Theodore Schwartz on Neurosurgery, Consciousness, and Brain-Computer Interfaces

Hello everyone, this is Jeff, one of the producers of Conversations with Tyler. I'm excited to let you know about a special live show we've just announced. On July 22nd, Tyler will be joined by David Brooks for a live taping of the podcast at the 92nd Street Y in Manhattan. Tickets are available to purchase right now at 92ny.org. This will actually be David's second time joining Tyler. We're thrilled to welcome him back. And we haven't done a live conversation with Tyler in a couple years, so this is a rare chance to see the podcast recorded in person. So don't miss your opportunity to be in the room for what's sure to be a fascinating conversation. In fact, Tyler's already shared with me some of his ChatGPT-informed prep. So again, tickets are available right now at 92ny.org. I expect them to go quickly, so go grab your tickets now. Hope to see you all there. Conversations with Tyler is produced by the Mercatus Center at George Mason University, bridging the gap between academic ideas and real-world problems. Learn more at mercatus.org. For a full transcript of every conversation enhanced with helpful links, visit conversationswithtyler.com. Hello everyone, and welcome back to Conversations with Tyler. Today I'm delighted to be chatting with Theodore H. Schwartz. I saw his book in a Barnes Noble. I bought it. I read it. I loved it. It is called Gray Matters: A Biography of Brain Surgery. But more generally, Theodore Schwartz is professor at Cornell Medical Center at New York Presbyterian Hospital. He has written over 500 articles on neurosurgery and related topics. And he runs a science lab devoted to epilepsy research. Theodore, welcome.

Tyler, thanks for having me. It's really a pleasure to be here.

Now, the medical education process for a neurosurgeon, there's 4 years of undergraduate, right? 8 years of medical school, and then how many years to be a neurosurgeon?

So med school is actually 4 years for everybody. It's universal. And then neurosurgical training is anywhere from 6 to 8 years. The average is usually 7 years. You do 1 year of internship, and then I did 2 years of a junior residency. You often do research, could be 1 and 2 years folded into your residency training, and then you would do additional 2 more years of senior and chief residency. So I was not done with my training till I was 33 years old.

So it could be as much as 16 years for a person.

Yeah, it's a long road.

Is there a way to condense or shorten that? So say you skip undergraduate education or most of it, a person starts at age 21. They finish by age 26. I found most of what can be taught can be taught in 5 years. Is that not true?

You know, I do agree with you. I think that the undergraduate education, a liberal arts— I was a philosophy and English major, right, which was wonderful. And I loved the expanding, you know, universe that I explored. But to be a neurosurgeon, I did not need to read Nietzsche and Kierkegaard. And even in medical school, there's a lot of things that are done that could be condensed. We rotate through the hospital. For 2 years choosing what we want to do, and if you know what you want to do, you could condense it. So I do think that undergraduate education and medical school could probably be condensed into 6 years instead of 8, but I'm not sure that the neurosurgery training— that could be condensed as well. Obviously, you don't have to do research, right? If you're not interested in research, you don't need to do it. You probably could learn how to be a neurosurgeon in 4 years, but if you think about you being on the table, right, rolling into a hospital and looking up at the person who's about to open your brain and, and take care of your most precious possession, you want them to have a little bit of experience. You want them to have some age and some wisdom when they're taking care of you. And if we condense everything, then that person could be 26, 27 years old. So I think we have to balance education with the wisdom that's required to be a great neurosurgeon.

But as you say in your book, the neurosurgeons with less than 5 years' experience, on average, they're not as good. So if we shorten the earlier process, you'll end up with many more neurosurgeons who have, say, 11 years of experience. And if someone tells me, "Well, your surgeon, you know, he raced through everything in 6 years, but he has 13 years' experience doing this operation, and here's his track record," I'm going to be just delighted. I'm not going to say I want someone who went through 16 years, some of which was hoop jumping, and he has only 4 years of doing this operation.

Yeah, I don't disagree with you. So again, I'm not arguing with the training part. I think we could do it much more quickly for sure. But as I mentioned, you know, there's a certain amount of maturity involved in making decisions that we make that plays in. It's not just years that you've been doing it, but it's also wisdom, and wisdom comes with age as it does with experience.

As you know, for ordinary medical diagnosis, and I do mean ordinary, even GPT-4 does slightly better than human doctors on average. Are there parts of neurosurgery, and I don't mean moving around your hand and making decisions on the spot, but where you think AI models soon will just do better than the humans?

I think that in the interpretation of MRI scans, in a patient comes into your office with conglomerate of symptoms and you got to figure out what they have. Those things in AI are very good at. But often, you know, neurosurgery is different than internal medicine. We're usually not presented with diagnostic dilemmas or radiographic dilemmas. The dilemmas that we face are decision-making, physical decision-making in the operating room. That's really what neurosurgery is all about. Remember, a patient will come to us, they already have an MRI scan in their hand, right? So they're coming on and they're saying, I know I have a tumor, I know where it's located, what should I do about it? And the other thing that's tricky about having an AI make a decision, let's say you have a, a tumor that could be observed, it could be radiated, it could be operated upon. So you have 3 options, but what's gonna factor into whether to do the surgery or not is how good the surgeon that you're seeing is at doing that surgery. And not all surgeons are created equal. So the AI will not necessarily be able to take into account the skill level of the particular surgeon that you're seeing, because that's unique to that one surgeon and that one surgeon alone.

But we could measure that, right, if the surgeons would allow it?

In theory, you could measure their outcomes and have them, you know, enter their outcomes into a database for every surgery that they do. Right now, we are so far from doing that, we have no idea what goes on once that OR door is closed and a surgeon is on their own. There's really nobody looking over their shoulder for the most part. So yes, I think that data could be accumulated, but we're not even close to accumulating any of that right now.

But why isn't there some institution, private sector, governmental, that insists that data be collected and processed? That would be very valuable.

