Your early experiences literally change the way you think and feel about the world — they even shape what you see and hear. Dr. Chantel Prat, a cognitive neuroscientist and professor at the University of Washington, studies how variations in brain wiring make each of us unique individuals and drive our understanding of each other, and of the world. In this episode, learn which parts of the brain are “experience-expectant” (waiting for input on how to develop), and why trade-offs in the brain are responsible for our personalities, our learning styles, and our values. The answers begin to explain how three pounds of brain develop into what we know as the mind. Phil Stieg: Hello. I’d like to welcome Dr. Chantel Prat, who is a neuroscientist at the University of Washington. Today, we’re here to discuss her first book, “The Neuroscience of You”. Dr. Pratt looks at how and why people think, feel, behave, and learn so differently. It’s all because each of our minds is totally unique. Today, Dr. Pratt will provide some really interesting insights into the neuroscience behind what makes you, you. Chantel, thank you for being here with us today. Chantel Prat: Thank you so much for having me. I’m excited to be here. Phil Stieg: So, let’s start at the beginning. What prompted you to explore the neuroscience of what makes us individuals? Chantel Prat: Well, the first ‘Aha’ moment, funny as it is, I actually started out premed. And I first learned about Phineas Gage, which many people have heard something about. Phineas Gage, sort of legendary individual who suffered an accident that blew a railway spike out the right side of his frontal lobe. He walked away from the incident, but his personality was permanently and fundamentally changed. The brain is an organ that makes you, you, you know. You have lungs that oxygenate the blood, and the heart circulates this oxygen throughout the body. But the brain uses this oxygenated blood to create the energy that drives the thoughts, feelings and behaviors that we identify with as being us. And so the ‘Aha’ moment for me was when you change the brain, you change the individual. And I went about trying to figure out the science behind that. What do we know about variation in brains and how it drives this different way of understanding the world. And I was quite surprised to find out that variation was something that was largely treated like statistical noise. Differences between people were ignored or blurred over. We were very interested in what was the same in everyone. And this surprised me. So, like, stick 20 undergraduates in a research experiment, ignore the things that make them different and only focus on the commonalities and use that to form the theories of how the brain gives rise to the mind. We miss all the interesting nuances that make us us. Phil Stieg: So I think you’ve kind of clarified that the purpose of your book, The “Neuroscience of You,” is to find out who you or who I am. Just as an overview, before we get into it more deeply, can you describe what you think are the key messages that you’ve created throughout the book? Chantel Prat: Yeah, I think one key message is that normal is not a single value. There’s not a single way of being normal. There are many different axes of being that fall within this normal or typical range. And within that space there are a lot of interesting and important tradeoffs. Where you might fall on an axis, might give you a strength in a particular situation and a weakness in another situation but not be objectively better or worse overall. There are all these interesting tradeoffs in the brain, these different ways of being that don’t necessarily scale to better or worse. I think it’s amazing that people don’t understand how their brains make them “them” and by virtue, how different brains that they might be trying to connect or communicate with are understanding the world or processing it in different ways. Phil Stieg: So what accounts then for the differences in the way you might interpret something versus the way I would interpret something? Chantel Prat: Oh my gosh. So many things. So many things. And therein lies the question. Right? I think— Phil Stieg: —That’s the purpose of the book? Chantel Prat: Right, One thing that we are becoming more and more aware of is that our version of the truth is only one version. Yet it’s so easy to assume that the way your brain works or the things that you take out of any situation is the way everyone’s brain works or the things that everyone would take away from any situation. Phil Stieg: One of the take home messages for me in reading through the book is that my perception of the world is not only dependent upon my genetic construct, but more importantly, or at least 50% equally, is how my brain has been trained. Chantel Prat: Exactly. And I think that that’s something we miss. So we’re interested in diversity and people who come from different places, but I don’t think people fully understand how much that influences literally the way you see and perceive the world. By the age of six months, we all start losing the ability to hear sounds that are in languages we’re not exposed to. We can’t hear some of the primary phonetic differences that we’re born being able to hear because we’re not exposed to them. I love to talk about the dress that people couldn’t agree whether it was blue and black or white and gold. That’s color, which many of us understand is related in some way to the properties of light in the world around us. Your own experiences with natural versus artificial lighting will drive whether you’re likely to see the dress as blue and black or white and gold based on whether you assume it’s in a shadow. What you see and what you hear are shaped by your experiences. And think about how that scales up to values