The Neuroscience of Speech, Language & Music | Dr. Erich Jarvis

Andrew Huberman 0:00 (peaceful music) 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. Today, my guest is Dr. Erich Jarvis. Dr. Jarvis is a professor at the Rockefeller University in New York City, and his laboratory studies the neurobiology of vocal learning, language, speech disorders, and remarkably, the relationship between language, music, and movement, in particular, dance. His work spans from genomics, so the very genes that make up our genome and the genomes of other species that speak and have language, such as songbirds and parrots, all the way up to neural circuits, that is the connections in the brain and body that govern our ability to learn and generate specific sounds and movements coordinated with those sounds, including hand movements, and all the way up to cognition, that is our ability to think in specific ways based on what we are saying and the way that we comprehend what other people are saying, singing, and doing. As you'll soon see, I was immediately transfixed and absolutely enchanted by Dr. Jarvis's description of his work and the ways that it impacts all the various aspects of our lives. For instance, I learned from Dr. Jarvis that as we read, we are generating very low levels of motor activity in our throat. That is, we are speaking the words that we are reading at a level below the perception of sound or our own perception of those words. But if one were to put an amplifier to measure the firing of those muscles in our vocal cords, we'd find that as we're reading information, we are actually speaking that information. And as I learned and you'll soon learn, there's a direct link between those species in the world that have song and movement, which many of us would associate with dance, and our ability to learn and generate complex language. So, for people with speech disorders, like stutter, or for people who are interested in multiple language learning, bilingual, trilingual, et cetera, and frankly, for anyone who is interested in how we communicate through words, written or spoken, I'm certain today's episode is going to be an especially interesting and important one for you. Dr. Jarvis's work is so pioneering that he has been awarded truly countless awards. I'm not going to take our time to list off all of the various important awards that he's received. But I should point out that in addition to being a decorated professor at the Rockefeller University, he is also an investigator with the Howard Hughes Medical Institute, the so-called HHMI. And for those of you that don't know, HHMI investigators are selected on an extremely competitive basis that they have to re-up, that is they have to re-compete every five years. They actually receive a grade every five years that dictates whether or not they are no longer a Howard Hughes investigator, or whether or not they can advance to another five years of funding for their important research. And indeed, Howard Hughes investigators are selected not just for the rigor of their work, but for their pioneering spirit and their ability to take on high-risk, high-benefit work, which is exactly the kind of work that Dr. Jarvis has been providing for decades now. Again, I think today's episode is one of the more unique and special episodes that we've had on the Huberman Lab Podcast. I single it out because it really spans from the basic to the applied. And Dr. Jarvis's story is an especially unique one in terms of how he arrived at becoming a neurobiologist. So, for those of you that are interested in personal journey and personal story, Dr. Jarvis's is truly a special and important one. I'm pleased

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Andrew Huberman 8:01 Erich Jarvis. Eric, so great to have you here.

Erich Jarvis 8:04 Thank you.

Andrew Huberman 8:04 Yeah. Very interested in learning from you about speech and language, and even as I ask the question, I realize that a lot of people, including myself, probably don't fully appreciate the distinction between speech and language, right? Speech I think of as the motor patterns, the-

Erich Jarvis 8:21 Mm-hmm.

Andrew Huberman 8:22 ... the production of sound, uh, that has meaning hopefully, and language of course come in various languages and varieties of, of ways of communicating. But in terms of the study of speech and language and thinking about how the brain organizes speech and language, uh, what are the similarities? What are the differences? How should we think about speech and language?

Erich Jarvis 8:43 Yeah, um, well, I'm glad you, you know, invited me here, and I'm also glad to get that first question, which I consider a provocative one. Re- the reason why, uh, I've been struggling what is the difference with speech and language for many years, and realize why am I struggling is because there are behavioral terms, let's call them psychologically, psychology-developed kind of terms, um, that don't actually align exactly with brain function, right? And the question is there a distinction between speech and language? And when I look at the brain of work that other people have done, work we have done, also comparative with animal models like those who can imitate sounds like parrots and songbirds, I start to see there really isn't such a sharp distinction. So, so to get at what I think is going on, let me tell you wha- how some people think of it now, that there's a separate language module in the brain, uh, that has all the algorithms and computations that influence the speech pathway on how to produce sound and the auditory pathway on how to perceive and interpret it, uh, for speech or for, you know, s- sound that we call speech. And, um, it turns out I don't think there is any good evidence for a separate language module. Instead, there is a speech production pathway that's controlling our larynx, controlling our jaw muscles, that has built within it all the complex algorithms for spoken language, and there's the auditory pathway that has built within it all the complex algorithms for understanding speech, not separate from a language module. And the speech production pathway is specialized to humans and parrots and songbirds, whereas this auditory perception pathway is more ubiquitous amongst the animal kingdom, and this is why dogs can understand sit, siente-se, come here, ball, boy, get the ball, and so forth. Dogs can understand several hundred human speech words. Great apes, you can teach them for several thousand, but they can't say a word.

Andrew Huberman 10:53 Fascinating.

Andrew Huberman 10:55 Because you've raised, uh, a number of animal species early on here-

Erich Jarvis 10:59 Yeah. (laughs)

Andrew Huberman 10:59 ... and because I have a, basically an obsession with animals since the time I was very small, I have to ask, um, which animals have language? Which animals have modes of communication that are sort of like language?

Erich Jarvis 11:14 Yeah.

Andrew Huberman 11:14 Um, you know, I've heard whale songs. I don't know what they're saying.

Erich Jarvis 11:17 Mm-hmm.

Andrew Huberman 11:17 They sound very beautiful, but I, they could be insulting each other for all I know.

Erich Jarvis 11:21 Yeah.

Andrew Huberman 11:21 Um, and they very well may be. Dolphins, birds, I mean, they... What do we understand about modes of communication that are like language but might not be what would classically be called language?

Erich Jarvis 11:36 Yes, right. So, so modes of communication that people would define as language, more s- very, in a very narrow definition, they would say production of sound, so speech. Um, but what about the hands, the gesturing with the hands? What about a bird who is doing aerial displays in the air communicating information through body language, right? Well, um, I'm going to go back to the brain.So, what I think is going on is for spoken language we're using the speech pathway and all the complex algorithms there. Next to the brain regions that are controlling spoken language are the brain regions for gesturing with the hands, and that hand parallel pathway has also complex algorithms that we can utilize. And some species are more advanced in these circuits whether it's sound or gesturing with hands, and some are less advanced. Now, we humans and a few others are the most advanced for the speech sounds or the s- or the spoken language, but a non-human primate can produce gesturing in a more advanced form than they could produce sound. I'm not sure I got that across clearly.

Andrew Huberman 12:51 No.

Erich Jarvis 12:51 Just to say that humans are the most advanced at spoken language, but not necessarily as big a difference at gestural language compared to some other species.

Andrew Huberman 13:03 Very clear and very interesting and, and immediately prompts the question, uh, have there been brain imaging or other sorts of, uh, studies evaluating neural activity in the context of, you know, cultures and languages at least that I associate with a lot of hand movement like Italian-

Erich Jarvis 13:21 Yep.

Andrew Huberman 13:21 ... versus, uh, I don't know, maybe you could give us some examples of cultures where language is not, uh, associated with, with as much overt hand movement.

Erich Jarvis 13:29 Yes. So as you and I are talking here today and people who are listening but can't see us, we're actually gesturing with our hands as we talk, uh, without knowing it. We're doing it unconsciously. And if we were talking on the telephone, I would have one hand here and I'd be gesturing with the other hand-

Andrew Huberman 13:47 (laughs)

Erich Jarvis 13:48 ... without even you seeing me, right? And so why is that? Uh, some have argued, and I would agree wi- based upon what we've seen, is that there's an evolutionary relationship between the brain pathways that control speech production and gesturing. Uh, and, and the brain regions I mentioned are directly adjacent to each other. And why is that? I think that the brain pathways that control speech evolved out of the brain pathways that control body movement, all right? And, um... (clears throat) That, uh, when you talk about Italian, French, English and so forth, um, each one of those languages come with a learned set of gestures that, uh, you can communicate with. Now how is that related to other animals? Well, Koko, a gorilla who was raised with humans for 39 years, or more, uh, learned how to do gesture communication, learned how to sign language, so to speak, right? But Koko couldn't produce those sounds. Koko could understand them as well by si- by seeing somebody sign or hearing somebody produce speech, but Koko couldn't produce it with her voice. And so what's going on there is that a number of species, not all of them, a number of species have motor pathways in the brain where you can do learned gesturing, rudimentary language if you wanted, say, with your limbs even if it's not as advanced as humans. But they don't have this extra brain pathway for the sound so they can't gesture with their voice in the way that they gesture with their hands.

Andrew Huberman 15:23 I see. One

Andrew Huberman 15:25 thing that I've wondered about for a very long time is whether or not, um, primitive emotions and primitive sounds are the early substrate of language and whether or not there's a bridge that we can draw between those in terms of just the basic respiration systems associated with different extreme feelings. Here, here's the way I'm imagining this might work.

Erich Jarvis 15:50 Mm-hmm.

Andrew Huberman 15:50 When I smell something delicious, I typically inhale more.