Yeah, what's interesting is what's collected now and tracked by hospitals is what they care about. And what you learn when you're in the practice of medicine is that the priorities of a hospital and the priorities of an individual physician are not completely aligned. They're partially aligned. So, for example, one of the things that we measure now that hospitals are very concerned with is whether your patient comes back into the hospital after a certain period of time and whether they get an infection or not. Atul Gawande, you mentioned before, and his checklist. His checklist is, is wonderful, for reducing infections, you know, and, and certain frequent complications. But when I'm in the operating room, I'm concerned about whether I'm going to be able to get this whole tumor out or not. I'm concerned about whether my patient is going to be able to see when they wake up after surgery, whether they're going to be able to walk when they wake up after surgery. And often there's a push-pull decision-making, a Sophie's Choice of saying, should I leave some tumor behind to make sure that the patient can walk after surgery, or should I be more aggressive and try to take it out and try to cure them? And put them at risk of some sort of a postoperative deficit. None of that is tracked by hospitals. Hospitals are not really concerned with whether you get the whole tumor out or not. They're concerned with whether you get an infection or not, whether you get a clot in your leg or not. There's certain very specific things that they track because that's how the government judges them and determines their reimbursement. And so unfortunately, the things we measure, the things that are easier to measure and the things that the government wants us to measure, but they're not necessarily the most important things to be measured in a neurosurgical operation. And the same would be true of cardiac surgery or urology, I presume.

So let's say I need a neurosurgeon and assume also I can't contact you. I have a decent income, but not so much money that I can just buy the best talent in the world. How should I actually make that choice?

Well, the economics of medicine are quite different than other things because most doctors will take most insurance plans. So if you have private insurance, whether it's United Blue Cross or Aetna, you can see an incredibly good neurosurgeon who is likely to take your insurance. There are some pockets of places in the country where some physicians may not take insurance plans, but for the most part, most of them do because the insurance companies have such powerful control over the patients and the patient volume. But if you think about it, and I know economics is really what you are all about, if you think about it, it's somewhat unfair to the physician because the insurance company fixes the rate that they'll pay a surgeon. So if I am day one out of my neurosurgery training and I take out a brain tumor and you have UnitedHealthcare, whatever your insurance is, I'll get paid X dollars. If I'm 30 years older and I have 30 years more of experience and I take UnitedHealthcare and you come to me 30 years later and you're gonna get a much better product, I get paid exactly the same amount as the resident who is the first day outta their training. There is no accounting for experience and expertise in reimbursement for physicians for what they do. I may have a bigger volume, right? So I may do more cases because more patients come to me because I have more experience and more of a reputation. But for every widget I produce, I get paid exactly the same. And the quality of the product can be dramatically different.

But how do I find someone, say, as good as you? Do I call up Harvard or what do I actually do concretely? I Google who's the best neurosurgeon?

Unfortunately, I've tried that and you get some oddball answers. Some of them are correct. Some of them are incorrect. I think the best thing to do is try to find someone that you know, a friend of yours who's in the healthcare profession, and have them call around and ask their friends because they'll know someone who is a neurosurgeon. And it's really— neurosurgeons know who are the top neurosurgeons doing a particular operation because those are the people who write the most articles, give the most lectures, do the most volume. They're people that are known to be very, very good. It can be very hard for a consumer to know that. And what I found is most consumers are so awed by the fact that you are a brain surgeon, you know, that you've gone through this training, that they sort of take what most surgeons tell them at face value. I happen to practice in New York City where everyone gets second, third, fourth opinions. So, you know, people are a little more critical about their physicians and do more research. But I think it is very important to get second, third opinions and speak to people in the medical profession.

I know what economists are like, so I'd be very worried no matter what my algorithm was for selecting someone.

Yeah.

Now, say the people who've only been doing operations for 3 years, Should there be like a governmental warning label on them the way we put one on cigarettes? Dangerous for your health? And if so, how is it they ever learn?

You raise a great point, and I've thought about this. I talk about this quite a bit. The general public, when they come to see me, for example, I'm at a training hospital and I practiced most of my career where I was training residents, and they'll come in to see me and they'll say, you know, I want to make sure that you're doing my operation. I want to make sure that you're not, you know, You're not letting a resident do the operation. And, you know, we'll have that conversation, and I'll tell them that I'm doing their operation, but that I oversee residents, you know, and I have assistants in the operating room. But at the same time that they don't want the resident touching them in training, we are obliged to produce neurosurgeons who graduate from the residency capable of doing neurosurgery. Well, they want neurosurgeons to graduate fully competent, because on day one, you're out there taking care of people, but yet they don't want those trainees touching them when they're training. And that's obviously an impossible task, to not allow a trainee to do anything, and yet the day they graduate, they're fully competent to practice on their own. And that's one of the difficulties involved in training someone to do neurosurgery, where we really don't have good practice facilities where we can, you know, have them practice on cadavers that are really not the same, or have models that they can use that are really not the same, or simulations just not— are not quite as good. You know, I, I don't— at this point we don't label physicians as early in their training, but I think if you do a little bit of research when you see your surgeon, you know, there's a CV there, right? So it'll say this is when he graduated or she graduated from medical school, and you can do the calculation on your own and say, wow, they just graduated from their training 2 years ago, maybe I want someone who has 5 years under their belt or 10 years under their belt. It's not that hard to find that information.

How do you manage all the standing?

When I started out, I had horrible back pain standing in the operating room. Excruciating. I couldn't stand for more than half an hour and my low back would go into spasm. And I realized very early on that neurosurgery is, is a physical activity. You know, you not only have to stand for long periods of time, you know, you can't have a significant tremor. You know, you have to be able to focus for long periods of time, and you have to be able to work on very little sleep because sometimes you're getting woken up at 2 in the morning to do emergency surgeries, and then you have to go back in the next morning and keep operating. What helped me in the end was learning how to do a lot of core exercises that strengthen your core—planks and things like that—and then just practice and experience. Like anything, the more you do it, the more you strengthen those muscles and the better you can tolerate it. But for many years, I had excruciating back pain, and I was constantly stretching in the operating room. And I think a lot of surgeons go through that until those particular muscles that they need are strengthened.

