Understanding and Treating Stuttering

Welcome to Huberan 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. Eddie Chang Edy, welc Hi Andrew Its great to be here with you. Your main focus these days is the neurobiology of speech and language. So for those that aren't familiar, could you please distinguish for us speech versus language in terms of whether or not different brain areas control them? When I think about language, I think about words and just talking If I sit down to do a long podcast or I think about asking you a question, I don't even think about the words I want to say very much. I mean, I have to think about them a little bit. One would hope But I don't think about individual syllables unless I'm trying to, you know, accent something or it's a word that I have a particular difficulty saying where I want to change the cadence, etcera What in the world is contained in these brain areas, what is represented to me is Phaps one of the most interesting questions, and I know this lands square in your wheelhouse. Sure Let's get into this, Andrew, because this is one of the most exciting stuff that's happening right now is understanding how the brain processes these exact questions. and speech corresponds to The communication signal corresponds to me moving my mouth and my vocal track to generate words And you're hearing these is an auditory signal Language is something much broader. So it refers to what you're extracting from the words that I'm saying. We call that pragmatics and sort of are getting the gist of what I'm saying There's another aspect of it that we call semantics. Do you understand the meaning of these words and h the sentences There's another part that we call syntax, which refers to how the words are assembled. in a grammatical form. So those are all really critical parts of language And speech is just one form of language. There's many other forms like sign language reading, those are all important modalities for reading Our research really focuses on this area that we're calling speech. againgain, the production of audio signal which you can't see but your microphones are picking up There were these vibrations in the air. that are created by my vocal track that are picked up by the microphone. in the case of this recording, but also picked up by the sensors in your ear. the very tiny vibrations in your ear are picking that up and translating that into electrical activity. It's such a complex feat. Some people would say, it's the most complex motor thing that we do as a species is is just speaking not, you know, the extreme feats of acrobatics or athleticism, but and especially speaking. And especially when one observes, you know, opera or people who, you know, freestyle rappers, you know, and of course, it's not just the lips It's the tongue Yeah. And you've mentioned two other structures. Pharynx and larynx are the main ones that can you tell us just educate us at a superficial level what the phharynx and larynx do differentially because I think most people aren't going to be sureure. I'll talk primarily about the larynx here for a second, which is that If you think about when we're speaking, really what we're doing is we're shaping the breath. So even before you get to the larynx, you got to start with the expiration We fill up our lungs and then we push the air out. That's a normal part of breathing. What is really amazing about speech and language is that we evolved to take advantage of that normal physiologic thing. A of larynx And what the larynx does is that When you're exhaling, it brings the vocal folds together Some people call them vocal chords. They're not really cords. They're really Vocal folds, they're two pieces of tissue that come together and a muscle brings them together. And then what happens is when the air comes through the vocal folds when they're together, they vibrate at really high frequencies, like one hundred to two hundred hertz. And the reason why men and women generally have different voice qualities is it has to do with the size of the larynx. in the shape of it Okay, so in general, men have a larger Voice box or larynx. and the vibrating frequency, the resonance frequency of the vocal folds when the air comes through them is about one hundred herz for men and about two hundred for women So you take a breath in As the error is coming out The vocal folds come together The air goes through, that creates the sound of the voice that we call voicing. It's not just your voice characteristic, it's the energy of your voice is coming from the larynx there It's a noise. and then it's the source of the voice And then what happens is that energy, that sound goes up through the parts of the vocal track, like the phharynx into the oral cavity, which is your mouth and your tongue and your lips. And what those things are doing is that they're shaping the air particular ways that create Conants and vowels. That's what I mean by shaping the breath. It just starts with this exhalation You generate the voice in the larynx And then everything above the larynx is moving around justust like the way my mouth is doing right now to shape that error particular patterns that you can hear is words immediately makes me wonder about more prrimitive or non learned Vocalizations like crying or laughter A those produced by the language areas or do they have their own unique neural structures? We call those vocalizations. A vocalization is basically where someone can create a sound like a cry. or a moan That kind of sound and also involves the excealation of air It also involves some phonation at the level of larynx where the vocal volts come together to create that audible sound. But it turns out that those are actually different areas. So people who have injuries in the speech and language areas oftentimes can still moan, they can still vocalize. And it is a different part of the brain. I would say an area that even non human primates have that can be specialized, you know for vocalization. It's a different form of communication than words, for example. I'd like to take a quick break and acknowledge our sponsor, Fction Function provides over one hundred and sixty advanced lab tests to give you a clear snapshot of your bodily health This snapshot gives you insights into your heart