Erich Jarvis 15:56 Mm-hmm.

Andrew Huberman 15:57 And I might say, "Mm," or something like that. Whereas if I smell something putrid, I typically turn away, I wince, and I will exhale, (exhales) you know? Or sort of kind of like turn away, try not ingest those molecules or inhale those molecules. I could imagine that these are the basic dark and light contrasts of the, of the language system, and as I say that I'm saying that from the orientation of a vision scientist who thinks of all visual images built up in a b- very basic way of a hierarchical mo- model of the ability to see dark and light. So I could imagine this kind of primitive to more sophisticated, um, uh, pyramid of, of sound to language. Is this a crazy idea? Do we have any, uh, do we have any evidence this is the way it works?

Erich Jarvis 16:45 Uh, no, it's not a crazy idea, and in fact you hit upon one of the key distinctions in the field of research that I started out in which is vocal learning research. So for vocal communication, uh, you have most vertebrate species vocalize but most of them are producing innate sounds that they're born with, uh, producing. Uh, that is babies crying, for example, or dogs barking. Uh, and only a few species have learned vocal communication, the ability to imitate sounds, and that is what makes spoken language special. When people think of what's special about language, it's the learned vocalizations. It's the wha- that is what's rare. And so this distinction between innateness and learned, um, is more of a bigger dichotomy when it comes to vocalizations than for other behaviors in the animal kingdom, and, uh, when you go in the brain you see it there as well. Uh, and so all the things you talked about, the breathing, the grunting, and so forth, a lot of that is handled by the brain stem circuits, you know, right around the level of your neck and below. Uh, like a reflex kind of thing so... Or, or even some emotional aspects of your behavior in the hypothalamus and so forth. But for learned behavior, learning how to speak-... uh, learning how to play the piano, teaching a dog to learn how to do tricks is using the forebrain circuits. And what has happened is that there's a lot of forebrain circuits that are controlling learning how to move body parts in these species, but not for the vocalizations. But in humans and in parrots and some other species, somehow we acquired circuits where the forebrain has taken over the brainstem and now using that brainstem not only to produce the innate behaviors or vocal behaviors, but the learned ones as well.

Andrew Huberman 18:43 Do we have any sense of when modern or sophisticated language evolved? You know, uh, thinking back to the species that we evolved from and even within Homo sapiens-

Erich Jarvis 18:56 Mm-hmm.

Andrew Huberman 18:57 ... um, have, has there been an evolution of language? Has there been a, a devolution of language? (laughs)

Erich Jarvis 19:03 Yeah. Yeah, yeah, I, I would say, um, in, in to be able to answer that question, it does come with a caveat that I think we humans overrate ourselves when it, compared to other species. And so it makes, uh, even scientists, uh, go astray in, in trying to hypothesize when you especially don't find fossil evidence of language that easily. Uh, uh, in, out there, uh, in terms of what happened in the past, um, we pri- pri- amongst the primates, which we humans belong to, we are the only ones that have this advanced vocal learning ability. Uh, now when you g- it was assumed that it was only Homo sapiens. Uh, then you can go back in time now based upon genomic data not only of us living humans but of the fossils that have been found for Homo sapiens, of Neanderthals, of Denisovan, uh, individuals and discover that our ancestor, our human ancestors supposedly hybridized with these other hominid species. And it was assumed that these other hominid species don't learn how to imitate sounds. I don't know of any species today that's a vocal learner that can have children with a non-vocal learning species. I, I don't see it. Doesn't mean it didn't exist. Uh, and when we look at the genetic data from these ancestral hominids that, uh, you know, when we can look at genes that are involved in learned vocal communication, they have the same sequence as we humans do for genes that function in speech circuits. So I think Neanderthals had spoken language. I'm not going to say it's as advanced as what it is in humans. I don't know. Um, but I think it's been there for at least between 500,000 to a million years, uh, that, uh, our ancestors had this ability and that we've been coming more and more advanced with it culturally and pro- possibly genetically. Um, but I think it's evolved sometime in the last 500,000 to a million years.

Andrew Huberman 21:08 Incredible.

Erich Jarvis 21:09 Yeah.

Andrew Huberman 21:10 Maybe we could talk a little bit more about the overlap between brain circuits that control language and speech in humans-

Erich Jarvis 21:17 Yeah.

Andrew Huberman 21:17 ... and other animals. Uh, you know, I was weaned in the, in the neuroscience era where bird song and the, uh, the ability of birds to learn their tutor's song was a, was and still is a prominent field-

Erich Jarvis 21:32 Mm-hmm.

Andrew Huberman 21:32 ... sub-field of neuroscience and then of course neuroimaging of, uh, humans, of speaking and learning, et cetera, and this notion of a critical period, a time in which language is learned more easily than it is later in life. And the names of the different brain areas were quite different. Um, if one opens the textbooks we hear Wernicke's and Broca's for the humans and you look at the bird stuff I remember, you know-

Erich Jarvis 21:57 HPC.

Andrew Huberman 21:58 ... yeah, robust art striatum, area X, right-

Erich Jarvis 22:00 That's right. That's right. Yes.

Andrew Huberman 22:01 ... uh, et cetera. But, um, for most of our listeners that those names won't mean a whole lot. But, um, but in terms of homologies between areas in terms of function, what do we know and, um, how similar or different are the brains, uh, brain areas controlling of speech and language in say a songbird and a, and a young chil- human child?

Erich Jarvis 22:22 Yeah. So, so going back to the 1950s or even a little earlier when Peter Muller and others who got involved in neuroethology, the study of neurobiology of behavior in a natural way, right? Um, you know, they start to find that behaviorally there are these species of birds like songbirds and parrots and now we also know hummingbirds, just three of them out of the 40-something bird groups out there on the planet, orders, that they can imitate sounds like we do. And so that was a similarity. In other words, they had this kind of behavior that's more similar to us than chimpanzees have with us or that chickens have with them, right? They're closer relatives. And then they discovered even more similarities, these critical periods, that if you remove a child, uh, you know, this unfortunately happens where a child is feral and does, is not raised with human and goes through their puberty phase of growth, becomes hard for them to learn a, a language as an adult. So there's this critical period where you learn best, and even later on when you're in, in regular society it's hard to learn. Well, the sa- birds undergo the same thing. And then it was discovered that if they become deaf, we humans become deaf, our speech starts to deteriorate without any kind of therapy. Uh, if a non-human primate or, um, you know, or let's say a chicken becomes deaf, uh, their vocalizations don't deteriorate, very little at least. Uh, well this happens in the vocal learning birds. So there are all these behavioral parallels that came along in a package and then people looked into the brain. Fernando Nottebohm, my former PhD advisor, and began to discover the area X you talked about. Uh, the robust nucleus of the archipallium and, um, and these brain pathways were not found in the species who couldn't imitate, so there was a parallel here.... and then, uh, jumping many years later, you know, I started to dig down into these, uh, brain circuits to discover that these brain circuits have parallel functions with the brain circuits for humans even though they're by a different name like Broca's and laryngeal motor cortex. And most recently, we discovered not only the actual circuitry and the connectivity are similar, but the underlying genes that are expressed in these brain regions in a specialized way different from the rest of the brain are also similar between humans and songbirds and parrots. So all the way down to the genes, and now we're finding the specific mutations are also similar, not always identical, but similar, uh, which indicates remarkable convergence for so-called complex behavior in species separated by 300 million years from a common ancestor. And not only that, we are discovering that mutations in these genes that cause speech deficits in humans like in FOXP2, uh, if you put those same mutations or similar type of deficits in these vocal learning birds, you get similar deficits. So convergence of the behavior is associated with similar genetic disorders of the behavior.

Andrew Huberman 25:25 Incredible. I have to ask, do hummingbirds sing or do they hum?

Erich Jarvis 25:31 Hummingbirds hum with their wings and sing with their syrinx.

Andrew Huberman 25:34 In a coordinated way?

Erich Jarvis 25:36 In a coordinated way. There's some species of hummingbirds, um, that actually will, um, Doug Ashworth showed this, that will flap, uh, their wings and (claps) create a slapping sound with their wings that's in unison with their song and on- and you would not know it, but it sounds like a particular syllable in their songs, uh, even though it's their wings and their voice at the same time.

Andrew Huberman 26:02 Hummingbirds are clapping to their song.

Erich Jarvis 26:04 Clapping, but they're, they're snapping their wings together, uh, in unison with the song to, to make it like if I'm going ba-da-da-da-da ba-da (claps) you know, and I banged on the table, except they make it almost sound like their voice with their wings.

Andrew Huberman 26:20 Incredible.

Erich Jarvis 26:20 Yes.

Andrew Huberman 26:21 I, I'm-

Erich Jarvis 26:22 And they got some of the smallest brains around.

Andrew Huberman 26:23 I guess as a kid you would say, "Mind blown," right?

Erich Jarvis 26:25 Yes, yes.

Andrew Huberman 26:26 Incredible.

Erich Jarvis 26:26 Yes.

Andrew Huberman 26:27 Incredible. I love hummingbirds and I always feel like it's such a, a special thing to get a moment to see one because they move around so fast and they flit away-

Erich Jarvis 26:34 Mm-hmm.

