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

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. Erich Jarvis. Erich, 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, s-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 this 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, [foreign language] , 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?

Yes. Right. 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. We're doing it unconsciously. And if we were talking on a telephone, I would have one hand here, and I would be gesturing with the other hand [laughing] 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, [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, Coco, a gorilla who was raised with humans for thirty-nine years or more, uh, learned how to do gesture communication, learned how to sign language, so to speak, right? But Coco couldn't produce those sounds. Coco could understand them as well by si- by seeing somebody sign or hearing somebody produce speech, but Coco 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.