health, your hormone health, autoimmune function, nutrient levels, and much more. They've also recently added access to advanced MRI and CT scans. Function not only provides testing of over one hundred and sixty biomarkers key to your physical and mental health It also analyzes these results and provides recommendations for improving your health from top doctors. For example, in a recent test with function, I learned that some of my blood lipids were slightly out of range. As a result, I decided to start supplementing with natokinase, which can naturally help reduce LDL cholesterol And it did. In a follow up test, I could confirm that this strategy worked. My blood lipids are now back exactly where I want them Comprehensive lab testing of the sort that fununction offers is just so important for health. I mean, how else are you going to know what's going on under the hood And while I've been doing bloodwork for years, it used to be time consuming, complicated, and expensive. In fact, I used to spend thousands of dollars per year trying to get this kind of data. and the data, frankly, were not all that good But now with function, it's extremely easy and affordable A function membership is only a dollar a day, three hundred and sixty five dollars a year. And if you think about the information it provides and the health challenges it helps you avoid and the proactive things that it can do for you to enhance your health, I truly look at it as a savings. To learn more, visit functionhealth dot com slash hubberman and use the code Hubberman for a fifty dollar credit towards your membership Again, that's functionhealth dot com slash Hubberan Speaking of storage of and ability to speak, you are doing some amazing work achieved some incredible well deserved recognition for your work in bringing language out of paralyzed people. essentially allowing people who are locked in a paralyzed state or otherwise unable to articulate speech using brain machine interface essentially translating the neural activity of areas of the brain that produce speech. into hardware artificial non biological tools in order to allow paralyzed people to communicate. So there are a series of conditions They include things like brainstemem stroke. The brainstemem is the part of the brain that connects The cerebrum, which is the top part does our thinking and A lot of the motor control, speech, language, everything. And the brain system is what connects that to the spinal cord and the nerves that go out to the face and vocal tracts. So if you have a stroke there You could be thinking all the wild creative, intelligent thoughts you have in the mind in the cerebrum, but you can't get them out into words, or you can't get them out to your hand to write them down. So that's a very severe form of paralysis called brainstemstem stroke. There's another kind of conditions that we call neurodegenerative where the nerve cells die basically or atrophy in a condition called AS That's a very severe form of paralysis. In its extreme form people essentially lose all voluntary movement. The muscles to their diaphragm and their lungs essentially give out as well as they get weakness there and then they can't breathe anymore In our field, these are kind of like the most devastating things that can happen This condition of what we call being locked in refers to this idea that you can have completely intact cognition. and awareness, but have no way to express that. No voluntary movement no ability to speak. and that is devastating because psychologically and socially, you know, you're completely isolated That's what we call locked in syndrome And it's devastating. So We've been studying this patterning of electrical activity for consonants and valves. Essentially once we figured out a lot of these codes for individual phonetic elements, part of the lab started to focus on this very specific question For people who have these kind of paralysis, could we Intercept those signals. from the brain, the cerebral cortex As someone is trying to say those words And then can we intercept them and then have them taken out of the brain through wires to a computer that are going to interpret those signals and translate them into words. So We started a clinical trial. It's called the Bravo trial. It's still underway. And the first participant in the Bravo trial was a man who had been paralyzed for fifteen years. He was in a car accident. He actually walked out of the hospital day after that car accident, but the next day had a complication related to it where he had a very large stroke in the brainstem And that turned out to be devastating You didn't wake up from that stroke for about a week. He was in a coma for about a week And when he woke up from that coma, he realized that he couldn't speak or move his arms or legs. As he told me or communicated to us, that was absolutely devastating. He wanted. really to die at that time. Could he blink his eyes or move his mouth in any way? He could blink his eyes. He had some limited mouth movements but couldn't produce any intelligible spe was like completely slurred and incomprehensible He survived this injury. A lot of people who have that kind of stroke just don't survive. The way he actually communicates because he has a little bit of residual neck move is that He improvised and had His friends basically a stick attached to his baseball cap. Because he could move his neck, he would essentially type out letters on a keyboard screen to get at words. In fact, this is how he communicated was through a device that he would essentially pck out letters one by one by moving his neck to control the stick attached to his baseball cap. He hadn't really spoken for about fifteen years. Oh goodness. Yeah. So it was part of a clinical trial. It was, you know, something that our hospital And also the FDA, had to approve and looked at very carefully. But given a lot of the work that we had done There was some basis for why this might work. And so we did a surgery where we implanted electrodes to these areas that control the vocal trg, the areas that control the larynx, the areas They control the lips and tongue and jaw movements when we normally speak. These are areas that presumably may be active. That was our hope And he underwent a surgery, a brain surgery. We