Let's say we put you in charge of the process selecting who gets trained to become a neurosurgeon. How would you improve what we do now?

You know, we choose at the top programs surgeons often based on research criteria. A lot of the, the top programs want someone who have worked in labs and proven that they have a research brain and that they're going to contribute to the field. And that is one aspect of neurosurgery for sure. We want people who are going to improve what we do because medicine is constantly evolving and we need to get better. But on the other hand, you know, surgery is very much a tactile, physical sport that requires judgment and coordination and stamina and sacrifice and grit. And some of the best neurosurgeons combine all of those qualities. And we interview the residents for, you know, 20 minutes when they come in, and it's very hard to evaluate them on all of those qualifications, which is why what a lot of students do who want to go into neurosurgery is they'll actually rotate at that program. So they'll show up there and spend a month, and we'll see what they're like. We'll see if they have the stamina. We'll see how they, you know, function at 6 AM and if they're functioning just as well as at 9 PM. And if they're upbeat and they can maintain a positive attitude and positive mood in the face of all of that work, then that's a good sign that they'll do well. But I don't think we fully evaluate our neurosurgery residents as well as we should. I think you're right. We need some more sort of grit, physical stamina assessments that we can apply to them.

How much does IQ matter?

I don't think raw IQ matters that much. You know, the, uh, the end of the book, I quote this, there's an article that came out in the British Medical Journal that looked at the IQs of neurosurgeons, rocket scientists, and average professionals, and essentially found that they were all about the same. And, and I don't think that raw IQ is what makes a great neurosurgeon. You know, it is psychologically very demanding because you are taking care of people at a moment in their lives that is, you know, the most critical, where they're in most of need of help. And they basically hand over to you their most prized possession for 4 hours, 6 hours, and you have to be on your A-game every time you're under the microscope doing neurosurgery. Because, you know, one false move, one damaged blood vessel, one damaged nerve, and that individual that you're taking care of may never walk again, they may never see again, they may never wake up from that operation. And you don't want to take that lightly. It's an enormous responsibility. And so you want to make sure you choose people who are going to be completely dedicated to the task.

Just as you had to learn standing for so many hours in a row, did you have to learn concentration or did it just come to you naturally?

I think I've always been pretty good at concentrating. You know, I think, you know, we do have to take a lot of tests along the way and you have to sit in your room and study and memorize an enormous amount of information. And that takes the ability to sort of sit and focus for long periods of time. I'm also a musician, which I found very helpful because The ability of sitting in a room and practicing an instrument, which I would do for hours and hours and hours if you want to become very proficient at it, is something that lends itself to neurosurgery.

And you play bass, right? Yeah, I play the bass guitar. Classical or jazz or—

So I started on upright and I moved to jazz, sort of R&B, funk fusion, that genre.

And who's your favorite jazz bass player, Ron Carter?

No, I love Ron Carter, but I have to say Jaco Pastorius. He was an electric bass player. I don't know if you're familiar with him.

No, it's very flamboyant. It's wonderful to listen to.

Yeah, yeah. He was the man, for sure. Why do so few women go into neurosurgery?

This surprised me when I learned it from your book.

So the numbers are going up. Women are actually doing better. They're now at maybe 10%. I think we expect them to be at about 30% in a few years. But it's a very demanding career. And as you know, women often are focused on childbirth and having the freedom to raise their children in the way they want to raise them. Neurosurgery doesn't always allow a woman to do that, but if depending on how you want to, you know, run your life and what you want to do, obviously, you know, I know many women who are neurosurgeons and have children, and they're wonderful mothers to their children. They may not have, you know, 4 or 5 children. They may have 1 or 2 children just to have the time. But I think that is a limitation, you know, to know that you're not going to be there as much as you may want to be for your children.

Why do so many neurosurgeons get divorced?

I think it's the same thing, you know, when you have a career where not only are you out of the house for a long time and you get called out of the house at awkward times, so that could be on Valentine's Day, right? That could be at 2 in the morning. But even when you're there, even when you're at home, there's part of you that's always absent. You know, one thing that I realized is no matter where I am, there's always part of me that's thinking about the patients that are in the hospital that I operated on last week and how they're doing. And maybe one of them is, you know, struggling a little bit and I have to be aware of that. And I'm thinking about the patients I'm gonna operate on next week and the challenging cases coming up and how those are gonna go. And I'm visualizing them in advance constantly. So the past and the future of what you do is weighing on you all the time so that even when you're present at home, you're not fully present at home. It's just a very demanding career, and it's an unforgiving career. I write about in the book, there's some stories of some famous neurosurgeons like Harvey Cushing or Ghazi Yashargil, who people don't necessarily know all those names, but there's a famous story about Cushing who was really the founding forefather of neurosurgery. In the turn of the century, 1905, he really was the first surgeon to dedicate his career to neurosurgery, which at the beginning of the century had a mortality of about 50%. And at the end of the— his career was down to about 8%. Really remarkable what he had done to make neurosurgery safe. But he went in to operate on a Saturday morning on a patient, and he got the news that his second son, who had just graduated or finished his third year at Yale, was in a car crash and died. He got the news in the morning, and he walked into the operating room, and he did the full operation that he was set to do. And then he went and claimed his son's body when the operation was done. And that just tells you something about what kind of a human being he was, what sort of focus, dedication, self-restraint, and discipline was required of Harvey Cushing to move the field forward the way he did.

But wouldn't a substitute be called for? So if I'm the patient, I would want it arranged in advance that my surgeon, if that happened, they would sub in someone else. Maybe they raised the price to me. Even if some individuals might do it just fine, I would never do that.