Andrew Huberman 26:34 ... so fast in these ballistic trajectories.

Erich Jarvis 26:36 Yep.

Andrew Huberman 26:37 That when you get to see one stationary for a moment or even just hovering there, it's, you feel like you're extracting so much from their little, little microcosm of life, but now I realize they're, they're playing music essentially.

Erich Jarvis 26:49 Right, exactly. And what's amazing about hummingbirds, and I, we're gonna say vocal learning species in general, is that for whatever reason, they seem to evolve multiple complex traits. You know, this idea that evolving language, spoken language in particular, comes along with a set of specializations.

Andrew Huberman 27:09 Incredible.

Erich Jarvis 27:10 Yeah.

Andrew Huberman 27:11 When I was coming up in neuroscience, I learned that, I think it was the work of Peter Marler, that, um, young birds learn, songbirds learn their tutor's song and learn it quite, quite well, but that they could learn the song of another tutor. In other words, they could learn a different, and for the listeners I'm doing air quotes here, a different language, a different bird song.

Erich Jarvis 27:35 (laughs) Mm-hmm.

Andrew Huberman 27:35 Different than their own species' song.

Erich Jarvis 27:37 Yeah.

Andrew Huberman 27:37 But never as well as they could learn their own natural, genetically linked song.

Erich Jarvis 27:44 Yes.

Andrew Huberman 27:44 Genetically linked meaning that, uh, it would be like me being raised in a different culture and, um, that I would learn the, the other language, but not as well as I would have learned English. This, this is the idea.

Erich Jarvis 27:56 Yes.

Andrew Huberman 27:57 Is that true?

Erich Jarvis 27:57 That is true, yes. And that's, and that's what I learned growing up as well and, and, and talked to Peter Marler himself about before he passed. Um, he had this, he used to call it the innate predisposition to learn, all right? So, um, which would be kind of the equivalent in the linguistic community of universal grammar. There is something genetically influencing our vocal communication on top of what we learn culturally, and so there's this be- balance between the genetic control of speech, or a song in these birds, and the learned, uh, cultural control. And so, so yes, if you were to take, um, you know, um, I mean in this case we, we actually tried this at Rockefeller later on, take a zebra finch and raise it with a canary, it would sing a song that was sort of like a hybrid in between. We call it a caninch, right?

Andrew Huberman 28:51 (laughs)

Erich Jarvis 28:52 (laughs) Uh, and vice versa for the canary because there's something different about their vocal musculature, the gen- or the circuitry in the brain. And with a zebra finch, even with a closely related species, if you would take a zebra finch, a young animal, and in one cage next to it place its own species, adult male, right? And in the other cage place a Bengalese finch next to it, it would preferably learn the song from the, its own species' neighbor. But if you remove its neighbor, it would learn that Bengalese finch very well.

Andrew Huberman 29:24 Fantastic.

Erich Jarvis 29:25 So there's, it, it has something to do with also the social bonding with your own species.

Andrew Huberman 29:30 Incredible. That raises a question that I, based on something I also heard but don't have any, uh, scientific peer-reviewed publication to point to, which is this, this idea of pidgin, not the bird, but this idea of when multiple cultures and languages converge in a given geographic area, that the children of all the different native languages will come up with their own language. I think this was in island culture, maybe in Hawaii-

Erich Jarvis 29:55 Mm-hmm.

Andrew Huberman 29:55 ... called pidgin-

Erich Jarvis 29:56 Mm-hmm.

Andrew Huberman 29:56 ... which is sort of a hybrid of the various languages that their parents speak at home and that they themselves speak, and that somehow pidgin, again not the bird but a language called pidgin for reasons I don't know, harbors certain basic elements of all language.

Erich Jarvis 30:14 Mm-hmm.

Andrew Huberman 30:14 Is that true?... is that not true?

Erich Jarvis 30:16 I, I, I would s- I haven't studied enough myself in, in terms of pidgin specifically but in terms of cultural evolution of language and hybridization between different cultures and so forth, uh, even amongst birds with different dialects, uh, and you bring them together, uh, you know, what is going on here is cultural evolution remarkably tracks genetic evolution. So if you bring people from two separate populations together that have been in their separate populations evolutionarily at least for hundreds of generations, so someone speaking Chinese, someone speaking English, uh, and that child, uh, then is learning from both of them, yes, that child's going to be able to pick up and merge, uh, uh, uh, phonemes and words together in a way that an adult wouldn't. Because why? They're experiencing both languages at the same time during their critical period, uh, years, in a way that, um, adults would not be able to experience and so you get a hybrid. And the lowest common denominator is going to be what they share, and so the phonemes that they've re- retained in each of their, uh, uh, languages is what's going to be, I imagine, used the most.

Andrew Huberman 31:33 Interesting.

Andrew Huberman 31:35 So we've got brain circuits in songbirds and in humans that in many ways are similar, perhaps not in their exact wiring-

Erich Jarvis 31:43 Mm-hmm.

Andrew Huberman 31:43 ... but in their basic contour of wiring, and genes that are expressed in both sets of neural circuits in very distinct species that are responsible for these, these phenomenon we're calling speech and language. What sorts of things are those genes controlling? What's... I, I could imagine they were controlling, uh, the wiring of connections between brain areas.

Erich Jarvis 32:05 Yeah. Mm-hmm.

Andrew Huberman 32:05 You know, essentially a map of, you know, of a circuit, basically like an engineer would des- sign a circuit for speech and language, nature designed the ser- circ-

Erich Jarvis 32:13 Mm-hmm.

Andrew Huberman 32:13 ... for speech and language. But presumably other things too like the ability to, um, connect mo- motor patterns within the throat, of muscles within the throat, and the control of the tongue. I mean, what are, what are these genes doing?

Erich Jarvis 32:27 You're pretty good. Yeah, you've made some very good guesses there that, uh, make sense. Uh, so... (clears throat) So yes, uh, one of the things that differ in the speech pathways of us and these song pathways of birds is some of the connections are fundamentally different than the surrounding circuits. Like a, um, a direct cortical connection, uh, from the areas that control vocalizations in the cortex to the motor neurons that control the larynx in, uh, humans or the syrinx in birds. And so we actually made a prediction, uh, that since some of these connections differ, we're gonna find genes that d- that control neural connectivity, uh, and that specialize and that function that differ, and that's exactly what we found. Uh, um, genes that control what we call axon guidance and and connections, and what was interesting, it was sort of in the opposite direction than we expected. That is, some of these genes, actually a number of them that control neural connectivity were turned off in the speech circuit. All right? Uh, and it didn't make sense to us at first, and so we started to realize the function of these genes are to repel connections from forming, so repulsive molecules. And so when you turn them off, they allow certain connections to form that normally would have not formed. So it's a... So by turning it off, you got a gain-of-function for speech. All right? Um, uh, other genes that surprised us were genes involved in calcium buffering, neuroprotection, like parvalbumin or heat shock protein, so when your brain gets hot, these proteins turn on. And we couldn't figure out for a long time why is that the case. And then the idea popped to me one day and said, "Ah," when I heard the larynx is the fastest-firing muscles in the body. All right? In order to vibrate sound and, and modulate sound in the way we do, you have to control... You have to move those muscles, you know, three to four to five times faster than just regular walking or running. And so, um, when you stick electrodes in, in the brain areas that control learned vocalizations in these birds and I think in humans as well, uh, those neurons are firing at a higher rate to control these muscles. And so what is that going to do? You're going to have lots of toxicity in those neurons unless you upregulate molecules that take out, uh, the extra load that is needed to control the larynx. And then finally, a third set of genes that are specialized in the speech circuit are involved in neuroplasticity. Uh, neuroplasticity meaning allowing la- the brain circuits to be more flexible, uh, so you can learn better. And why is that? I think learning how to produce speech is a more complex learning ability than, say, learning how to walk or, or learning how to do tricks and jumps and so forth that dogs do.

Andrew Huberman 35:19 Yeah. It's interesting as you say that because I, I realize that many aspects of speech are sort of reflexive. I'm not thinking about each word I'm going to say-

Erich Jarvis 35:27 Mm-hmm.

Andrew Huberman 35:27 ... I ju- they just sort of roll out of my mouth hopefully (laughs) with some forethought.

Erich Jarvis 35:31 (laughs)

Andrew Huberman 35:31 We both know people that, uh, th- seem to speak, uh, think less, fewer synapses between their brain and their mouth than others, right?

Erich Jarvis 35:38 Yes.

Andrew Huberman 35:38 A lot of examples out there. And some people are very deliberate in their speech. But nonetheless that, um, much of speech is, uh, has to be precise-

Erich Jarvis 35:46 Mm-hmm.

Andrew Huberman 35:46 ... and some of it less precise.

Andrew Huberman 35:49 In terms of plasticity of speech and the ability to learn multiple languages, but even just one language, what's going on in the critical period, the so-called critical period?

Erich Jarvis 35:59 Yeah.

Andrew Huberman 35:59 Why is it that... Um, so my niece speaks Spanish, she's Guatemalan, speaks Spanish and English incredibly well. She's 14 years old.

Erich Jarvis 36:07 Mm-hmm.