and more abstract things. Phil Stieg: Individual brains specialize in different functions. How much of it is nature genetics and how much of it is nurture? Was I born with a different quantity of neurotransmitters in my brain versus yours? Or did I grow up in an environment that nurtured me to do the things that I do well more aptly than the things that you grew up with? And that’s why you do what you do well. Chantel Prat: Right. It’s so complicated because your nature, the way you’re born, will also attract you to different environments. So you might be risk seeking by nature, and that means you might seek out more adventurous opportunities. I think that the best theories about nature and nurture talk about range. You might inherit an opportunity to benefit from different environments and it would then depend on the part of the brain. So some of our brain areas are “experience independent,” things that make your heart beat and your control respiration. You don’t need to learn those things. Some parts of your brain are “experience expectant.” They’re waiting for visual input or auditory input to tune their networks to that thing. This is like your frontal lobe, your parietal cortex. They have no a priori idea about how to be and these are the things that continue to change with your experiences throughout the lifetime. So it kind of depends. Phil Stieg: So I think though, as you said, if you were more of a risk taker versus a risk averse person, we’d be able to look at is your dopamine level higher? Are there more dopamine pools meaning that you’re more risk, more of a risk taker, or are you more of a contemplative, I’m-going-to-sit-back-and-wait, serotonin rich person? Can we test those things and say, Phil, you’re a risk taker and Chantel you’re more of a serotonin person? Chantel Prat: You can. And actually one of my good friends in graduate school, Mike Cohen, did something like this with dopamine communication in the brain and extroversion. For instance, the brains of extroverts respond with about twice as much reward when they are faced with an unexpected surprise, an unexpected good thing. And there are not the same differences when they have an unexpected disappointment. So when your brain gets dopamine, not only is it feeling great, it’s rewiring. Dopamine is a signal for learning. It’s one of the things that drive us through life. We want to feel good and so we learn about the conditions that make us feel good. So imagine being a young child that takes a chance to wander out in the world and you find something, a puppy or whatever it is that makes your brain happy, and get twice as much reward from that. That starts the learning process that rewires. I’m going to choose to go outside again. I might find something exciting. And your brain is twice as excited and so it learns twice as strongly from that. And you can imagine how that drives going out, exploring kinds of behaviors that are associated with extroversion. Phil Stieg: I like the example in the book that you use about the taxi driver versus the bus driver in London. Can you relate that story to us? Chantel Prat: Oh, man, that’s a great nature/nurture question. These taxi drivers in London became famous when neuroscientist Eleanor Maguire found out that they have a bigger part of the hippocampus, which is one of the regions that we know is really important for forming and retrieving long term memories. And for those of you who don’t know, being a taxi driver in London is no slouch job. They have to study for a test called The Knowledge, which involves remembering tens of thousands of maps of the different streets in London, the various landmarks one might want to go to, and only about half of the people who sign up to study for that test pass it after several years of studying. So she started out by looking at the people who had already passed the test and showed that they had bigger areas of the hippocampus that are responsible for remembering spatial locations. And then she asked herself the question, well, this is a nature/nurture question. Are people born with big hippocampi? And then they’re well suited to become a taxi driver? Or is something about the demands of this test and this job changing the shape of their brains? So she recruited a group of people who signed up to take the test and studied their brains over the course of this studying process. First, she found that there was no predictor of who would pass or fail from a brain perspective, so they did not start with bigger hippocampi. After they had studied for their test, the hippocampus, the posterior part of the hippocampus grew. They also noticed that in these experienced cab drivers, there was a corresponding shrinking of the adjacent part of the hippocampus. So as they stuffed their brains full of these spatial maps, the neighboring part of the brain was kind of getting crowded. So to figure out if there was a functional cost to that, she put taxi drivers up against bus drivers in a kind of literal head to head measure of their memory skills. What she found twas that there were costs and benefits associated with this brain design. The cab drivers were better at remembering new spatial information, very good at understanding how far apart two landmarks would be and so forth and so on. But there was a cost to remembering new information, particularly when it was verbal in nature. So lists of words, the bus drivers outperformed the taxi drivers on, for instance. Drawing something new from memory, an object, the bus drivers were better than the taxi drivers at. So this whole taxi driver experiment was really illuminating when it came to how our brains adapt to the jobs that we ask them to do and that there are costs and benefits to it. Phil Stieg: But then there’s also the other thing you allude to is