you start seeing a little bit of activity in the visual cortex when you are touched or when you, uh, hear something. Now, this was crazy because we know that if somebody goes blind, you know, hearing and touch will take over that territory, but we thought that was on the scale of years, and, and here, what they were demonstrating is that within 60 to 90 minutes, you start seeing little blips of activity. Why? It's because you've got all this cross-modal wiring. In other words, you've got neurons, let's say, in the auditory cortex that actually reach all the way over to the visual cortex, and same with touch neurons and so on. These are normally silent. They don't normally do anything, but they are ready. They're like silent sentinels that say, "Hey, just in case this territory stops getting used, I'm taking over." Okay, so here's what my student and I realized, is that because we live on a planet that rotates into darkness every night, the visual system is at a unique disadvantage because when it's dark, you can still hear and smell and touch and taste, but you can't see, and obviously, I'm talking about evolutionary time before the invention of lights, which is the last nanosecond of evolutionary history. Um, it was really dark at night, and you can't see, and so, you know, you go into the corner of a cave and curl up and go to sleep, but the key is that the visual system was in danger of getting taken over during this long, extended period of darkness. So what we hypothesized is that dreams are the brain's way of defending the visual cortex against takeover from the other senses.

    3. AH

      Hmm.

    4. DE

      And when you look at the circuitry, it's this very specific circuitry. It starts in the midbrain, goes to an area called the lateral geniculate nucleus, and plugs straight into the primary visual cortex, and that's it. Every 90 minutes, you have this volley of activity that just slams into the primary visual cortex. It doesn't go anywhere else in the brain. And so every 90 minutes, you've got this automated way of making activity happen there, and because we are visual creatures, we see that as a dream. We see a whole story, and because the, the brain is a, you know, a storyteller, we impose plot, meaning, and we have emotion that goes with that. Um, but the key is this is the brain's way of defending territory in the dark. And so what we did then is we examined very carefully 25 species of primates and looked at their brain plasticity, um, and you can measure this with different proxies, like, you know, when they start to walk and when they get to reproduction age and so on. And, um, you know, some creatures, like the gray mouse lemur, which is a type of monkey, um, y- you know, he, uh, they are born, let's just say, pre-programmed. You know, they, they pop out, they're really quick to stop, you know, to, to wean and, uh, and, and reach, uh, juvenile age and reproduce and so on. Whereas you look at Homo sapiens, we're super slow. We've got these extended infancies, and we take a long time to learn how to walk and so on. Okay, because we're very plastic, we end up in the world half-baked. Okay, well, it turns out if you plot how much REM sleep each of these animals get, the more plastic the animal, like Homo sapiens, we've got tons of REM sleep, and by the way, this is mostly in infancy. Infants spend 50% of their time in REM sleep. As you get older, and your brain becomes less plastic, you have a drop-off in REM sleep.... And by the way, when you look across animal species of all types, you find that the animals that are born with extended infancies, and need to figure out how to do stuff in the world, um, they all have much more REM sleep, like eight times more REM sleep, than animals that are born essentially mature-

    5. AH

      Yeah

    6. DE

      ... like, you know, uh, cows, and giraffes, and zebras, and whatever. You know, they show up, they start walking in 40 minutes, and so on. Um, they have much less REM sleep than we do. So anyway, this is our hypothesis about why we dream, and it's the only hypothesis that makes quantitative predictions across species.

    7. AH

      Super interesting. Um, and we know that REM-associated dreams are much more, uh, elabor- uh, emotionally elaborate than deep sleep dreams.

    8. DE

      Yeah, and the important part here, of course, is they're more visually elaborate.

    9. AH

      Mm-hmm.

    10. DE

      Um, you know, they- y- there, there are dreams that people can have in deep sleep. Obviously, the way that this gets studied is, you know, is you rouse the sleeper, and you say, "Hey, what were you just dreaming about? What were you just thinking about?" And so if you do that during REM sleep, where their eyes are moving around, uh, they'll say, "Whoa, I was just, you know, riding across a meadow on a camel, and this was what was going on." If you wake somebody during other stages of sleep, deep sleep, they'll, you know... They sometimes have something like, "Well, I was just considering this feeling I had of whatever," but it's not as visual.

