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

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Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. I’m Andrew Huberman and I’m a professor of neurobiology and ophthalmology at Stanford School of Medicine. And now, for my discussion with Dr. Eric Jarvis. Eric, so great to have you here.

Thank you. >> Yeah. Very interested in learning from you about speech and language. 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? >> There really isn’t such a sharp distinction.

Now, let me tell you how some people think of it now. That there’s a separate language module in the brain 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, sound that we call speech. 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, sientese, 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. >> What do we understand about modes of communication that are like language, but might not be what would classically be called language?

So, 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. Humans are the most advanced at spoken language, but not necessarily as big a difference at gestural language compared to some other species. 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, or doing it unconsciously.

And if we were talking on a telephone, I would have one hand here and I’d be gesturing with the other hand uh without even you seeing me, right? And so, why is that? Uh some have argued, and I would agree with 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 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 sign 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 to 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.

One thing that I’ve wondered about for a very long time is whether or not primitive emotions and primitive sounds are the early substrate of language. When I smell something delicious, I typically inhale more and I might say or something like that. Whereas if I smell something putrid, I typically turn away, I wince, and I will exhale trying to not ingest those molecules or inhale those molecules. I could imagine that these are the basic dark and light contrasts of the language system. Is this kind of primitive to more sophisticated pyramid of of sound to language?

Is this a crazy idea? Do we have any Do we have any evidence this is the way it works? >> 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 had started out in, which is vocal learning research. Most vertebrate species vocalize, but most of them are producing innate sounds that they’re born with, that is babies crying, for example, or dogs barking. And only a few species have learned vocal communication, the ability to imitate sounds.

And that’s is what makes spoken language special. When people think of what’s special about language, it’s the learned vocalizations. That is what’s rare. So, all the things you talked about, the breathing, the grunting, and so forth, a lot of that is handled by the brainstem 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 a 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. >> Do we have any sense of when modern or sophisticated language evolved?

Amongst the primates, which we humans belong to, we are the only ones that have this advanced vocal learning ability. Uh Now, when you 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. 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, where we can look at genes that are involved in learn 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. >> Maybe we could talk a little bit more about the overlap between brain circuits that control language and speech in humans and other animals. You know, I was weaned in the neuroscience era where bird song and the uh the ability of birds to learn t