Andrew Huberman 36:08 I've struggled with Spanish my whole life. My father's bilingual, my mother is not. I've tried to learn Spanish as, as an adult. It's really challenging. I'm told that had I learned it when I was eight, I would be better off.

Erich Jarvis 36:19 That's right.

Andrew Huberman 36:19 Um, or it would be installed within me. So the first question is-Is it easier to learn multiple languages without an accent early in life and if so, why? And then the second question is, if one can already speak more than one language as a consequence of childhood learning, is it easier to acquire new languages later on?

Erich Jarvis 36:40 So, so the answer to both of those questions is yes, in that, um, but I, but I, but to, to explain this, I need to let you know, actually the entire brain, uh, is undergoing a critical period development, not just the speech pathways. And, uh, so it's easier to learn how to play a piano, it's easier to learn how to ride a bike for the first time and so forth as a young child than it is, uh, later in life. What I mean easier in terms of when you start from, you, you start from first principles of learning something. So the very first time that you're going to learn Chinese as a child versus the very first time you learn Chinese as an adult or learning to play pi- piano as a child versus an adult. Uh, but the speech pathways, or let's say speech behavior, I think has a stronger critical period, uh, change to it than other circuits. Uh, and why, what's going on there in general? Uh, if you c- uh, why do you need a critical period to make you more stable? Uh, to make you more stubborn, so to speak? Uh, the reason I believe is that the brain is not f- The brain can only hold so much information, and, uh, if you are undergoing rapid learning to learn, to acquire new knowledge, you also have to, you know, dump stuff. Put, put memory or information in, in the trash like in a computer. Y- you only have so many gigabases of memory, and so therefore, um, plus, plus also for survival, you don't want to keep forgetting things. And so, so the brain is designed, I believe, to undergo this critical period and solidify the circuits with what you learned as a child and you use that for the rest of your life. And we humans stay even more plastic in our brain functions controlled by a gene called SRGAP2, we have an extra copy of it that leaves our speech circuit and other brain regions in a more immature state throughout life compared to other animals. So we're, we're more immature. We're still juvenile like compared to other animals.

Andrew Huberman 38:49 I knew it.

Erich Jarvis 38:50 But we, but we still go through the critical periods like they all do. And now, the question you asked about if you learn more, um, languages as a child, can you, is it easier to learn as an adult? And that's a common, uh, finding out there in the literature. There are some that argue against it, but for those that support it, the idea there is, um, you, you are born with a set of innate sounds you can produce of phonemes and you narrow that down because not all languages use all of them. And so you narrow down the ones you use to string the phonemes together into words that you learn and you maintain those phonemes as an adult. And here comes along another language that's using those phonemes or in, in different combinations you're not used to, uh, and therefore you, it's like starting from first principles. But if you already have them in multiple languages that you're using, then it makes it easier to use them in another third or fourth language.

Andrew Huberman 39:47 I, I see. Incredible.

Erich Jarvis 39:49 So, so it's not like your brain has under, has maintained greater plasticity. It's your ma, your brain has maintained greater ability to produce different sounds that then allows you to learn another language faster.

Andrew Huberman 40:02 Got it. Are the hand gestures associated with sounds or with meanings of words?

Erich Jarvis 40:10 I think the hand gestures are associated with both the sounds and the meaning. Uh, when I say sound, like if you are really angry, right, uh, and you are n- making a loud screaming noise, right, you may make hand gestures that are, look like you're going to beat the wall, right? Because you're making loud sounds and loud gestures. All right? Um, but if you want to explain something like, "Come over here," what I just do now to you, for those who can't see me, I swung my hand towards you and swung it here to me, that has a meaning to it, to come here. So just like with the voice, this, the hand gestures are producing both, uh, uh, you know, bo- both qualities of sounds.

Andrew Huberman 40:53 And for people that speak multiple languages, especially those that learn th- those multiple languages early in development, do they switch their patterns of motor movements according to, let's say, uh, going from Italian to Arabic or from Arabic to French, um, in a way that matches the, the precision of language that they're speaking?

Erich Jarvis 41:14 You know what? You just asked me a question I don't know the answer to. I would imagine that would make sense because of, of, of switching, uh, in terms of sometimes people might call this code switching, even different dialects of the same language. Could you do that with your gestures? I imagine so, but I really don't n- know if that's true or not.

Andrew Huberman 41:34 Well, I certainly don't know from my own experience because I only speak one language. (laughs)

Erich Jarvis 41:39 (laughs)

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Andrew Huberman 42:52 special offer. To-... go a little bit into the abstract, but not too far.

Erich Jarvis 42:56 Mm-hmm.

Andrew Huberman 42:57 Um, what about modes of speech and language that seem to have a depth of emotionality and meaning, but for which it departs from structured language? Here's what I mean, uh, poetry.

Erich Jarvis 43:09 Mm-hmm.

Andrew Huberman 43:09 Uh, I think of musicians, like there's some Bob Dylan songs that, to me, uh, I understand the individual words. I like to think there's an emotion associated with it, at least I experience some sort of emotion and I have a guess about what he was experiencing. But if I were to just read it linearly without the music and without him singing it or somebody singing it like him, it wouldn't hold any meaning. So in other words, uh, words that seem to have meaning but not associated with language, but somehow tap into an emotionality.

Erich Jarvis 43:43 Yeah. Yep, absolutely. So, so we call this difference, um, semantic communication, communication with meaning, and effective communication, communication that has more of an emotional feeling content to it, you know, but not with, you know, the semantics. And the two can be mixed up. Like with singing words that have meaning, but also have this affective emotional... you just love the sound of the singer that you're hearing. And, uh, initially, um, uh, you know, psychologists, scientists in general thought that these were going to be controlled by different brain circuits. Uh, and i- and it is the case, there are emotional brain centers in the hypothalamus, in the cingulate cortex, and so forth that do give tone to the sounds. But, um, I believe, you know, based upon imaging work and work we see in birds when, when birds are communicating semantic information in their sounds, which is not too often but it happens, versus, uh, affective communication, sing because I'm trying to attract a mate, my courtship song, or defend my territory, it's the same brain circuits. It's the same speech-like or song circuits are being used in different ways.

Andrew Huberman 45:00 Uh, a friend of mine who's also a therapist, uh, said to me, "You know, it's possible to say 'I love you' with intense hatred and to say 'I hate you' with intense love."

Erich Jarvis 45:10 Right.

Andrew Huberman 45:10 And, uh, reminding me that it's possible to hear both of those statements, uh, in either way. So, uh, I guess it's not just limited to song or poetry, it also, um, there's something about the intention and the emotional context in which something's spoken that it can heavily shape the way that, uh, we interpret what we hear.

Erich Jarvis 45:31 That's right. And, and, and I consider all of that actually meaning, even though I defined it as, as people commonly do, semantic and effective communication. Effective communication to say, "I hate you," but meant love, right? Is, um, does have emotional meaning to it, you know. And so one's more like an object kind of meaning or an abstract kind of meaning. Th- there's several other points here I think it's important for, for th- those listening out there to hear, is that when I say also this effective and, um, semantic communication, um, being used by similar brain circuits, it also matters the side of the brain. Uh, in birds and in humans, um, there's, there's left/right dominance, uh, for learned, uh, communication, learned sound communication. Uh, so the left in us humans is more dominant for speech, but the right has a more balance for singing or processing musical sounds as opposed to processing speech. Both get used for both reasons. And so when people say, "Your right brain is your artistic brain and your left brain is your thinking brain," this is what they're referring to. Uh, and, uh, so that's another distinction. The second th- uh, thing that's useful to know is that all vocal learning species use their learned sounds for this emotional, affective kind of communication. But only a few of them, like humans and some parrots and dolphins, use it for the semantic kind of communication we're calling speech. And, and that has led a number of people to hypothesize that the evolution of spoken language or speech evolved first for singing, uh, for this more, like, emotional kind of mate attraction, like the Jennifer Lopez, the Ricky Martin kind of songs and so forth. Uh, and then later on, it became used for abstract communication like we're doing now.

Andrew Huberman 47:31 Oh, interesting.

Andrew Huberman 47:32 Well, that's a perfect segue for me to be able to ask you about your background, um, and motor control not only of the hands, but of the body. So you have a, a number of important distinctions to your name, but one of them, um, is that you were a member of the Alvin Ailey Dance, uh, School? School of Dance?

Erich Jarvis 47:52 That's right. That's right. Mm-hmm.

Andrew Huberman 47:53 Um, so you're, you're an accomplished or, and quite able dancer, right? Um, tell us a little bit about your, um, background in the, the world of dance and as, how it informs your interest in neuroscience. (clears throat) Excuse me. And perhaps even how it relates specifically to your work on speech and language.