    11. AH

      Mm-hmm.

    12. DE

      It's not as rich. By the way, people who are blind still have dreams, but their dreams are not visual. They have a dream like, "Oh, I was, you know, feeling my way around the living room, but all the furniture was rearranged, and then I felt in the corner, and it was a jaguar, and the jaguar started chasing me, and I was trying to get away from it," and so on. But it's sound, it's touch, it's things like that. Why? Because their occipital lobe at the back of their head is not visual. It's kind of for these other things. So the dreaming circuitry, which is very ancient, is just blasting activity into that area of the occipital lobe, and so they experience whatever that correlates with.

    13. AH

      So cool. Um, I wanna move on to, uh, questions that I have about science and the law, but before I do, I just, um... I was told by a, a very, very talented mus- um, magician, uh, mentalist recently, that there's a guy down in Brazil who does, um, magic tricks for blind people using only the auditory domain.

    14. DE

      [gasps]

    15. AH

      And, um, apparently, if you blindfold yourself, and you spend a bit of time around him, you can start to, uh, hear these magic tricks.

    16. DE

      Yeah.

    17. AH

      And they're not just illusions of, of, like, sound leaping. Uh, and so I said, "Well, give me an example." He said, "Y- you have to just experience this." This is something... We should, we should meet this person.

    18. DE

      We should do this. [chuckles] Yeah.

    19. AH

      We should meet this person. Um, uh, just a complete perceptual bend to try and get one's head around that.

    20. DE

      By the way, counselors who are at these, uh, who, who deal with these, uh, blind students at these blind schools, they're generally encouraged to blindfold themselves for, like, seven days-

    21. AH

      Mm.

    22. DE

      -and they absolutely start having totally different experiences. Their brain starts, you know, changing.

    23. AH

      I still won't do one of those darkness cave retreats. People have tried to persuade me-

    24. DE

      Uh-huh

    25. AH

      ... to do those. I have no interest. Um, I love sunlight.

    26. DE

      [laughs]

    27. AH

      I want to keep my circadian rhythm entrainment intact. I, I, uh, uh, n-

    28. DE

      Mm.

    29. AH

      You know, if that's what people want to do... Also, I heard about someone going to do it, and then they flipped on the lights at the end, they went back into see, and the place was covered with spiders.

    30. DE

      Oh! [laughs]

  22. 1:49:55 – 1:56:10

    Victims, Fear, Memory Drift & Recall, Eyewitness Testimony & Jury Education

    1. AH

      how under stressful circumstances, frame rate of perception is not increased, but memory density is higher.

    2. DE

      Yes.

    3. AH

      Can I therefore take the leap that, let's just, let's just say, um, and these are usually tragic circumstances, if there are two individuals, let's limit it to two, for sake of example, in a high-stress, highly traumatic interaction, but one is more stressed than the other-

    4. DE

      Mm

    5. AH

      ... maybe they're the victim in that case, that their density of memory is higher, and therefore, even though there's a perceptual difference, um, perhaps more accurate than, uh, for the person who was calmer? Or is there a threshold at which stress limits memory, and therefore the person who is calmer has a more accurate memory?