Well, think about it. Back when Harvey Cushing was a neurosurgeon, there was no one to sub in for him. There were no neurosurgeons. The field didn't exist. He was the first surgeon to dedicate his life just to neurosurgery. So it wasn't like there were other surgeons that had even remotely the ability. So even Harvey Cushing, with his son's death weighing on him, would have given you a better outcome than any other surgeon of that error. Now, in the modern day, yes, of course, there are, you know, hundreds and hundreds of competent surgeons who could sub in. And yes, a surgeon nowadays should cancel that operation and hand it off to someone else. You can't arrange for that in advance. We don't have the ability to do that. I often think about that, you know, the morning when I see my patient before we go into surgery. Every morning we come in, we see them, and we do consent, and we talk to them. And I can speak for myself, I usually go to bed at 10 o'clock the night before, and I haven't had a bit of alcohol, you know, because I'm— I want to make sure I I perform at my best, but that patient doesn't really know what I've been through. They don't know that there wasn't some horrible tragedy in my life the night before. They don't know that I didn't binge on some— I'm not a drug addict at that moment in time because we don't do drug testing and we don't do any sort of testing for surgeons before they walk into the operating room. I'm not saying that should be done because I think we'd all like our freedoms and not like to be under that kind of scrutiny, but it is ironic. We do give an enormous amount of trust to these individuals without really knowing what's going on in their heads. And I think surgeons are expected also to— we're held to a higher standard, and we should be, right? We're expected to take care of our personal lives in a way that separates it from the work that we do.

Putting yourself aside, I mean, do you think you're a happy group of people overall? How would you assess that?

I think we're as happy as our last operation went, honestly. I think that, yes, if you go to a neurosurgery meeting, people have smiles on their face and they're going out and shaking hands and telling funny stories and enjoying each other's company. But it is a way that we deal with the enormous pressure that we face. Not all surgeons are happy-go-lucky. Some are very cold and mechanical in their personalities, and that can be an advantage, right, to be emotionally isolated from what you're doing so that you can perform at a high level and not think about the significance of what you're doing, but just think about the task that you're doing. So on the whole, yes, we're happy. But the minute you have a complication or a problem, you become very unhappy, and it weighs on you tremendously. And it's something that we deal with and think about all the time— the, the complications we have, the patients that we've unfortunately hurt and not helped, although they're few and far between. You know, if you're a busy neurosurgeon doing complex neurosurgery, that will happen, you know, 1 or 2 times a year, and you carry those patients with you constantly.

Is the brain a relevant bottleneck to living forever? So say longevity science, it somehow pans out. We understand old age is a kind of disease. We get some sort of fix, but we can replace your liver but not your brain, right? Without killing you. Is there a way around that?

Yeah, well, let's hope that AI is, right? Because the brain is just a very complex information processing machine. So the hope is that someday we'll have some sort of inorganic way of reproducing the same connections we have in the brain so that we can, you know, live on more permanently in another form. But certainly the biology, the biological material of the brain is problematic because those cells don't reproduce and they deteriorate, they don't regenerate.

Do you have a view on the Star Trek transporter? So you've studied philosophy. Does it kill you? Would you step into one?

There was that other— what was that magic, the show about the magicians with Hugh Jackman? Do you remember that show? The Prestige, I think it was called. That's right. So Nolan would— He would do this magic act and it would literally kill him every time he did it and he would be revived. I would let Spock go through first, and if Spock told me it was okay, I'd follow behind.

But it's only the Spock copy that says it's okay. Like, we have data from television that says it copies you successfully, but is it really you? Or did we make a good copy of you and you're dead?

Well, I would argue over time we all change, right? So the Tyler Cowen of 5 seconds ago is different than the Tyler Cowen that's sitting here right now. So if you could replicate yourself so that there were 2 Tyler Cowens, I think those 2 people would diverge in who they are because they would be completely different people one second after they became a different person, because their molecules would be on a different path, they'd have different experiences, they'd be in a different location in space. So I think we're constantly changing, so I think I would go in the transporter.

Given that people can live after split-brain events, does this mean we're really two people or more people?

Yeah, so I don't think that the unified self really exists in the way that we think it does. You know, as you mentioned, there's a neurosurgical operation called a corpus callosotomy where we can split the two sides of the brain in half so that they become two independently functioning brains, and that person does not feel like two people. They feel like one self, even though the left side of the brain will make the right hand do one thing and the right side of the brain will make the left side do something else. So both halves of their body are being controlled by different brains. And sometimes they're behaving in opposite ways, but yet the individual still feels like a unified individual. How is that possible, to have two brains and still feel like one self? We can also remove half a brain. We do a surgery called a hemispherectomy where we take out half the brain, and that person doesn't wake up feeling like half a person, right? And we know that all that we are is our brain, you know, that's what creates our self. So I think that there are, you know, hundreds of different modules processing information in the brain, and determining what behaviors we should do and making decisions for us, and then we carry out that behavior. And then there's another part of the brain that basically is a storyteller that tries to make sense of it all after the fact. So I do not think we have free will in the way that most people do. I think that our brains make decisions for us. We carry out those behaviors, and then we write a story that makes it into a logical timeline. That makes us feel as if we were the ones, that there was a self that made that decision, whereas in fact that self didn't really exist.

So what you think is you, in your opinion, is just the storyteller part at best.

At best, yes. It creates a story of a self, just like it creates a story of free will.

And does the storyteller part also not have free will? Because that's my view.

Are you willing to go that far? Yeah, I don't think the storyteller part has free will. I don't think we know where those stories come from. I don't think we know where our ideas come from. I think they just emerge into our consciousness. I can't explain consciousness. I can't explain why it's something— it's like to be Tyler Cowen and it's like something different to be Ted Schwartz. I have no idea why that is. So that's still a mystery.

Deep brain stimulation. People tell me all the time it has great potential. What's your opinion? Is it made up? Is it fraud?