put an electrode array and we connected it to a port that was skulled to screw to his skull. And the port actually goes through his scalp, and he's lived with this now for the last three years So he has an electrode array that's implanted over the part of the brain that's important for speech. It's connected to a port And then we connect a wire to that port that translates those what we call analog, you know, brainwaves and converts them into digital signals with them through machine learning or artificial intelligence algorithm that can pick up these very, very subtle You can't actually see them with your eye in the brain activity and translate those into words And this is something that took weeks to train the algorithm to interpret it correctly. But what was incredible about it was to see how he reacted. He would be prompted to say a given word like, you know, outside, for example and You would think about it, try to say it, and finally those words would appear. on the screen and what was really amazing about it was you could really tell that he like got a kick out of it because you know, his body would shakeen away and his head would shaken away that he would start to giggle. That was cool to see. but then I also realized that when he was giggling, it kind of screwed up the next words decoding. Is that a bug you've since fixed? No, we haven't fixed that. It's easier just to tell him to stop giggling. The way this worked was we trained This computer will recognize fifty words. We started with a very small vocabulary that's expanding as we speak. I think that this is just a matter of time before. These vocabulies become much, much larger But we started with a fifty set of words. We created essentially all the possible sentences that you could generate from those fifty words. Why that was important was You can use all those possible sentences to create a computational model, computer model all the different word combinations to give different sentences given those fifty words. and then you can essentially do What we call autocorrect. It's the same kind of thing that we do when you're texting, for example, you get the wrong letter in there. yourour phone actually knows, you know, because it's context, what corrected So because the decoding is not one hundred percent correct, all the time in fact, it's far from that It's really helpful to have these other features like autocorrect, the stuff that we use routinely now with texting that makes it correct and then updates it. So it's a combination of a lot of things. It's the AI that is translating those brain activity patterns, but it's also things that we've learned from speech and speech technologies You know, you put all together and then all of a sudden it starts to work. That was the first time that someone was paralyzed and could words in sentences that was just decoded from the brain activity I'd like to take a quick break and acknowledge our sponsor, Better Help Better Help offers professional therapy with a licensed therapist carried out entirely online. I've been doing therapy for a long time, and I can tell you that it's a lot like physical workouts. There are times when I want to do it, and there are times when I don't want to do it. But whenever I finish a therapy session I come away feeling better and I have specific actionable items that hadn't occurred to me that when I implement improve various aspects of my life. The data tell us that there are just so many benefits that come through effective therapy. And effective therapy involves having good rapport with your therapists, getting insights from them and with them, and coming away with specific actionable tools that you can apply outside of therapy With better helpel, they make it very easy to find an expert therapist who can help provide those benefits that come through effective therapy. And the data say it works BetterHelp has an average rating of four point nine out of five for its live sessions based on over one point seven million client reviews. Also because Better Help is done entirely online, it's extremely efficient. There's no driving to a therapist's office looking for parking or anything like that. You simply log on and do your session wherever you happen to be If you would like to try Betterhelp, go to betterterhelp dot com slash Hubberman to get ten percent off your first month. Again, that's betterhelp dot com slash hubberman These days we hear a lot about neural link Elon Musk's compomany. while brain machine interface of the sort that you do and that other laboratories do has been going on for a long time there's been some press around neeuralink promise of what brain machine interface could do. What are your thoughts about manipulating neural circuitry to achieve superra human or superhan or supra physiological functions. And here we don't even have to think about neuralink in particular. It's just but one example companies and people in laboratories that are quuite understandably considering all this It's a really interesting time right now. The science has been going on for decades. The work that we've done in this field that you call Brain Machine interface It's been going on for a while and A lot of the early work was just trying to restore things like our movement or having people or monkeys control a computer cursor, for example on a screen that's been going on for decades. What's been really new is that industry is now involved and some of this is now becoming commercialized and we're starting to see Let's now cross over to this field where it's no longer just research that we're talking about medical products that are designed to be, you know surgically implanted In some cases, you know, there's people doing this kind of work non invasively as well that don't require surgery. The specific question that you were asking about is an area that we call augmentation. So can you build a device that essentially enhances someone's ability beyond superra normal suuper memory. super communication speeds beyond speech, for example. superior Oh precision, athletic abilities. I think that these are very serious kind of questions to be asking now because as you mentioned, way so far is really to focus on these medical applications I personally don't think that we've thought enough