    6. DE

      Great question. Well, it turns out, first of all, what victims often have is what's called weapon focus. So if the other person has a knife or a gun, that's all they remember. They... You know, "Describe the guy's face." "I don't remember the guy's face, 'cause I was staring at the gun." So it turns out that what they pay attention to is sort of the wrong thing for forensics purposes. Um, that's number one, but number two is this much deeper issue that even amygdala memories are not necessarily accurate. So, um, you know, our colleague, Elizabeth Phelps, um, did this experiment right after 9/11 in 2001. Shortly after the event happened, she went and interviewed lots of people in Downtown and Midtown New York about what they saw on September 11th, and she was smart enough to interview them also about what they remembered from September 10th. You know, what they ate for breakfast that day, and so on. Okay, she then found them three months later. She followed up a year later. She ended up doing that 10 years later, as well. What they found is that the traumatic memories of 9/11, even though those are amygdala memories, they drifted just as much as the memories of, you know, what they ate, uh, for lunch on September 10th. Um, and so a, an, an unfortunate, uh, fact for the law is that memories are not accurate. They drift. Every time we check in on memories, we're changing them, and it becomes kind of like the operator game, where one person says something in the next- in the other person's ear, and the next person repeats that, and the next person repeats that. There's a sense in which we're always playing the operator game with ourselves, where, you know, each time we pull up a memory, it's changing, and it gets modified and colored by new information that we have. So that's the bad news for the legal system, and so the legal system has gotten really smart about this over the last 30 years, and tried to make sure that they take care of things that happen, let's say, with eyewitness identification. So one thing is, you know, police suggestibility. So if I, if I'm looking at a lineup, and I say, "Gosh, you know, I think that's the guy," and the police officer says, "Yeah, I think that's the guy, you know, I agree with you on that," then what happens is, when I go to court three months later, I, I say to the judge, "Yeah, I'm 100% confident," even though at the time of the lineup, I wasn't confident at all, but I s- come to think I am. There are many, many ways, uh, that-... things get implemented so that we can try to work around, uh, how lousy our memories are. One thing is separating witnesses right away, because if you and I witness a crime, and then you say, "Oh, my g-" you know, "I, I think the guy had long hair," and I say, "No, no, I think it was, uh, short hair," or whatever, w- we're influencing each other's memory, and the things that we say end up changing what the other believes to be true. One of the classes I teach is, uh, The Brain and the Law, and I do this thing every year. I sorta hate to give this away on a podcast, but here, here's what I do. I'm teaching the class, and a woman busts into the back of the classroom and starts screaming at me, and says, "Are you Dr. Eagleman?" I say, "Yeah." I say, "Excuse me, I'm teaching a class." She says, "I've been sending you emails, and you haven't written back, and blah, blah." I say, "Excuse me, I am teaching a class. I, I'm happy to talk to you afterwards. I'm sorry I don't get to all my emails." And she says, "Well, I'm gonna wait for you." Okay, so then I keep teaching the class, and then after, you know, 20 minutes or so, I say to the class, "Look, I, I'm gonna call security, but I don't know what she looked like. I need you guys to write down what you remember about her." I said, "All I remember is that she had a big mole on her left cheek, and, uh, you know, that's all I was able to really see." And so everyone writes down their stuff. Now, not surprisingly, eyewitness identification is terrible. Everyone comes up with extraordinarily different descriptions of what the woman looked like. One thing they tend to have in common is this mole on left cheek, which I made up. The woman doesn't have that, but it's a demonstration that, um, planting something, even accidentally, in my case, on purpose, will influence your memory of what you think happened. Obviously, it's a, it's an actor that I hire every year, but it demonstrates how, how poorly we remember things.

    7. AH

      How does the legal system deal with rec... Forget eyewitness account, just, uh, of, uh, potential perpetrators, but just, like, recollection in general?

    8. DE

      Yeah, well, this went all the way up to the Supreme Court because some guy, some guy was accused from a, you know, he, he got sent to jail based on the eyewitness testimony, m- testimony of a woman who was up on the second floor, seeing him from there, and it was dark out, and, and he said, "Look, that can't be reliable eyewitness testimony." So this went to the Supreme Court, and they said, "Look, sorry, but we can't guarantee, uh, reliable eyewitness testimony, and if we were to ever try to legislate that, that would ruin most court cases," 'cause most things are predicated on eyewitness testimony. So what the legal system tries to do is just educate jurors about this, about how seriously to take it, because, um, a- and by the way, I should mention, unfortunately, people are very swayed by this, jurors are, meaning, you know, a scientist might get up and say, "Look, there's this information or that," but then some, some eyewitness test- you know, eyewitness comes up on the stand and says, "Look, I don't know about all that science stuff, but I know what I saw," and the jury is swayed by that. Um, so it's not easy to educate jurors on this because people fundamentally, even after education, feel like, "Okay, but I know that my memory is like a video camera." Um, so anyway, but that's, that's one thing the legal system tries to do and tries not to take it as, as gospel.