Does it have potential? So, I mean, it not only has potential, but that's what we do right now. So the treatment of Parkinson's disease right now is to put an electrode in the brain, and that will stop your tremor in your hand if you have Parkinson's disease, the tremor. So we use deep brain stimulation for that purpose. We also can reduce seizures. We can treat patients with epilepsy with deep brain stimulation and reduce their seizures. And we're getting to the point where we can start to treat depression and obsessive-compulsive disorder and Tourette's and certain psychological issues with deep brain stimulation. We can alter someone's behavior, someone's desires, feelings, based on deep brain stimulation, because all of our behaviors derive from circuits in the brain that are firing in a particular way. So one great example was a patient who had deep brain stimulation, and when they turned on the stimulator, they started to like a particular type of music, a musician. And when they turned it off, they no longer liked that musician anymore. So those kinds of desires can be created and extinguished with stimulating an electrode in the brain. The truth is really any part of your personality can be altered with an electrode or a number of electrodes placed in the right places and altering the circuitry of your brain appropriately.

Any part of your personality or just there's some that are flexible?

I think any part because all parts of your personality are based on brain circuitry., and once we alter that circuitry, we will alter who you are. Just like when, you know, someone develops Alzheimer's disease and no longer recognizes their children, they become a different human being. They become a different person because their— the brain wiring has changed.

So 30 years from now, would you have a forecast what else we'll be able to do with deep brain stimulation?

Yeah, predicting the future is a tough one.

But you see research in the works, right? You're incredibly well-published, well-read. Things in medical science can take 10 to 20 years anyway.

You must have a sense. Well, I think we'll have a very effective treatment for depression and certain mental diseases, things where it's circuitry that's involved, but the biology is still intact. And then we can also talk about brain-computer interfaces, because I find that to be one of the most exciting forefronts. And I don't know if you— when you said deep brain stimulation, were you also referring to brain-computer interfaces?

Not yet, but I am going to ask you about that.

Fine. I just wanted to make sure you were differentiating. But yeah, I mean, you could imagine disorders. You know, there's another famous case of someone who had a large brain tumor, and as the tumor got bigger, pushing on their frontal lobe, they became very interested in child pornography and couldn't control themselves. And, you know, they were going to go to jail, and they found this huge brain tumor, and they took the tumor out, and those desires went away. And then 5 years later, they came back and they re-imaged the patient's head and the brain tumor had recurred. So that's the frontal lobe. It's the area where you— where we did frontal lobotomies that is very sensitive for behavior. So it's clear that so much of who we are is based on the circuitry of our brain and how well it's functioning. And alterations in those circuits can have profound effects on personality and behavior.

Why do you think it's so hard to find biochemical correlates of depression? If it's just a physical thing?

Well, I think we have some, right? I mean, you know, there are medications that we take that are pretty effective at alleviating depression. The thing about medications and the biochemical part of it is that when you take a medication as a pill, it goes everywhere in your brain, right? And depression is probably only in certain places in your brain. There are only certain frontal lobe circuits that probably mediate the depression. But if you take a drug that alters a neurotransmitter in your brain, as a pill right now, that goes to everywhere in your brain. So it's going to have side effects. It's not going to be selective for just the circuits that are causing the depression. There's a new technique that we have called focused ultrasound, which is a fascinating device where we can focus ultrasound beams through the skull into the brain and open up what's called the blood-brain barrier. So when I take a drug orally, take a pill, put an IV drug in, a lot of those drugs don't get into the brain. Because there's protection, because the brain doesn't want poison or toxins to influence the brain. So not everything gets in. So you could imagine a time in the near future where you take a pill for depression that's very effective, and then you do focused ultrasound, open up the blood-brain barrier only in those circuits, in those anatomic areas that are important for depression, and that drug will only get into those specific areas in very high doses. And that could be a much more effective treatment than what we have now.

GLP-1 drugs seem to have the potential to limit addictive behavior. What do you think we learned from that?

Well, again, I think it says the same thing that I've been saying all along. You speak about addiction, you know, there's another famous story about people who are taking a certain Parkinson's drug and they became compulsive gamblers, right? We know that certain medications that you take, changing the chemistry of your brain, can make you more prone to risky behaviors and gambling., and the same is true of addiction. I think using deep brain stimulation to modify addiction is something that's being tried right now. You know, there are animal models where that's being done fairly effectively.

What do you think of Neuralink as a company, their products, what they do?

Yeah, so I am very interested in brain-computer interfaces. I think that Neuralink has created a very unique and interesting device. There are different ways to to create brain-computer interfaces. They're basically two different classes of devices, and what Neuralink does is it puts electrodes into the brain itself to record from individual neurons. There are other devices out there that put electrodes on the surface of the brain, and we don't know at this time which one is going to be better. They're probably both quite good, but what Musk has done with Neuralink is a great device because the electrodes that he put in are malleable, right? They're not rigid electrodes, So the brain is constantly pulsating and moving, and so the electrodes can move with the brain, which is great. Previously, all electrodes put in the brain would create a dense scar around the electrodes to try to pop them out. Those electrodes don't appear to do that. But I think what's important for the audience to understand about brain-computer interfaces, and Neuralink is just one company among many companies out there that are creating brain-computer interfaces, that in institutions, academic institutions around the world, we've already seen that you can put a brain-computer interface into someone's brain who's paralyzed, and you can have them move a robotic arm. You can have them drive a car. You could have them speak. If you have someone who cannot talk because they can't move their mouth, you can take the language production out of their brain, put it into a computer, and have a robot or a picture of someone's face speaking as that person is thinking what words they want to say. So that technology already exists, and it's just about making it commercially available and making it self-contained so you don't have wires sticking out of your head. And so I think Neuralink's going to be very successful, I really do. What I worry about in the short run is the business plan and the market. Right now there's a limited market for paralyzed people, you know, who have ALS or locked in and need that type of a device, although the market, you know, is bigger. What will be fascinating is if we get to the point where we can do it in a non-invasive way and enhance normal human beings, right? So someday, Tyler, we could be having this podcast and you could have a device in your brain that allows you to communicate with me wirelessly through a computer. That is not unrealistic, and we could have this whole conversation virtually just by thinking about what we want to say to each other.