actually about what these kind of scenarios are going to look like And I don't think we've thought through all the ethical implications of what this means for augmentation in particular. There's part of this that is not new at all humans throughout history We've been doing things to augment our function coffee, nicotine, all kinds of medications that cross over from medical to consumer that is everywhere. So the pursuit of augmentation performance or enhancement is really not a new thing The questions really, as they relate to neurotechnologies, for example, have to do W The invasive nature, for example, if these technologies require surgery, for example, to do something that is not for a medical application Again, there, that is not exactly new territory either People do that routinely for cosmetic procedures for physical appearance, not necessarily cognitive. So I do think that provided The technology continues to emerge the way that it does that It's going to be around the corner And it probably is not going to be in ways that are super obvious. I don't think it's going to be like Can we easily memorize every fact in the world? But in forms that are going to be much more incremental and maybe more subtle, in many ways, we already have that now. like for example, you don't have to have a neural interface embedded in your brain to get information essentially access to all information in the world. You just have to have, your iPhone. whether you could do it faster through a brain interface, I definitely wouldn't rule that out. But think about this the systems that we have already to speak and to communicate have evolved over you know, thousands and millions of years and they're supported by neural structures that have bandwidth of millions of neurons There is no technology that exists right now that people are thinking about that are in commercial form, certainly notot even in research labs that come anywhere close to what has been evolved for those natural purposes So I'm essentially saying twowo sides of this, which is we're already getting into this now. This is not new territory. This topic of augmentation, both physical and cognitive, we've already surpassed that. That's part of what humans do in general We are entering this area of like Enhance cognition these areas that I think the technology is going to be the r limiting step in how far go and we have not had the full conversations about number one, is this what we actually want? Is this going to be good for society? Who gets access? to this technology. These are all things that are going to become real world problems. Could you tell us what you're doing in terms of merging the brain machine interface with extraction of speech signals from people who are locked in like Poncho with facial expressions. Sure. Yeah. I'm here with you in person. We could have done this virtually, probably. It's pretty easy to do that. We could have recorded this really separate, but there is something about being able to actually see your expressions and to understand other forms of communication. So another really important one is non verbal expressions that you're making. For example, if you have a quizzical look on your face, if I'm saying something not clear That's a sign to me that I need to rephrase it or just say in a different way or slow down Facial expressions actually are a really important part of the way we speak. and there's two things It's not just the expressions of like how you're feeling and perceiving what I'm saying but it's also seeing my mouth move. In your eyes actually seeing my mouth move and my jaw move in a particular way that actually allows you to hear those sounds better Having both the visual information, but also the sounds go into your brain is going to improve intelligence reallyly, also make it more natural. And the reason why we're also very interested in this idea of not just having text on a screen, but essentially a fully computer animated face like an avatar of person's speech movements and their facial expressions is going to be a more complete form of expression Now, you can imagine right now That might just be someone looking at a computer screen interpreting these signals. but I think the way things are going. In the next couple of years, a lot more of our socialcial interactions, more than even now are going to move into this digital virtual space Of course, most people are thinking about what that means for most consumers But it also has really important implications for people who are disabled, right? And whether how are they going to participate in that And so we were thinking really about for people like Punch and other people who are paralyzed other forms of BCI can we do in order to help improve their ability to communicate? So one is essentially building out more holistic avatars, know things that can essentially decode, you know, essentially their expressions or the movements associated with their mouth in Ja when they actually speak to improve that communication So do you envision a time not too long from now where instead of tweeting out something in text, my avatar will I'll type it out, but my avatar will just say it. It'll be an image of my avatar saying whatever it is I happen to be tweeting at that moment. That's what we're working on That is going to happen and it's going to happen soon and There's a lot of progress and that and again, we're just trying to enrich Um, the the field of you know, of communication expression make it more normal. And we actually think that having that kind of avatar is a way getting feedback to people learning how to speak through a speech neuroprosthetic, that's the device that we call it, it's a speech neuroprosthetic. That is going to be the way that can help people learn how to do it the quickest, not necessarily like trying to say words and having it come on a screen actually have people embody feel like it's part of themselves or that they are directly controlling that that illustration or animation As many of you know, I've been taking AG one for nearly fifteen years now I discovered it way back in twenty twelve, long before I had a podcast and I've been taking it every day since. AG one is, to my knowledge, the highest quality and most comprehensive of the foundational nutritional