    9. AH

      Are kids versus adults more prone

  23. 1:56:10 – 1:59:27

    Kids vs Adults, Memory Manipulation; Photos

    1. AH

      to making up stories under these circumstances?

    2. DE

      Exactly right.

    3. AH

      I, I think that I, like most perha- I'm not gonna speak for most people. I assume that kids tell the truth. I mean, kids don't always tell the truth, but that they don't understand all the incentives, systems around-

    4. DE

      Ah

    5. AH

      ... lying that some adults do, and so I think we tend to believe what kids say.

    6. DE

      Oh, but kids are actually more susceptible to memory manipulation. So Elizabeth Loftus at Irvine ran these studies years ago, where, um, she, uh... Well, y- y- here's the, uh, sorry, this is slightly different, but what she's doing in these cases is she says to someone, "Hey, I talked to your parents." She, she actually did talk to the person parent, and she says, "I found out a story from when you were younger about the time you got lost in the mall, and you were, uh, found by this woman in a red hat, who then, you know, found your parents and so on." And it turns out she can make these stories completely up, and people will come to believe these, and when she interviews them a week later, they... That is just part of the fact of their life resume-

    7. AH

      [exhales]

    8. DE

      ... is that they were lost in the mall and found by this woman in the red hat and so on.

    9. AH

      I mean, that has huge implications for therapy to unearth, you know, repressed memories and, um, so-called repressed memories.

    10. DE

      Exactly.

    11. AH

      Maybe we need dogs to just, uh, you know, who are completely unbiased, to, uh, evaluate- [chuckles]

    12. DE

      [chuckles]

    13. AH

      ... um, the, uh, veracity of some of these claims.

    14. DE

      Well, here's what I think. Look, you and I grew up in a slightly different world, where if I count the number of childhood photos that I have, that I see, you know, I've got, like, little landmarks every couple of years. "Oh, that was me at eight years old, standing in front of my house in Albuquerque,"-

    15. AH

      Mm-hmm

    16. DE

      ... "and that was me at 10 years old," and so on. But now, you know, we have an Alexa in our kitchen, and it's constantly cycling through the pictures of my kids, who see that every day. They say, "Oh, that was me a few years ago. That was me last month," and so on. I think kids are now much more tightly tied to their memory in a way that might prove very useful.

    17. AH

      Mm-hmm.

    18. DE

      U- unuseful in the sense that maybe you can't get away from your childhood-

    19. AH

      Mm

    20. DE

      ... but useful in the sense that at least your memory's gonna be slightly more accurate because you're getting, you know, uh, repetition, you're getting spaced repetition on it.

    21. AH

      A previous guest hypothesized, I don't think this was based on real data, hypothesized that, you know, like, if you go to a concert now, everyone's taking photos of the concert-

    22. DE

      Yeah

    23. AH

      ... um, as opposed to just experiencing the concert. They hypothesized that, uh, perhaps, uh, people have more memory of the photo-taking experience and the photo than the actual experience-

    24. DE

      Mm

    25. AH

      ... which is a kind of an interesting divergence, like, of, of, like-

    26. DE

      Yeah

    27. AH

      ... the perceptual window that you're taking in information through.

    28. DE

      Right.

    29. AH

      Um, I'm not telling people not to take photos, but it is, or videos, but it is sort of interesting that you're at a concert that, you know, thousands of people are at, um, and everyone's taping it-

    30. DE

      Mm

  24. 1:59:27 – 2:06:31

    Polarization, In vs Out Groups, Empathy; Fairness

    1. AH

      right now. Uh, I think it was always polarized, but it-

    2. DE

      Yeah

    3. AH

      ... seems increasingly so. Um, is it more polarized? And, uh, you've done some interesting work on, um, the neuroscience around polarization, and-

    4. DE

      Yeah

    5. AH

      ... uh, I think it's just important for us to be aware of the fact that we're all prone to this.

    6. DE

      Yeah.

    7. AH

      And perhaps also, I would hope, to also push back on it.

    8. DE

      Yeah.

    9. AH

      But I also feel like people like to be in the echo chamber, that there might be some, uh, dopamine reward or other neuromodulator reward for kind of verifying what we think to be true.