So speculatively, what's your best guess as to how long it might take until I'm hooked up to GPT-whatever it is by then?

Yeah, I think that making the surgery safe could be 15, 20 years. That could happen.

And do we have a way of getting the electrodes out of there? Would we need to do that, or is it irreversible?

No, you can pull them out. You can pull them out. The risk— it's— so the electrodes that go in the brain, that's one of the risks, right? Because if you have a normal human being, you don't want to put electrodes in the brain and risk damaging the brain. Right now, the Neuralink device puts electrodes in part of the brain that control movement, and these are people that are paralyzed, so they're not using that part of the brain. But there are other brain-computer interfaces that just put the electrodes on the surface of the brain, so they don't damage the brain at all, and that's the kind of thing you can do in a normal human being, and you can get the same information from an electrode on the surface of the brain as you can from electrodes in the brain. And so the issue is you have to open up the skin and the skull and slip them in, and, you know, there are some risks to doing that, but just getting the electrodes on and off the brain without damaging the brain is something we can already do.

Let's say the FDA decides such devices are safe, and at least medically they're effective, say, for people who are paralyzed. Should we have institutions that regulate what people can do with these, or should we just let people choose the enhancements they want? No, I think they have to be regulated.

I mean, right now, you know, all these kinds of studies are— any medical device, right, is regulated. There are the FDA, and we have to do IRBs if we want to study them. But say we know it's safe.

It's past that barrier. And I just show up and say, I'm Tyler, I'm fine, but I want to think like GPT-11, please hook me up. Should I be able to do that the way I might go to a hospital and ask to have my appendix out? Well, that's a different—

so you're talking— I don't like that analogy of the appendix because you need your appendix out for a medical reason, right? As opposed to you just want to be hooked up to ChatGPT.

But you could ask to have your appendix taken out. You say, oh, I'm going to North Korea for a year, the embassy. I want to have it taken out now just in case. People have done this plenty.

Yeah, but there's an indication for it. So no, I think the time will come if it can be completely safe to hook you up to a computer safely. You don't need permission to buy a cell phone, right? Like right now we already have a brain-computer interface, it's a cell phone. It's just that it's very slow. So once it's perfectly safe, then absolutely it will not need to be regulated any more than Facebook and X need to be regulated by the government because of abuse. I mean, those types of things may need to be regulated, what you can do with it, if we feel like it's detrimental to society. But just the fact that you want to buy a cell phone, no one's regulating your ability to buy a cell phone, and it'll be the same thing.

Do you have an opinion on electroconvulsive therapy, you know, shock therapy?

Yeah, so ECT basically is giving someone a seizure. We found out years ago that patients who had depression and then suffered a seizure got much better, their depression got better. So we thought, huh, maybe we can trigger a seizure by essentially putting a cardiac defibrillator on the skull, stimulating the brain, causing a seizure with the patient under anesthesia, then wake them up. And it does work. It makes people better. I wouldn't say it's the most delicate, refined treatment for depression at the moment, and it's only used for very refractory depression, but right now it is one of the best treatments we have for depression. And so I think it should be used, you know, in capable hands and qualified hands. Hopefully we'll have more refine treatments for depression in the future, and we'll look back at ECT and be like, wow, that was crazy. We were doing ECT. We have such a better treatment now.

But the fact that it can work at all, what do you infer about the brain and depression other than determinism?

Well, I think, you know, as we talked about, depression is a mechanical, neurologic, biochemical disorder, or it's the normal of someone, but they don't want that to be their normal. And anything, any feeling, any emotion that you have can be altered based on changing the chemicals and the connections in your brain. And ECT does that. You know, a seizure is a, a wave of neuronal depolarization and chemical release that's very, very powerful in the brain that, that alters the network functioning of your brain.

How is studying and treating epilepsy changed your view of what humans are and human behavior?

Epilepsy is a fascinating disease because it's a disease of the circuitry of the brain and not the anatomy of the brain. A lot of neurological— neurosurgical illnesses in particular, brain tumors, aneurysms, there's an anatomic problem. Often when we operate on epilepsy, we see epilepsy, the brain looks completely normal. It's the circuitry that's abnormal. And some of the symptoms that an epileptic can have are symptoms that mimic human experience. So there are famous cases of, for example, I read about Dostoevsky, who was an epileptic, and he used to experience the presence of God in all of his— when he had a seizure, he was 100% certain that God exists, and he would have a religious experience associated with that seizure. And that's been well described. And, and then when you treat them either with medicine or surgery and you cure them of their epilepsy, their religious experiences go away. And I'm not trying to diminish religious experiences per se, but the fact that you can alter someone's beliefs and their religious experiences by altering the brain tells us a lot about religion and about the human mind and the human brain.

And people who are epileptics, what is that correlated with in terms of personality or temperament or any other features, or is it just evenly randomly distributed?

It's mostly randomly distributed. It doesn't say anything specific about who you're going to be, what kind of a person you're going to be. Unfortunately, you know, there's different types of epilepsy. There are epileptics who the medicines don't really work that well, and epilepsy can be a devastating disease to those people. And if you have it when you're younger and you're developing, your brain may not develop normally. But there's some people who have epilepsy and take medication and have very few seizures, and they have very high IQs and are very highly functional. So it doesn't have to alter your brain or your personality in any particular way, and there are some lucky people who can live with it without any noticeable alterations.

Taking all factors into account, what do you think is the most significant bottleneck limiting progress in brain surgery today?