supplements on the market It combines vitamins, minerals, prebiotics, probiotics, and adaptogens into a single scoop that's easy to drink and tastes great. It's designed to support things like gut health, immune health, and overall energy And it does so by helping to fill any gaps that you might have in your daily nutrition And of course, we should all eat high quality whole foods, but most of us are probably not getting enough prebiotics, vitamins, and minerals. and AG one ensures that those gaps are filled. If you'd like to try AG one, you can go to drinkagG one d. com slash Hubberman to get a special offer. For limited time, AG one is giving away a weak supply of AGZ, which is their sleep supplement and a free bottle of vitamin D three K two with your subscription. AGZ is something that I help design. It tastes great, and it's the only sleep supplement I take. It has a collection of different things in it that has dramatically improved my sleep, both my slow wave deep sleep and my rapid eye movement sleep. and I absolutely love it. Again, that's drinkagG one. com slash Hubberman to get a weak supply of AGZ and a bottle of D three K two with your subscription I get a lot of questions about stutter What can people with stutter do if they'd like to relieve their stutter Stutter is a condition where The words can't come out fluently. So you have all the ideas, you've got the language intact, remember, we talked about this distinction between language and speech Stuttering is a problem of speech, right? So the ideas The meanings, the grammar, it's all there. people stutter, but they can't get the words out fluently. So that's a speech. condition and in particular, it's a condition that affects articulation, specifically about controlling production of words in this really coordinated kind of movements that have to happen in the vocal track to produce fluent speech And stuttering is a condition where people have a predisposition to it. so there's An aspect of stuttering You are a stutereter or you're not a stuterer. But people who stutter don't stutter all the time either. So you could be a stutter whose stutters at someimes, but not others And Really the main link between suuttering anxiety is that Anxiety can Prooke it and make it worse. That's Certainly true but it's not necessarily caused by Anxiety can Eent you trigger it. or make it worse But it's not the cause of it, per se So the cause of it is still really not clear, but it does have to do with these kind of brain functions that we've been talking about earlier which is that In order to produce normal fluent speech We're not even conscious of what is going on in our mouths. in our larynx. We're not conscious. and if we were we would not be able to speak because it's too complex It's too precise It's something that we have really developed the abilities to do and we do it naturally, right? It's part of our programming and part of what we learn inherently and you know, it's just through exposure So Stuttering is essentially a breakdown. at certain times in that machinery being able to work in a really coordinated way You can think about know the operations of these areas that are controlling the vocal tract Let's say speech is like a symphony in order for it to come out normally, you've got to have notot just one part, the larynx the lips, the jaw, they can't be doing their own thing. They have to be Ver, very precisely activated very, very precisely controlled in a way to actually create words And so in stuttering, there's a breakdown of that coordination. If somebody has a stutter, is it better to address that early in life when there's still neuroplasticity is very robust. And if so, what's the typical route for treatment? I have to imagine it's not brain surgery typically. I'm guessing there are speech therapists that people can talk to and and they can help them work out where they're getting stuck in the relationship to anxiety. Yeah, exactly. I mean, part of it is about that anxiety, but a lot of it really has to do with u therapy to sort of like work through and think of tricks basically sometimes to create conditions where you can actually get the words to come out a lot of Some forms of stuttering are really initiation problems. Just getting started itself is very hard. You want it start with initial vowel or consonant, but it won't. emmit. So a lot of the therapy is really just focusing on like how do you ree the conditions, you know, for that to happen. There's another aspect to it that I find very interesting is that the feedback, essentially, what we hear Ourselves say, for example. Every time that I say a word, I'm also hearing what I'm saying. So that's what we call auditory feedback That turns out to be very important. and sometimes when you change that, you can actually change the amount someone stutters for better or for worse. It's giving us a clue that The brain is not just focused on sending the commands out, but it's also possibly interacting with a part that is hearing the sounds And there's something might be going on in that connection that that breaks down when stuttering occurs. So There are individuals that are stuterers, but they don't stutter all the time In those instances, there's something happening in those particular moments where this very, very precise coordination needs to happen. in the bra in order to get the words out fluently Eddy, I have to say from the first time we became friends, thirty eight years ago. Something like that something like that. To be sitting here with you today for me is an absolute Its real, not just because we've been friends for that long or that we got reacquainted through the literally the halls of medicine and science, but because I really do see what you're doing as really representing that absolute cutting edge of of exploration and application. I mean, the story of Poncho is but one of your many patients that that' drive tremendous benefit from your work. And now as a chair of a department, you of course work alongside individuals who are also doing incredible work in the spinal cord, et cetera So on behalf of myself and everyone listening, I just really want to thank you for Joining us today to share this information, but also just for the work you do. It's truly spectacular so much. Thanks.