    10. DE

      I also think this is a social thing. I think you can't even talk about beliefs that we hold without talking about what that means for i- identity and for what team we're on.

    11. AH

      Mm-hmm.

    12. DE

      Okay, so let me back up. I think we're not any more polarized than ever before. Just as an example, look at the 20th century. You've got, you know, if you look really what happened with Nazism in Europe or i- in Germany or, or fascism in Italy or what happened in Cambodia with Pol Pot or in Rwanda or the Chinese and com- the Chinese, uh, and Russian communist revolutions, all these things were extraordinarily polarized moments where people took up arms and killed their neighbors. Um, and that was all pre-social media. So I don't think that has much to do with it, except that I do think maybe we're more aware. Because it used to be that everyone was in their echo chambers, also nothing new there, but, you know, all of your friends and neighbors and whatever all believed in whatever, and so you didn't realize there were other people who believed other things. But I think now we're just more, much more exposed to that. Okay, so polarization, nothing really new about that, but it's very important for us to understand this. So, um, one of the experiments we did in my lab was the following: We put people in the brain scanner, fMRI. They see six hands on the screen. All the hands look pretty much alike, and the computer goes around, doo, doo, doo, doo, doo, and it picks one of the hands, and then you see that hand get stabbed with a syringe needle. What happens is, you have this empathic response, specifically this, uh, network of areas that we summarize as the pain matrix, [mouth clicks] comes online. It's not your hand getting stabbed, nonetheless, you're watching a hand getting stabbed, and you... This is the neural basis of empathy. You're feeling, ah, what would it feel like if that were my hand? Great. Okay, now what we do is we put a one-word label on each hand: Christian, Jewish, Muslim, Scientologist, Hindu, Atheist. Computer goes around, doo, doo, doo, picks a hand. You see that hand get stabbed, and the question is, does your brain care as much if it's a member of one of your out-groups versus your in-group? Turns out the answer, depressingly, is that your brain cares much less. So the size of the empathic response, if it's your in-group, is enhanced from what it was, and if it's any one of your out-groups, it's diminished. By the way, this is not a criticism of religion 'cause we find exactly the same thing with atheists. People who profess themselves as atheists really care when they see the atheist hand get stabbed.

    13. AH

      Really, they're, they're-

    14. DE

      Yeah. It's everything about in-groups and out-groups.

    15. AH

      Okay.

    16. DE

      So it turns out this is such a low-level response. Now, happily, this doesn't necessarily map onto how you act as a person. This is just your first response. You care more about your in-groups. Other labs, like Tania Singer and others, have shown very similar versions of this with even things like sports teams. In fact, one of the experiments we did was, um, we brought fresh people in, and we said, "Hey, I want you to toss a coin. If it's heads, you're a Justinian. If it's tails, you're an Augustinian." So they toss the coin. They find out what they are. We give them a wristband that reminds them that they're a Justinian or Augustinian. Then they go in the scanner, and they see Justinian or Augustinian hands getting stabbed, and it turns out they have a bigger response predicated on their team. Completely arbitrary label, it doesn't mean anything.

    17. AH

      Yeah.

    18. DE

      But this is how we are wired, very much, very strongly for in-groups and out-groups. Obviously, this is a real problem for everything we're witnessing around us. Um-

    19. AH

      Can I ask you-

    20. DE

      Please

    21. AH

      ... a question? Um, I have a, a theory, unsubstantiated by any laboratory data, that, uh, we all naturally feel some degree of empathy for both in-group or, or common group and other group, except for groups that we really despise, okay? I think there are some people who do- provided that the other person is being tortured or killed, they're sort of like, "Oh, well, dislike them anyway." But I think we tend to feel, um, we know how we feel about someone or a group when something good happens for them. To me, it's a-

    22. DE

      Yeah

    23. AH

      ... much stronger indicator. So has the reverse experiment ever been done, where instead of the hand getting stabbed with a syringe-

    24. DE

      Mm

    25. AH

      ... um, the person of same group or outside group is being given something that is of, of value? Um-

    26. DE

      That's interesting. I don't know. I, I don't think anyone's run that experiment, to my knowledge.