Erich Jarvis 48:12 Yes. Well, it's, it's interesting and th- this kind of history even goes before my time. So in my family, my mother and father's side, they both went to the High School of Music & Art here in New York City. Uh, and particularly in my mother's family going back multiple generations, they were singers. And I even did my family genealogy and found out not only, you know, we have some relationships to some well-known singers, distant relationships like Thelonious Monk, but going back to the plantations in North Carolina and so forth, m- my ancestors were singers in the church for the, you know, the towns and so forth. And this somehow got passed on multiple generations to my family and I thought I was gonna grow up and be a famous singer, right? And m- me and my brothers and sister formed a band when we were kids and, and so forth and... But it turned out...... that I didn't inherit the singing talents of some of my other family members even though, you know, I was, you know, okay, you know, but not like my brother, not like my mother or my aunts and my cousin who is now a talented Native American singer. And so, um, so, uh, what ha- w- that then influenced me to do other things and I started, uh, you know, competing in dance contests. Uh, you know, actually this is around the time of the Saturday Night Fever and I was n- I was a teenager and I started win- winning dance contests and I thought, "Oh, I can dance." And I auditioned for the High School of Performing Arts and I got in here in New York City, uh, and got into, uh, ballet dance and got in, right, and, and thought if I learn ballet I can learn everything else. It was that idea if you learn something classical, it can teach you f- everything else. Uh, and I was, yeah, at Alvin Ailey Dance School, Joffrey Ballet Dance School, and at the end of my senior, uh, s- uh, concert, uh, I was- had this opportunity to audition for the Alvin Ailey Dance Company and I had an opportunity to go to college, and I also fell in love with another passion that my father had which was science. And so I liked science in high school and I found an overlap also between the arts and sciences, you know, both required creativity, hard work, discipline, you know, n- new discovery, both weren't boring to me, and the one decision I made at that, at that s- senior dance concert was, you know, when talking to the Alvin Ailey recruiter and thinking about it, I have to make a decision. And I thought something my mother taught me 'cause she was grown up in the 1960s cultural revolution, "Do something that has a positive impact on society." And I thought I can do that better as a dancer than a scientist. So now jump, (clears throat) I get into college, undergraduate school, I major in molecular biology and mathematics, I decide I want to be a biologist, got into graduate school, wanted to study the, the brain at, you know, at the Rockefeller University so I went from Hunter College to Rockefeller University and so now I got to the brain and I s- and why did I choose the brain is because it controls dancing. (laughs)

Andrew Huberman 51:17 (laughs)

Erich Jarvis 51:17 But I didn't, there wasn't anybody studying dancing and I wanted to study the brain, something that it does that's really interesting and complex and I thought, "Ah, language is what it does." You couldn't study that in mice, you couldn't study in non-human primates, but these birds do this wonderful thing that Fernando Nottebohm was studying at Rockefeller. And so that's what got me into the birds. Uh, and, um, (clears throat) uh, and then jumping now 15 years later, you know, m- y- yeah, that's right, even after I'm into now having my own lab studying vocal learning in these birds as a model for language in humans, it turns out that, uh, uh, you know, Ani Patel and, uh, you know, others, uh, have discovered, um, that, uh, only vocal learning species can learn how to dance.

Andrew Huberman 52:04 Is that right?

Erich Jarvis 52:05 That's right. Yes.

Andrew Huberman 52:07 Tha- uh, so I've seen these, um, just, uh, scrolling through the, the files here in my, in my mind. I think about every once in a while someone will s- I love ch- uh, parrots.

Erich Jarvis 52:15 Yes.

Andrew Huberman 52:15 Um, every once in a while someone will send me one of these little Instagram or Twitter videos of a parrot doing what looks to me like dance, typically it's a cockatoo.

Erich Jarvis 52:23 That's right.

Andrew Huberman 52:24 Right?

Erich Jarvis 52:24 That's right.

Andrew Huberman 52:24 With even foot stomping to-

Erich Jarvis 52:26 Yep.

Andrew Huberman 52:26 ... the sound and with-

Erich Jarvis 52:27 A famous one called Snowball out there, but there are n- there are many Snowballs out there. Yes. (laughs)

Andrew Huberman 52:31 (laughs) They're all m- all the dancing birds are named Snowball? Um, that's interesting tactic.

Erich Jarvis 52:36 (laughs) .

Andrew Huberman 52:36 Um, so only animals with language dance?

Erich Jarvis 52:40 Yeah, vocal learning in particular, the ability to imitate sounds. Yes.

Andrew Huberman 52:44 Incredible.

Erich Jarvis 52:45 Yes. And this now is bringing my life full circle, all right? And I've, and, and so when that was discovered in 2009, uh,

Erich Jarvis 52:55 at that same time in my lab at Duke we had discovered that vocal learning brain pathways in songbirds as well as in humans and in parrots, right, like Snowball, uh, are embedded within circuits that control learning how to move. And that led us to a theory we call the brain pathway or motor theory of vocal learning origin where the brain pathways for vocal learning and speech evolve by a whole duplication of the surrounding motor circuits involving learning how to move. Now, how does that explain dance, right? Well, when c- when Snowball, the cockatoos, are dancing, they're using the brain regions around their speech-like circuits to l- to do this dancing behavior. And so what's going on there? What we, what we hypothesize and now like to test is that when this, when, when speech evolved in humans and the equivalent behavior in parrots and songbirds, it required a very tight integration in the brain regions that can hear sound with the brain regions that control your muscles from moving your larynx and tongue and so forth for producing sound. And that tight auditory motor integration we argue then contaminated the surrounding brain regions, and that contamination of the surrounding brain regions now allows us humans in particular and parrots to coordinate our muscle movements of the rest of the body with sound in the same way we do for speech sounds.

Andrew Huberman 54:30 Well, m-

Erich Jarvis 54:31 So we're speaking with our bodies when we dance.

Andrew Huberman 54:33 Incredible. And, uh, and I have to say that as poor as i am at speaking multiple languages, I'm even worse at dancing. So, um...

Erich Jarvis 54:41 (laughs) But I guarantee you're better than a, uh, monkey.

Andrew Huberman 54:44 Uh, but not Snowball the cockatoo.

Erich Jarvis 54:45 N- maybe not Snowball.

Andrew Huberman 54:47 (laughs)

Erich Jarvis 54:47 Y- on YouTube we have a video where there's some scientists dancing with Snowball-

Andrew Huberman 54:51 Oh, wow.

Erich Jarvis 54:51 ... and you'll see Snowball's doing better than some of the scientists.

Andrew Huberman 54:54 Okay. Well, as long as I'm not the worst of all scientists at dancing.

Erich Jarvis 54:57 No. Right. (laughs) .

Andrew Huberman 54:57 Um, there's always neuroplasticity, uh, may it save me some day.

Andrew Huberman 55:03 You said something incredible that I've, I, I-... completely believe even though I have, um, minimum to, uh, let's just say minimum dancing ability. Okay. I can get by at a party or wedding without complete embarrassment, but I don't have any structured training. Um...

Erich Jarvis 55:19 Mm-hmm.

Andrew Huberman 55:20 So, the body clearly can communicate with movement. I, as a trained dancer and knowing other trained dancers, I always think of dance and bodily movement and communication through bodily movement as a form of wordlessness, like a state of wordlessness. In fact, the, the few times when I think that maybe I'm actually dancing modestly well for the context that I'm in where I see other people dancing and they seem to be very much in the movement, it's almost like a state of non-language, uh, non-spoken language.

Erich Jarvis 55:55 Mm-hmm.

Andrew Huberman 55:56 Um, and, and yet what you're telling me is that there's a, a direct bridge at some level between the m- the movement of the body and, and language. So is there a language of the body that is distinct from the language of speech? And if so or if not, how do those map onto one another? What does that Venn diagram look like?

Erich Jarvis 56:17 Yeah. Yeah. So, so, so let me define first dance in this context of vocal learning species. This is the kind of dancing that we are specialized in doing and other, and the vocal learning species are specialized in doing, is synchronizing body movements of muscles to the rhythmic beat of music, and for some reason, we like doing that. We like synchronizing to sounds, uh, and doing it together as a group of people. And that kind of communication amongst ourselves is more like the effective kind of communication I mentioned earlier, unlike the semantic kind. So we humans are using our voices more for the semantic abstract communication, but we're using learned dance for the effective emotional bonding kind of communication. It doesn't mean we can't communicate semantic information w- in dance, and we do it. Um, but it's not as popular. You know, like a ballet that, you know, in The Nutcracker, it is popular, you know, where they are communicating, you know, um, the Arabian guy comes out, which I was the Arabian guy in the ballet Nutcracker.

Andrew Huberman 57:28 Oh, yeah.

Erich Jarvis 57:28 That's how I remember it, yeah, for the Westchester Ballet Company when I was a teenager. Uh, you know, we're, we're trying to communicate meaning in our ballet dance and it can go on with a whole story and so forth, and, but people don't interpret that as clearly as speech. You know, they're seeing the ballet with semantic communication with a lot of emotional content. Whereas you go out to a club, you know, yeah, you're, you're not coming, communicating he- okay, how are you feeling today, tell me about your day, and so forth. You're trying to synchronize with other people in an effective way, and I think that's because the b- the dance brain circuit inherited the more ancient part of the speech circuit which was for singing.

Andrew Huberman 58:12 I always had the feeling that with certain forms of music, um, in particular opera, but any kind of, uh, music where there are some long notes, um, sung, that at some level there was a, a literal resonance created between the singer and the listener that, um, or I think of like the deep voice of a, of a Johnny Cash or where at some level you can almost feel the voice in your own body.

Erich Jarvis 58:39 Mm-hmm.