I think the fact that we have to open up the head with a scalpel and drill to get into the skull. And I think the holy grail for us is to put down the scalpel and to not have to drill through the skull and to be able to deliver energy into the brain without opening up the head. And we can do that now with radiation, with focused radiation, but focused radiation can only do so much. We can do it with focused ultrasound as well. Someday we'll be able to optically, you know, focus light into the brain in certain areas and maybe have an optogenetic things that we give into the brain so that the light alters the circuitry of the brain. We can operate on the brain through the blood vessels, which is great. You can treat an aneurysm literally by sticking a needle into someone's wrist and threading a catheter up into the brain and putting metal coils into an aneurysm, whereas in the past we would have to open up their skin and their skull and open the skull and go around the brain and dissect into the brain and find the aneurysm and put a clip around it. And it would, you know, it was very invasive and would take hours and hours. And now we can do it almost non-invasively with a little needle stick. So I think our biggest problem is that we have the skull in the way.

Are nanobots a realistic hope?

Yeah, I mean, you know, Fantastic Voyage, if you know that old movie where they would shrink the scientist and the ship down into a nanobot size and put them into the blood. Yeah, sure, I think that would be great, but again, you have to get out of the blood vessels, you know, and into the parenchyma of the brain to do things. There are some diseases you can treat from within a blood vessel, but there are other diseases that you can't treat within a blood vessel, so the nanobots have to be able to get out and get back in. John F.

Kennedy, was there one shooter or two? What's your perspective?

I think there was one shooter. You know, there's many controversies about Kennedy. Whether Lee Harvey was motivated by the FBI or the Mafia, I'm not going to weigh in on, but in terms of the bullets, what's fascinating about that controversy is that when JFK rolled into Parkland Memorial Hospital and was examined by neurosurgeon Walter Kemp Clark, He did not find an entrance wound in the back of the head, and the Warren Commission said that Kennedy was shot in the back of the head, and that's where Lee Harvey Oswald was standing. And it was never quite clear why the surgeon examining him didn't find an entrance wound. And one of the things I tried to do with this book is that there's a lot of papers written in the neurosurgical literature that the general public is not aware of. And so 50 years after Kennedy was shot, A guy named Bob Grossman, who was the chairman of neurosurgery down in Houston, wrote an article, and he said, you know what, I was in trauma room 1, and I was standing right next to Kemp Clark when he did his examination, but I was a first year out of my training, and there was an entrance wound, and I felt the entrance wound, and I'm not sure why Kemp Clark left it out of his report, but there definitely was an entrance wound. So there was a second witness who was in the room at that time who corroborated the Warren Commission's report that there was an entrance wound in the back of the head, which then places the single shooter in back, because you have just one entrance wound and an exit wound coming through the parietal lobe.

If you think about medicine as a whole, what do you think is your most nonconformist medical belief, the view that you hold that the other people you respect would think is a little weird or too speculative or maybe just flat out disagree with?

That's a tough one, because I tend to be very scientifically motivated in the opinions that I give. I try to follow the literature. I'm— I tend not to be out on a limb too much, but I will say there was a period of time in my career when I was starting to do minimally invasive neurosurgical procedures. And what that means is instead of doing the procedures that I had learned where you open up the side of the head and take off the skull and pull down the muscle and go around the brain, you know, I was learning and pioneering surgeries where we go in through the nostrils with endoscopes or make little incisions in the eyelid And I think at the time when I was doing those operations, most neurosurgeons thought they were crazy and that they shouldn't be done and that they were unsafe. But it was only because I was doing them at the time and I knew that I could do it and the other surgeons had never seen it done. They had never experienced it. So they didn't realize what could be accomplished. So I think there are some instances where you've experienced something firsthand and other people haven't experienced it and you may hold a belief that's different than them, but Ultimately, science will prevail, right? And ultimately, the burden of proof is on you to show that your new technique is as good or better than the other technique. And I wouldn't expect them to believe me until I was able to prove it by writing, you know, dozens and dozens of articles and having other people who also were doing that surgery so it was reproducible to prove that it was correct. But in general, I tend to follow the science, so I'm not much of a wingnut.

Do you think there are areas of science though where the institutions are so screwed up— that you don't actually trust the product of what is coming out, and there's some kind of systematic bias in the ideas being generated.

Yeah, I mean, I think, yes, there's always going to be politics involved, and we always come to any problem from a unique single perspective, and institutions are going to have their biases. So yes, that is true, but in the long run, the scientific method will figure it out, and there will be one right answer, and that institution, whatever their biases, will be proven wrong in the long run. Now, those people might be dead and won't be able to apologize at that point. But I think—

Yeah, I mean— We're not in the long run now. Like the food pyramid, it used to tell us in essence, eat more carbohydrates. It's not obvious that was the right thing to say. It's probably the wrong thing to have said.

But it was our best guess at that moment in time based on the available evidence, right? And that's all science is. It's our best guess based on the available evidence. And once that evidence changes, then we could all be wrong. I mean, I think the best scientist is the one who says, this is how I do it now, but I could be completely wrong. So just if you can show me better evidence, I will change my mind. But based on what I know now, This is what I'm saying.

And you think the process is that efficient?

Well, again, it takes time, right? I think it's efficient over time. Given enough time, it's that efficient. Given day to day, year to year, no, it's not that efficient.

How do you think about your own production function, so to speak? So you have, what, 500 articles, 200 book chapters, 7 textbooks. One of my readers calculated that's a paper or a chapter every 2 weeks for the last 35 years. Plus all these operations. How is it you do it? What's your secret?

You know, I think you become more efficient at things as you get older because you become better at them. So an operation that would take me 8 hours, you know, 10 years ago takes me 4 hours now and then 3 hours. You also have people who help you, right? So if I'm writing a paper, I have, you know, a resident and I may say, you know, I have an idea for a paper. Why don't you write the paper and send me the rough draft? Here's the data.. And so if I have 6 or 7 of those people who are writing papers for me based on my ideas and giving me a rough draft, and all I have— and then I have to edit it and make sure that the data is correct and help them with the introduction, the discussion, you can be much more efficient because you have people who are helping you. And when you start your career, you don't have those people under you who are helping you. But once you've proven that you can write a lot of papers, then you get contacted by millions of people who say, "Hey, I want to write a paper with you," because they know that you can get it done. And so you say— I say, "Great. I have a great idea. You realize that idea. I will help you write it." And then it allows you to sort of multiply yourself by having people who work with you on what you do.