    27. AH

      'Cause if I tell you, like, okay, if I, if I were to have access to your, uh, your thoughts, and I could find, like, 100 people that you, uh, like on... and arrange, or that you know, uh, in your mind and arrange them on the continuum of really, really adore this person all the way to, like, actually really, I'm not gonna use the word hate, but, like, really, really dislike this person, and I tell you, you know, um, and give any one of them, uh, stage three pancreatic cancer-

    28. DE

      Mm.

    29. AH

      ... I imagine, as an empathic person, you're gonna be like, "Ah, that sucks." But if I instead flip it and say, "Okay, you know, this person you really, you really like, um, they had something spectacular happen to them," versus somebody that you dislike, something spect- there's a d- there's a, there's a little bit of a-

    30. DE

      Mm

  25. 2:06:31 – 2:19:27

    Polarization, Reward vs Punishment; Propaganda, Language, Complexification

    1. AH

      you know, just recently there was this event that's being debated very, uh, intensely from both sides. Someone was shot, whose fault was it? At what d- were they within their rights to shoot her, et cetera? I mean, it's, it's like, it, it's, it's immediate polarization around-

    2. DE

      Yeah

    3. AH

      ... uh, you know, same collection of videos, two totally different interpretations from-

    4. DE

      Right, because was that woman your protagonist or your antagonist? And just like in the movies, we have a completely different, uh, em- empathic response based on that.

    5. AH

      In the, um, [lip smack] sort of hypothetical example of an experiment where people that are either same group or different group are rewarded, I feel like it gets to an issue that's a little bit more subtle than when people are harmed, um, because it gets to the zero s- this notion of zero sum.

    6. DE

      Mm.

    7. AH

      Like, if somebody else gets something, does that mean anything was taken from you?

    8. DE

      Yeah.

    9. AH

      Not necessarily, right? But there are some people who go through life seeing people get things, and they feel the pain of what they didn't get by virtue of-

    10. DE

      Yeah

    11. AH

      ... someone else getting something. And, um, it's gotta be a very difficult place to live, and yet I've known people like that. Um-

    12. DE

      Yeah

    13. AH

      ... they, they, you know, there are people who hate rich people.

    14. DE

      Yeah.

    15. AH

      Um, if, and they hate them b- for l- a number of reasons, maybe they were treated poorly, et cetera. Um, they hate famous people, they hate beautiful people, they hate... Y- you can see this.

    16. DE

      Yeah.

    17. AH

      Right? And what aspect of, of self, other, in-group, out-group does that relate to? 'Cause it gets us to this notion of how much resource there is to go around.

    18. DE

      Yeah.

    19. AH

      Something for someone else is something taken from us is a very different perspective.

    20. DE

      Yeah, that's right. I don't know the answer to that, except that people clearly are wired differently on that in terms of whether they think it's a zero-sum game or there's, you know, infinite resources.

    21. AH

      Do we see it in animals?

    22. DE

      Yes, actually.

    23. AH

      Mm-hmm.

    24. DE

      There are experiments on, on capuchin monkeys where, um, the monkey does something and then gets a, a piece of banana, and then, uh, the other monkey does something in the neighboring cage and gets a piece of banana. And so they're, they're doing this, but then the other monkey doing it gets a grape, which is a big treat for the monkey, and the first monkey goes nuts! And he's shaking the bar. He's so angry that the other monkey got a better reward. Um, we [chuckles] really... There's this sense of fairness that's actually quite deep in our evolution about what's unfair, and so on. But I wanna come back to this issue about rewarding people versus punishing. To my mind, the reason I care so much about this issue of harm happening to people, and when we don't care-