Andrew Huberman 58:40 And in theory, that could be the, the vibration of the, the, or the firing of the phrenic nerve controlling the diaphragm for all I know. Is there any evidence that there's a coordination between performer and audience at the l- at the level of mind and body?

Erich Jarvis 58:58 Um... I'm gonna say possibly yes. Uh, and the reason why is because I just came back from a conference on the neurobiology of dance, uh, um, that in-

Andrew Huberman 59:10 Clearly, I'm going to the wrong meetings. (laughs)

Erich Jarvis 59:11 Yeah. A colleague, uh, you know,

Narrator 59:13 Invited me.

Andrew Huberman 59:13 Vision science can be so boring. (laughs)

Erich Jarvis 59:14 Yes. Well, one of my colleagues, T- Tecumseh Fitch and Jonathan Fritz, they or- organized th- well, a particular section on, on this conference in Virginia, and this is the first time I was in the room with m- so many neuroscientists studying the neurobiology of dance. It's a new field now in the last five years. And, um, there was one, uh, uh, lab where they were putting EG electrodes on, uh, the dancers, on two different dancers partnering with each other, as well as, uh, the audience, you know, uh, seeing the dance, and the, and some, you know, argued, okay, if you're listening to the music as well, how are you responding 'cause you're, you're asking a question about music and I'm giving you an answer about dance. And what they found is that, you know, uh, the dancers when they resonated with each other during the dance or the audience listening to the dancers and the music, there's some resonance going on there that they score as higher resonance. Their brain activity with these wireless EG signals are showing something different. And so, that's why I say possibly yet. It, it needs, it needs more vigorous study, uh, and, you know, this is some stuff they published but it's not prime time yet, uh, but they're trying to figure this out.

Andrew Huberman 1:00:29 I love it. So at least, um, if I can't dance well, maybe I can hear and feel what it is to dance...

Erich Jarvis 1:00:35 Yes.

Andrew Huberman 1:00:35 ... in a certain way.

Erich Jarvis 1:00:36 That, that's right. And, and, and this'll be some people will think that they even songs that they hear, uh, and they can k- almost sing to themselves in their own head and they know what they want it to sound like and they know when it really sounds good, what it sounds like, but they can't get their voice to do it.

Narrator 1:00:55 (laughs)

Andrew Huberman 1:00:55 I'm raising... For those listening, I'm raising my hand.

Erich Jarvis 1:00:58 Right.

Andrew Huberman 1:00:58 Uh, no, no musical ability.

Erich Jarvis 1:01:00 (laughs)

Andrew Huberman 1:01:00 Uh, others in my household have tremendous musical ability with instruments and with voice, but, uh, not me.

Erich Jarvis 1:01:06 Yeah, well, and, and so this is one of my, one of my, um, selfish goals of trying to find the genetics...... of why can some people sing really well and some not? Is there some genetic predisposition to that and then can I modify my own muscles or brain circuits to sing better? (laughs)

Andrew Huberman 1:01:24 You're still after the, the singing. I guess this is what happens when siblings are, um, varying in proficiency is that-

Erich Jarvis 1:01:31 Yes.

Andrew Huberman 1:01:31 ... that competitiveness amongst, uh, brothers and sisters never goes away.

Erich Jarvis 1:01:34 I've been trying to be as good as my brother, Mark and Victor, you know, for, uh, the rest, the who- my entire life. (laughs)

Andrew Huberman 1:01:40 All right. Watch out Mark and Victor-

Erich Jarvis 1:01:41 (laughs)

Andrew Huberman 1:01:41 ... he's coming for you with neuroscience-

Erich Jarvis 1:01:43 Right.

Andrew Huberman 1:01:43 ... to, to back him. Earlier you said that you discovered that you could dance. That, that caught my ear. Um, it sounds like you didn't actually have to... I'm not suggesting you didn't work hard at it but-

Erich Jarvis 1:01:55 Yeah.

Andrew Huberman 1:01:55 ... that at the moment where you discovered it, um, it just sort of was a, a skill that you had, that up until that point you didn't target a, a, a life in, in the world of dance but the fact that you "discovered" that you could dance really well-

Erich Jarvis 1:02:10 Yeah.

Andrew Huberman 1:02:10 ... and then went to this incredible school of dance and, and did well, um, tells me that perhaps there is a, an ability that was built up in childhood-

Erich Jarvis 1:02:18 Mm-hmm.

Andrew Huberman 1:02:18 ... and/or that perhaps we do all have different genetic leanings for, for different, uh, motor functions.

Erich Jarvis 1:02:25 Yeah. Well, there, for me there could be both explanations could be possible. For the first, um, yeah, I grew up in a family listening to Motown songs, you know, dancing, you know, at, uh, parties and so forth, family parties and, you know, an African American family basically and, uh, uh, so, so I grew up dancing, uh, from a young child, um, but this, th- this discovery, you know, maybe dancing even more so, uh, uh, in terms of a t- of a talent, it could... The genetic component, if it really exists, I don't know. You know, with my 23andMe, uh, results, you know, it says I have, uh, the genetic, uh, substitutions that are associated with, uh, you know, high intensity athletes and fast twitch muscles.

Andrew Huberman 1:03:12 Mm-hmm.

Erich Jarvis 1:03:13 And who knows? Maybe that could have something to do with me being able to synchronize, uh, uh, my body, uh, s- uh, to rhythmic sounds, uh, maybe, maybe better than some others. Um, it turns out that my genetics also show that I have a genetic substitute that doesn't... that makes it hard for me to sing on pitch and so that does correlate with my... You know, even though I can sing on this pitch, especially if I hear a piano, uh, or, you know, kind of playing it, but, uh, you know, maybe that's why my siblings, you know, who didn't have that genetic predisposition in his 23andMe results. You know, it could go along with the genetic, uh, component as well.

Andrew Huberman 1:03:52 I'm imagining family gatherings with 23andMe data (laughs) and-

Erich Jarvis 1:03:56 (laughs)

Andrew Huberman 1:03:56 ... and intense arguments about it.

Erich Jarvis 1:03:57 Yeah.

Andrew Huberman 1:03:58 Uh, innate and learned ability.

Erich Jarvis 1:03:59 Yes.

Andrew Huberman 1:04:00 Fun. Um, love to be, uh, in attendance at... I'm not inviting myself to your Thanksgiving dinner-

Erich Jarvis 1:04:04 (laughs)

Andrew Huberman 1:04:04 ... by the way, but I suppose I am.

Erich Jarvis 1:04:07 You're welcome to.

Andrew Huberman 1:04:08 Thank you. Uh, I'll bring my 23andMe data.

Andrew Huberman 1:04:11 I'd love to chat a moment about facial expression.

Erich Jarvis 1:04:14 Mm-hmm.

Andrew Huberman 1:04:14 'Cause that's a form of motor pattern that, you know, I think for most people out there, um, just think about smiling and frowning, but there are, of course, you know, thousands, if not millions of micro-expressions and things of that sort, many of which are subconscious, um, and we're, we are all familiar with the fact that when what somebody says doesn't match some specific feature of their facial expression that it can, um, call our... You know, that mismatch can cue our attention.

Erich Jarvis 1:04:45 Yeah.

Andrew Huberman 1:04:45 Especially among people that know each other very well.

Erich Jarvis 1:04:47 Yeah.

Andrew Huberman 1:04:47 Like, you s- somebody will say, "Well you said that but you, your right eye twitched a little, you know, a little bit in a way that tells me that you didn't really mean that." This, these kinds of things. Or when, uh, in the opposite example, when the emotionality and the content of our speech is matched to a facial expression, there's something that's just so, um, uh, wonderful about that because it seems like everything's aligned.

Erich Jarvis 1:05:13 Yeah.

Andrew Huberman 1:05:13 So how does the motor circuitry that controls facial expression map onto the m- the brain circuits that control language, speech, and even bodily and hand movements?

Erich Jarvis 1:05:23 Yeah. Uh, you, you, and you ask a great question because we both know some colleagues like Winrich Freiwald at, uh, Rockefeller University who study facial expression and the neurobiology behind it, and now we both share some students that we're co-mentoring, and talk about this same question that you brought up, and what I'm learning a lot is that non-human primates have a lot of diversity in their facial expression like we humans do. And what we know about the neurobiology of brain regions controlling those muscles of the face is that these non-human primates and some other species that don't learn how to imitate vocalizations, they have s- strong connections from the cortical regions to the motor neurons that control facial expressions, but absent connections or weak connections to the motor neurons that control the voice. So I think our diverse facial expression, even though it's more diverse in these non-human primates, there was already a preexisting diversity of communication, whether it's intentional or unconscious through facial expression in our ancestors, and on top of that, we humans now add the voice, uh, along with those facial expressions.

Andrew Huberman 1:06:38 I see. The... And i- in terms of language learning when we're kids, I mean, I d- children fortunately are not told to fake their expressions or to smile when they say, "I'm happy."

Erich Jarvis 1:06:48 Mm-hmm.

Andrew Huberman 1:06:48 Um, so at some point everybody learns, for better or for worse, how to, uh, untangle these different components of hand movement, bo- body posture, speech and facial expression.

Erich Jarvis 1:07:01 Mm-hmm. Yes.