Do you still play music?

I do. I do. I'm in my office now. I have 3 basses and 2 guitars. And I played with a group of neurosurgeons in a band called the Neurosurgery Jazz Quintet for many years. We played at all our meetings. And I'm playing. I have a friend whose 60th birthday is coming up who's a friend of mine who's a musician, and he asked me to bring my bass guitar, so I'm practicing a little bit for that.

What's the age at which, on average, neurosurgeons begin to decline enough where you wouldn't necessarily want one handling your case?

Yeah, you know, age is, as you can imagine, different with everybody, right? Just like the President of the United States. There's no absolute age that a president is too old, it really has to do with the competence of that individual. But on average, right?

A basketball player on average by age 38 is over the hill, but LeBron is pretty good at 40.

Yeah, I would say somewhere in the early 70s. There are surgeons in their early 70s who are quite good, and everyone— there's going to be a bell-shaped curve, right? You understand that, obviously. And so some people are going to be on the tail end of that curve and operate well later than that, but I would say the middle of that bell-shaped curve is going to be late 60s, early 70s.

Do you think neurosurgeons are a group of people with excess self-confidence? The stakes are so high, it's so nerve-wracking. You had to get through a lot of years of work even to get there.

Yeah, it's funny you mention it. My brother-in-law who works at Goldman Sachs was telling me that he was at some meeting where someone was giving them a lecture about, you know, ego and confidence. And you can imagine Wall Street traders have a lot of ego and confidence. And the conclusion was that neurosurgeons have more ego and confidence than any of the Wall Street traders. But the way I talk about it is you have to, at the same time, have confidence and humility, and you have to combine the two. And it's very difficult to do. But yes, you have to have a certain amount of confidence to tell someone sitting in front of you, "I want you to trust me with the most important thing that you possess, which is your brain and your health." You're going to basically Go to sleep and give it to me for 4 hours and put it under my care, and I'm gonna do some risky stuff, but you need to have that done. And I have to have the confidence to say, I'm the best person to do this, or I'm one of the best people to do this for you. And you have to feel that, right? And you have to earn that. At the same time, when you make a mistake and it doesn't come out the way you want it, and that will inevitably happen to everyone, You have to have the humility to say, what did I do wrong? How can I do it better? You also have to have the honesty to say to your patients, look, I'm going to do my best for you, that I can promise you, but these are the risks and these are the known risks. Because if you're too confident, you get to be arrogant, and if you're arrogant, then you're telling your patients that they're going to do perfect, you're lying to them, and then you don't change, you don't look introspectively when you make mistakes and say, "All right, you know, this wasn't perfect. How am I going to do this better next time?" So I think you have to be confident, but you have to be humble at the same time, and you have to have just that right balance.

And the neurosurgeons who are quite self-confident, do you think that's compartmentalized, or do you think they're generally quite confident in many other spheres of life?

I think that changes person to person. I know some neurosurgeons who are quite talented, and they are humble, sweet. They don't appear to be, you know, arrogant in other aspects of their life, and I know others who are differently. I really think that there's no stereotype for that.

I think the sweet ones in other areas, they're often the most arrogant, right? It's a kind of front. I would more likely suspect them of extreme arrogance than the apparently arrogant individuals.

All right, now you're getting to— you're two steps away. You're double-thinking it. I don't know. It's hard to know.

What has it been in philosophy that's interested you the most? You must still think about philosophical issues. You hold them in your hands every week or more.

I read a lot about philosophy of mind and philosophy of intelligence and consciousness and self and agency. So I'm constantly reading and listening to podcasts of new thinkers about those ideas. I find that fascinating. And it's certainly based on my knowledge of the brain. My father was a Freudian psychoanalyst, so I grew up in a household that was very concerned with you know, the brain and the mind and behavior. And I will often try to carve out, you know, an hour or two a day to try to read, you know, and better myself and think about those types of philosophical ideas.

Circa 2025, what do you think of Freud? Has he become underrated?

Look, I think at the time, the fact that Freud realized that we have an unconscious that is controlling what we do based on what was going on at the time. Some people think just like Copernicus and Darwin, Freud was that revolution that sort of took our own agency and our control of ourselves, the ego, and sort of said, "No, the ego is like this little tiny thing. The unconscious is really what's making all these decisions." And now circa 2025, we realize that the brain is doing an enormous amount of processing that we're not conscious of, And that unconscious processing is exactly what Freud was getting at back in Victorian London, so in Vienna, excuse me. I think he was probably underrated. And I think if you look at Freud from a feminist perspective and you don't like penis envy, or you look at the Oedipal complex and just judge him that way, then sure, there's a lot to criticize. But if you look at his structure of the mind and how he subverted the power of the ego and sort of validated the unconscious, I think he was brilliant.

Before we get to my last question, let me just plug the book again. Gray Matters: A Biography of Brain Surgery, Theodore Schwartz. Love the book. Read it cover to cover very quickly. Congratulations on that. Final question. What will you do next?

So you'll appreciate this. I'm starting a company to make a device It's something I've always wanted to do, and I'm hopeful that it's something that will allow me to touch not just one individual and help one individual, but it'll be a medical device that will help, you know, thousands of people and hundreds of thousands of people. So I'm going to move a little bit in that direction.

Good luck with that.

And Ted, thank you very much. Thank you. Take care. It's been a pleasure.

Thanks for listening to Conversations with Tyler. You can subscribe to the show on Apple Podcasts, Spotify, or your favorite podcast app. If you like this podcast, please consider giving us a rating and leaving a review. This helps other listeners find the show. On Twitter, I'm @TylerCowen and the show is @CowenConvos. Until next time, please keep listening and learning.