    25. AH

      Mm-hmm

    26. DE

      ... is because of when we look at what happens around the world, I'm not even talking right now, let's just take the 20th century. Um, we constantly see people murdering their neighbors for all kinds of reasons, for religious reasons, for atheist, communist, you know, uh, secular reasons. For all kinds of reasons, people are perfectly willing to take their friends and neighbors... Look at the Hutu and Tutsi in Rwanda. They had lived together, they were friends, there was intermarriage, and then the Hutu, you know, uh, b- you know, raised up their machetes and slaughtered Tutsi at a rate faster than the Germans were able to do with gas chambers and Jews. Um, how these things happen, it's so important for us to understand, what are the elements that lead to in-group and out-group stuff? One of the things I've been very interested in is propaganda, and it turns out across place and time, all governments do propaganda in exactly the same way, which is you simply dehumanize the other group by calling them an animal or, or any, like a virus, a, um, you know, a pestilence, uh, rats. Nowadays, you can even call them robots, whatever. Anything that's not human, that turns off these networks that we have in the prefrontal lobe that care about other humans and how to interact with other humans. Our colleague, Lasona Harris, has studied this stuff. And what happens is, when you're dealing with an object now, like, oh, the Tutsi... The, the famous thing that happened in Rwanda is the Tutsi were described as cockroaches, and the radio was blaring that all the time, "The Tutsi are cockroaches." So, you know, killing a cockroach isn't so hard to do. So you grab your machete, and you go do that, and that's the kind of thing I am, uh, essentially dedicating my life to this kind of thing, is an education about this, such that when the next generation hears propaganda about any group, they say, "Wait a minute, I've heard that trick before. I know what this is. This is just calling the other group, 'Oh, they're not like us. They're not human,'" and so on. Dialing down these networks that care about other humans, therefore, I don't care about them as much, I don't have empathy for them as much, and I'm willing to take up arms against them.

    27. AH

      Many years ago, um, I was at a meeting, and one of our colleagues, I'll let them re- remain anonymous for soon to be obvious reasons, um, made... stood up and made a really strong case for not referring to, um, the mice, and at that time, experiments were still done on, on cats and, um, and non-human primates.... I mean, th- those are still used, but to a lesser extent now, but still, um, to not refer to them as animal models, um, because he felt that it was de- uh, not dehumanizing them, it was, it was, um, removing the sense that they were real beings. And, um, you know, uh, as someone who has worked on a number of species, including humans, um, and, and frankly, I'm-- I'll say this proudly, I'm relieved to not do experiments on animals anymore. I really did not like that aspect. I, I did like working with humans, we say, not on humans. [chuckles] Um, 'cause they can sign up and, uh, consent, and that sort of thing. I think every, uh, profession has this. You know, they, uh... My friends who are psychologists, you said your dad was a psychiatrist. I always ask people, uh, psychologists and psychiatrist, "Do you refer to your, uh, um, the people that you treat as clients or as patients?" Like, the, the language doesn't always matter so much, but I think when it comes to animal experimentation, when it comes to, um, people and professional relationships, it actually does matter.

    28. DE

      Yeah.

    29. AH

      Because I think, as you pointed out, certain circuits in the brain get turned off or on, depending on how we refer to people.

    30. DE

      Yeah, exactly.

  26. 2:19:27 – 2:21:44

    Current Projects; Acknowledgements

    1. AH

      have you back. [chuckles] Of course, you have your own podcast.

    2. DE

      Good.

    3. AH

      Amazing podcast.

    4. DE

      Thank you.

    5. AH

      Uh, so tell us about, just, um, for folks, we'll put links in the, uh, show note captions, but, um, you're wr- you're writing, what, 10 books now? You got a podcast-

    6. DE

      [chuckles]

    7. AH

      ... you're involved in movie, movie scripts.

    8. DE

      Yeah.

    9. AH

      But, uh, give us the highlights. Uh, w- what are you up to these days when you're not teaching three different classes at Stanford?

    10. DE

      So I'm running the podcast, Inner Cosmos, which is-

    11. AH

      Awesome podcast. I listen to it.

    12. DE

      Thank you. Thanks. And that's, that's a really wonderful way for me to put out lots of ideas. Often I do, you know, mostly it's monologue, um, but I do have guests as well. Um, a- and I get to just tackle big philosophical questions about time, about polarization, about whatever. Um, I just signed my next two books. One is The Ulysses Contract, and one I mentioned is called Empire of the Invisible. Um, and then, yeah, I'm also doing a lot in the realm of movie production stuff. Um, we're making a documentary film right now with the comedian Craig Ferguson, where we're asking the question: Can AI be funny? So we've built a robot that Craig is gonna go on the road with and do this comedy with, you know, like, in the middle of the country. And the reason we're starting there is because that allows us to ask all these deeper questions about AI, but in a way that draws people into the movie, 'cause you can't just make, like, a doomy, gloomy movie about AI and expect anybody to watch it. But, but this is sort of a really fun, funny movie that allows us to really ask, what's it gonna mean for our lives?