Andrew Huberman 1:07:02 But in it- in their best form I would say, um, assuming that the best form is always... I guess there are instances where, you know, for safety reasons one might need to feign some of these, uh, (laughs) some of these aspects of language, but in most cases when those are aligned, um, it seems like...... that could reflect that all the different circuitries are operating in parallel, but that the, the ability to misalign these is also, uh, a powerful aspect to our maturation. I, I even think of theater, for instance, where deliberate disentangling of, of these areas is important, but also we know when an actor i- when it feels real-

Erich Jarvis 1:07:40 Yep.

Andrew Huberman 1:07:41 ... um, and when it looks like... When bad acting is oftentimes when the facial expression or body posture just doesn't quite match what we're hearing.

Erich Jarvis 1:07:48 Yeah.

Andrew Huberman 1:07:48 Uh, so are these skills that, that people... That learn and acquire according to adaptability and profession, or do you think that all children and all adults eventually learn how to couple and uncouple these circuits a little bit?

Erich Jarvis 1:08:02 Yeah. Yeah, I, I think it's, it's the si- similar argument I mentioned earlier about the innate and learned for the vocalizations, and by the way, when I say fa- we humans have facial expressions associated with our vocalizations in a different way than primates, non-human primates, it's the learned vocalizations I'm talking about. So there is a common view out there that facial expressions in non-human species, like non-human primates, or you can have them in birds too-

Andrew Huberman 1:08:30 (laughs) .

Erich Jarvis 1:08:30 ... are, um, innate, all right? And so they're n- they're c- they're reflexive, controlled. I don't believe that. I think there's some learned component to it, and I think we have more learning component to it as well, but we also have an innate component. And so if you try to put your hands behind your back and, and hold your fists or even just not and try to speak and try to communicate, it's actually harder to do. You have to force yourself or put it by, by your side. This comes naturally. Facial expressions comes naturally because there is an innate component and yes, you have to learn how to dissociate the two. Communicate something angry with your hands or with your face, but, um, you know, uh, politely with your voice. It's very hard to distin- to separate out those two because there is that innate component that brings them together. Um, so it's like an email too. You're, you're emailing and someone says something by email. Someone can interpret that angrily or, or gently, uh, and it, it bec- becomes ambiguous. The facial expressions get rid of that ambiguity.

Andrew Huberman 1:09:35 I'm so glad you brought that up because my next question was and is about written language. Uh, the first question I'll ask is when you write, either type or write things out by hand, do you hear the content of what you want to write in your head? You, just you personally.

Erich Jarvis 1:09:54 Yes, I do.

Andrew Huberman 1:09:55 Mm-hmm.

Erich Jarvis 1:09:55 Yeah, I, I, I... And I know that I do because I was trying to figure out a debate about this issue and trying to resolve the debate with my own self-experimentation on me.

Andrew Huberman 1:10:09 I ask that because a, a quite well-known colleague of ours, Karl Deisseroth at Stanford who's been on this podcast and is, you know, of optogenetics fame and psychiatry fame, et cetera-

Erich Jarvis 1:10:18 Yeah, and I, I know him.

Andrew Huberman 1:10:19 Yeah-

Erich Jarvis 1:10:20 (laughs) .

Andrew Huberman 1:10:20 Um, he sends his regards, so yeah.

Erich Jarvis 1:10:22 Okay, thank you. (laughs) .

Andrew Huberman 1:10:22 Uh, told me that, um, his practice for writing and for thinking involves a, a quite painful, um, process of forcing himself to sit completely still and think in complete sentences, to force thinking in complete sentences.

Erich Jarvis 1:10:40 Mm-hmm.

Andrew Huberman 1:10:40 And when he told me that, I decided to try this exercise and it's quite difficult. First of all, it's difficult for the reason that you mentioned, which is that with many thoughts I want to look around and I start to gesticulate with my hands.

Erich Jarvis 1:10:51 Mm-hmm.

Andrew Huberman 1:10:52 All right, so there it is again, the connection between language and hand movement even if one isn't speaking. The... And the other part is that I... That's challenging is I realize that while we write in complete sentences most of the time, we'll talk about how that's changing now-

Erich Jarvis 1:11:08 Right.

Andrew Huberman 1:11:08 ... and texting, et cetera, that we don't often think in complete sentences and specifically in simple declarative sentences.

Erich Jarvis 1:11:18 Mm-hmm.

Andrew Huberman 1:11:18 That a lot of our thoughts would be if were... If they were written out onto a page would look pretty much like passive language that a good copy editor or a good editor would say, "Ugh, like, we need to cross this out, make this simple and declarative." So what I'm getting at here is what is the process of going from a thought to language to written word? And I also wanted to touch on handwritten versus typed, but thought to language to written word. What's going on there? What do we know about the neural circuitry? And I was going to ask why is it so hard, but now I want to ask why is this even possible? It seems like-

Erich Jarvis 1:11:59 (laughs) .

Andrew Huberman 1:11:59 ... a very challenging neural computational problem.

Erich Jarvis 1:12:02 Yeah, yeah, and, and from coming from the linguistic world or and even just the regular neurobiology world, the... Going back to something I said before is about a separate language module in the brain. You know, there was this thought or hypothesis that this language module has all these complex algorithms to them and they're signaling to the speech circuit how to produce the sounds, the hand circuit how to write them or gesture, uh, the visual pathway on how to interpret them from reading, uh, and the auditory pathway for listening. I don't think that's the case, all right? Uh, and, you know, that this thinking where, where there's this internal speech going on. What I think is going on is, to explain what you're asking, is about... That I'm going to take it from the perspective reading something. You read something on a paper. The signal from the paper goes through your eyes. It goes to the back of your brain to your visual cortical regions eventually, uh, and then you now got to interpret that signal in your visual pathway of what you're reading. How are you gonna do that in, in terms of speech? That visual signal then goes to your speech pathway in the motor cortex and front here in Broca's area and you silently speak what you read in your brain without moving your muscles.... and sometimes, actually, if you put electrodes, E- EEG, uh, EMG electrodes on your lor- lar- laryngeal muscles, even on words you can do this, you'll see activity there while reading or- or- or trying to speak silently, even though no sound's coming out. And so, your speech pathway is now speaking what you're reading. Now, to finish it off, that signal is sent to your auditory pathway so you can hear what you're speaking in your own head.

Andrew Huberman 1:13:53 That's incredible.

Erich Jarvis 1:13:54 And this is why it's complicated, because you using, like, three different pathways, the visual, the speaking motor one, and the auditory to read. Oh, and then you got to write, right? Okay, here comes a fourth one. Now, the hand areas next to your speech pathway has got to take that auditory signal, or even the adjacent motor signals for speaking, and translate it into a visual signal on paper. So y- so you're using at least four brain circuits, uh, which includes the speech production and the speech perception pathways to write.

Andrew Huberman 1:14:28 Incredible. And finally explains to me why when I ... So, I was weaned teaching undergraduates, graduate students, and medical students, and I've observed that when I'm teaching, I have to stop speaking if I'm going to write something on the board.

Erich Jarvis 1:14:44 Mm-hmm.

Andrew Huberman 1:14:44 I just have to stop all speaking, completely.

Erich Jarvis 1:14:46 Right.

Andrew Huberman 1:14:47 Turns out this is an advantage to catch, because it allows me to catch my voice, it allows me to slow down a bit, um, you know, breathe and inhale some oxygen (laughs) and so on, because I tend to speak quickly if I'm not writing something out. So, uh, there's a break in the circuitry for me, or at least they are distinct enough that I have to stop and then write something out.

Erich Jarvis 1:15:06 Yes, that- that- that- that does imply competing brain circuits for your conscious attention.

Andrew Huberman 1:15:13 We have colleagues, um, up at Columbia Med who are known, at least in our circles, for dictate, voice dictating their papers. Not writing them out-

Erich Jarvis 1:15:23 Mm-hmm.

Andrew Huberman 1:15:23 ... but just speaking into a voice recorder. Uh, I've written papers that way. It doesn't feel quite as natural for me as writing things out-

Erich Jarvis 1:15:32 Yeah.

Andrew Huberman 1:15:32 ... but not because I can go quickly from thought to language to typing. I type reasonably fast. I can touch type now. I don't think I ever taught my ... I- I think I taught myself. I never took a touch typing course.

Erich Jarvis 1:15:43 Yeah.

Andrew Huberman 1:15:43 It just sort of happened. Now, I think my motor system seems to know where the keys are with enough, uh, uh, enough accuracy that it works. The, this is remarkable to me that any of us can do this, but when it comes to writing, what I've found is that if my rate of thought and my rate of writing are aligned nicely, things go well. Uh, however, if I'm thinking much faster than I can write, that's a problem, and certainly, if I'm thinking more slowly than I want to write, that's also a problem.

Erich Jarvis 1:16:17 Mm-hmm.

Andrew Huberman 1:16:18 And the solution for me has been to write with a pen. I'm in love with these, and I have no relationship to the company, at least not now, although if they want to come, uh, you know, if they want to work with us ... I love these Pilot V5-V7s because not necessarily because of the ink or the- the feel, although I like that as well, but because of the rate that it allows me to write. They write very well slowly, and they write very well quickly.