    13. AH

      Awesome. And when you're not doing that, you're fixing doorknobs-

    14. DE

      Yes

    15. AH

      ... and stuff in your, in your home.

    16. DE

      Yes.

    17. AH

      And raising a family.

    18. DE

      Yeah.

    19. AH

      Uh, David, thanks so much for coming here today.

    20. DE

      Great to see you, Andrew.

    21. AH

      Um, as everyone now sees, and many already knew coming into this, you're a world-class educator and-

    22. DE

      Thanks

    23. AH

      ... uh, storyteller, and most importantly, a scientist, um, who ran experiments. I think it really helps to have, you know, and no, no diss on science communicators that haven't run labs and things like that, but I think when one has done experiments, you get a, a real deep sense for how data comes together and what it does and doesn't mean. And, um, you're a virtuoso, so, um, thanks for coming here today and, and sharing just so many pearls of wisdom, and some practical takeaways, uh, that I know myself and other people are really going to, uh, gonna work with.

    24. DE

      Great. Thanks, Andrew.

    25. AH

      Thanks.

    26. DE

      It's a blast being here.

    27. AH

      Awesome. Come back. Thank you for joining me for today's discussion with Dr. David Eagleman. To learn more about his work

  27. 2:21:44 – 2:24:11

    Zero-Cost Support, YouTube, Spotify & Apple Follow, Reviews & Feedback, Sponsors, Protocols Book, Social Media, Neural Network Newsletter

    1. AH

      and to find links to his various books, please see the links in the show note captions. If you're learning from and/or enjoying this podcast, please subscribe to our YouTube channel. That's a terrific zero-cost way to support us. In addition, please follow the podcast by clicking the Follow button on both Spotify and Apple. And on both Spotify and Apple, you can leave us up to a five-star review, and you can now leave us comments at both Spotify and Apple. Please also check out the sponsors mentioned at the beginning and throughout today's episode. That's the best way to support this podcast. If you have questions for me or comments about the podcast, or guests or topics that you'd like me to consider for the Huberman Lab Podcast, please put those in the comments section on YouTube. I do read all the comments. For those of you that haven't heard, I have a new book coming out. It's my very first book. It's entitled Protocols: An Operating Manual for the Human Body. This is a book that I've been working on for more than five years, and that's based on more than 30 years of research and experience. And it covers protocols for everything from sleep, to exercise, to stress control, protocols related to focus and motivation, and of course, I provide the scientific substantiation for the protocols that are included. The book is now available by presale at protocolsbook.com. There, you can find links to various vendors. You can pick the one that you like best. Again, the book is called Protocols: An Operating Manual for the Human Body. And if you're not already following me on social media, I am hubermanlab on all social media platforms, so that's Instagram, X, Threads, Facebook, and LinkedIn. And on all those platforms, I discuss science and science-related tools, some of which overlaps with the content of the Huberman Lab Podcast, but much of which is distinct from the information on the Huberman Lab Podcast. Again, it's hubermanlab on all social media platforms. And if you haven't already subscribed to our Neural Network Newsletter, the Neural Network Newsletter is a zero-cost monthly newsletter that includes podcast summaries, as well as what we call protocols in the form of one to three-page PDFs that cover everything from how to optimize your sleep, how to optimize dopamine, deliberate cold exposure. We have a foundational fitness protocol that covers cardiovascular training and resistance training. All of that is available completely zero cost. You simply go to hubermanlab.com, go to the Menu tab in the top-right corner, scroll down to Newsletter, and enter your email. And I should emphasize that we do not share your email with anybody. Thank you once again for joining me for today's discussion with Dr. David Eagleman. And last, but certainly not least, thank you for your interest in science. [upbeat music]

Episode duration: 2:24:11

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