Erich Jarvis 1:16:40 Mm-hmm.

Andrew Huberman 1:16:40 And so I've, have this theory supported only by my own anecdata, no peer-reviewed study, that ha- writing by hand is fundamentally different than typing out information.

Erich Jarvis 1:16:55 Mm-hmm.

Andrew Huberman 1:16:55 Is there any evidence that this motor pathway for writing is better th- or somehow different than the motor pathway for- for typing?

Erich Jarvis 1:17:07 Yeah, that- that's interesting. Um, and I don't know of any studies. Um, I have my own personal experience as well, but trying to put this into the context, if I had to, you know, design an experiment to test a hypothesis here that, you know, to explain your experience and mine is that writing by hand, I'm, I would argue, uh, requires a different set of le- less skills with the fingers-

Andrew Huberman 1:17:33 Mm-hmm.

Erich Jarvis 1:17:33 ... than typing. So you ha- you have to coordinate your fingers more in opposite directions and so forth, uh, with typing. Uh, but also writing by hand requires more arm movement, uh, and so therefore, I would argue that the, um, the- the difficulty there could be in the types of muscles, uh, and the fine motor control you need of those muscles along with speaking in your brain at the same time.

Andrew Huberman 1:18:02 So basically, I'm coarse, I'm a brute-

Erich Jarvis 1:18:04 Right, right, right.

Andrew Huberman 1:18:04 ... and so it makes sense that I would-

Erich Jarvis 1:18:05 That's-

Andrew Huberman 1:18:05 ... a per- more primitive writing device would work.

Erich Jarvis 1:18:08 That's right, yes.

Andrew Huberman 1:18:09 Yeah.

Erich Jarvis 1:18:09 But- but let me, let me add to this in terms of the, um, I, in my own personal experience, right? What I find is I can write, I can write something faster by hand, um, for a short period of time compared to typing, and that is because I think I- I run out of the energy in my arm movements, uh, faster than I run out of muscle energy in my finger movements. Uh, and w- I think it takes a longer time for us to write words with our fingers, uh, because an- in terms of the speech. So I think your writing, whether it's by hand or typing, and your speech, they only will align very well if you can type as fast as you can speak or write as fast as you can speak in your head.

Andrew Huberman 1:18:56 Ah, I love it.

Erich Jarvis 1:18:57 Yeah.

Andrew Huberman 1:18:57 So what you've done, if I understand correctly, is created a bridge between thought and writing-

Erich Jarvis 1:19:02 Mm-hmm.

Andrew Huberman 1:19:02 ... and that bridge is speech.

Erich Jarvis 1:19:04 That bridge is speech, that's right. That's right. When you're writing something out, you're speaking it to yourself, and if you're speaking faster than you can type, you got a problem. (laughs)

Andrew Huberman 1:19:15 Interesting. I, uh, I do a number of podcast episodes that are not with guests but solo episodes, and as listeners know, these are very long episodes, often two or more hours.And, um, we joke around the podcast studio that I- I will get locked into a mode of speech where some of it is more elaborative and, um, anecdotal and then I'll- and then I'll punch out, um, simple declarative sentences. I find it very hard to switch from one module to the next. The thing that I have done in order to, um, make that transition more fluid and prep for those podcast episodes is actually to read the lyrics of songs-

Erich Jarvis 1:19:53 Mm-hmm.

Andrew Huberman 1:19:53 ... and to sing them in my head as a way of warming up my vocal cords but, um, luckily for those around me, uh, when I do that, I'm not actually singing out loud.

Erich Jarvis 1:20:03 Mm-hmm.

Andrew Huberman 1:20:03 And so this, uh, what you're telling me, um, supports this idea that even when we are imagining singing or writing in our mind, we are exercising our vocal cords.

Erich Jarvis 1:20:16 You- you're actually getting little low potentials of electrical currents reaching your muscles there which also means you're exercising your speech brain circuits too without actually, you know, going with the ... [inaudible] activity in the muscles.

Andrew Huberman 1:20:29 Incredible.

Erich Jarvis 1:20:30 Yeah. And this- this idea of singing helps you as well, uh, um, uh, even with Parkinson's patients and so forth when they want to say something, singing or listening to music helps them move better and the idea there is that the brain circuits for singing or let's say the function of the brain circuits for speech being used for singing first is the more ancestral trait and that's why it's easier to do things with singing sometimes than it is with speaking.

Andrew Huberman 1:20:56 I love it.

Andrew Huberman 1:20:58 Stutter is a, um, particularly interesting case and- and one that, uh, every once in a while I- I'll get questions about this from our audience. Um, stutter is- is complicated in- in a number of ways but culturally, um, and my understanding from these emails that I receive is that, um, stutter can often, um, cause people to hide and speak less.

Erich Jarvis 1:21:19 Mm-hmm.

Andrew Huberman 1:21:20 Because it can be embarrassing and we're- we are often not patient with- with stutter. We also have the assumption that if somebody's stuttering that their thinking is slow but it turns out there are many examples historically of people who could not speak well but who were brilliant thinkers.

Erich Jarvis 1:21:35 Mm-hmm.

Andrew Huberman 1:21:35 Um, I don't know how well they could write but, um, they found other modes of communication. Uh, I realize that you're not a- a speech pathologist and- or therapist but, uh, what is the current neurobiological understanding of stutter and are, uh, what's being developed in terms of treatments for stutter?

Erich Jarvis 1:21:53 Yeah, so w- we actually, uh, accidentally came across stuttering in songbirds and we've, uh, published several papers on this to try to figure out the neurobiological basis. The first study we had was a brain area ca- uh, called the basal ganglia or the s- what's the- the striatum part of the basal ganglia involved in coordinating movements, learning how to make movements. When it was damaged in these- in this- in the speech-like pathway in these birds, what we d- found is that they started to stutter as the brain region recovered. And unlike humans, they actually recovered after three or four months and why is that the case? Because bird brains undergoes new neurogenesis in a way that, uh, human or mammal brains don't. Uh, and it was the new neurons that were coming in, into the circuit, uh, but not quite, you know, with the right proper activity, uh, was resulting in this stuttering in these birds. Uh, and after it was repaired not exactly the old song came back as a r- after repair but still it recovered a lot better. And it's now known, they call this neurogen- neurogenics stuttering in humans, uh, with da- damage to the basal ganglia or some type of disruption to the basal ganglia at a young age also causes stuttering in humans. And even those who are born with stuttering, uh, um, it's- it's often the basal ganglia, uh, that's disrupted than some other brain circuit and we think the speech part of the basal ganglia.

Andrew Huberman 1:23:29 Can adults who maintain a stutter from childhood, uh, repair that stutter?

Erich Jarvis 1:23:34 They can repair it with, uh, therapy, with learning how to speak slower, uh, learning how to tap out a rhythm during st- And yeah, I'm not a speech pathologist but I started reading this literature, uh, and talking to others that, you know, um, colleagues who actually study- study stuttering. So yes, there- there- there are ways to overcome the stuttering through, um, through, uh, you know, behavioral therapy. Uh, and I think all of th- the, uh, tools out there have something to do with sensory motor integration. Uh, controlling what you hear with what you output in a, uh, thoughtful controlled way helps reduce the stuttering.

Andrew Huberman 1:24:15 There are a couple of examples from real life that I want to touch on and, um, one is somewhat facetious but, um, but now I realize is- is a serious neurobiological issue. Serious meaning I think interesting which is that every once in a while I will have a conversation with somebody who says the last word of the sentence along with me.

Erich Jarvis 1:24:36 Mm-hmm.

Andrew Huberman 1:24:37 And it seems annoying in some instances, uh, but I'm guessing this is just a breakthrough of the motor pattern that they're hearing what I'm saying very well, so I'm going to interpret this kindly and think they're hearing what I'm saying, they're literally hearing it in their mind-

Erich Jarvis 1:24:52 Mm-hmm.

Andrew Huberman 1:24:53 ... and they're getting that low level electrical activity to their throat and they're just joining me in the, uh, in the enunciation of what I'm saying probably without realizing it. Is- can we assume that that might be the case?

Erich Jarvis 1:25:06 Well, I- I- I wouldn't be surprised so th- you know, the motor theory of speech perception where this idea originally came, what you hear is going through your speech circuit and then also activating those muscles slightly. Uh, so yes, um, so one might argue okay, is that speech circuit now interpreting what that person is speaking now you listening to me?... and is going to finish it off because it's already going through their brain-

Andrew Huberman 1:25:33 Mm-hmm.

Erich Jarvis 1:25:34 ... and they can predict it. That would be one, one theory. And, and I don't think the verdict out there is no, but that's one. The other is, uh, synchronizing turn-taking in, in the con- in the, um, conversation, where you're acknowledging that we understand each other, uh, by finishing off what I say. Uh, and it's almost like a social bonding kind of thing. The other could be, I want the person to shut up so I can speak as well and take that turn. And, and each pair of people have a rhythm to their conversation, and if you have somebody who's over-talkative versus under-talkative or vice versa, that rhythm can be lost in them finishing ideas and going back and forth. But I, I think, uh, having something to do with turn-taking as well makes a lot of sense.

Andrew Huberman 1:26:22 I have a colleague at Stanford