the, quote, “neural cocktail.” Please explain what you mean by neural cocktail and then how you’re different than me in that regard. Or maybe different than me. Chantel Prat: Yeah. So our brains use chemicals to communicate. We need neurons to be able to communicate with one another, but we need to keep track of who is talking to whom. And one of the ways that our brains solve this problem is by having chemical languages, which is our neural cocktail. These are the neurotransmitters that are available to send signals from one neuron to the next. The neurons don’t physically touch one another. They pass a chemical message. And not all neurons speak the same language. That’s one of the ways that we keep track, right? So I might send a Dopamine signal out, but if a neuron that’s next to me doesn’t speak Dopamine, then there’s no concern about interference or cross talk, right? So there are critical differences in the availability of these neural chemicals that affect our way of understanding the world and operating in it. One of the things that we’ve done in the lab, is study what your brain does with dopamine. And these two pathways in particular, which are what we call “carrot learning,” when you receive a dopamine burst that teaches you to enhance the activity, the connection between the action you just took and your estimated reward for it, or “stick learning,” when you learn from disappointment, which feels bad, but is a really powerful learning tool. So stick learning— Phil Stieg: —it’s a motivator? Chantel Prat: Well, it doesn’t motivate you, but it moves you forward. How about that? Phil Stieg: Okay. Chantel Prat: Right? Because learning what is a bad choice is as important, if not more important, than learning what is a good choice. So if you do something and the outcome is disappointing, your brain weakens the connection between the action that you just took and the environment that you were in. Phil Stieg: Thinking as an educator, do we then, like you were just saying, try to create that environment where there is more dopamine, even if it’s a negative environment? The student doesn’t want to be a student. How, as an educator can I try to increase their dopamine levels so they go, “as much as I hate this, it’s still fun. I’m getting some pleasurable response from it.” Chantel Prat: Oh, my gosh. Motivation and understanding how brains work, that’s the key. Because if you think about it, we often not only in education, but in diagnosing patients, we set them up for failure. We do things that we know they’re not all going to be able to do as a way of assessing how they’re doing. And of course, in the process, we’re making them feel bad. Right? Who wants to sit in for a two and a half hour neuropsychological assessment where it’s like you couldn’t name the first picture, but I’m going to have you not name 42 more pictures before I tell you you’re having an aphasia problem, right? It feels bad to fail. We could think about assessment as being good for the people who already know how to already know the material, but being demotivating for those who don’t, right? I think motivation is really critically missing, and I think that strength-based education would be effortful and we would need a lot more teachers and a lot better models of how different people work. But I think that our current education system is really set up for that one size fits all kind of learning, and fourth or fifth grade, you’re expecting to be able to take in all of this material through language. And if that’s not your strength, then you miss not only the reading experience, but social sciences and science and things that you might otherwise excel at if you had been given another way in.
(Interstitial Theme Music) Narrator: Our guest this week, Dr. Chantel Prat, mentioned the story of Phineas Gage as an early motivation for studies of the brain and individuality. We’d like to take a moment to appreciate the significance of this historic tale in the annals of neuroscience. There’s a saying among nuclear physicists; studying the structure of the atom by using a particle accelerator is somewhat like trying to figure out how a fine Swiss watch works by smashing it against the wall and picking up the pieces that fall to the floor. In a sense, the same could be said by neuroscientists. In the centuries before the invention of modern diagnostic tools like functional magnetic resonance imaging, nearly all scientific understanding of how the brain worked came from “picking up the pieces” after traumatic, disfiguring accidents. In 1848 a twenty five year old railroad construction supervisor named Phineas Gage was preparing an explosive charge in a rock ledge. Suddenly the charge went off. A thirteen-pound iron rod rocketed high into the air, passing through his left cheek and out the top of his skull before landing eighty feet away. Miraculously, Phineas survived the accident – but not unscathed. It became apparent to those who knew him that Phineas had undergone a sudden and quite dramatic change in his personality. Before the accident he was described as hard working and well liked by his employer, but afterwards they reported that he had changed: [Mr. Gage] is fitful, irreverent, indulging at times in the grossest profanity … A child in his intellectual capacity and manifestations, he has the animal passions of a strong man. In this regard his mind was radically changed, so decidedly that his friends and acquaintances said he was “no longer Gage.” Nineteenth Century neuroscientists had long debated as to whether the brain had specialized regions for each of its functions, or whether the whole brain was one large, undifferentiated organ – secreting thoughts the same way the liver secrets bile. Phineas’ impulsive behavior and lack of inhibitions appeared only after he suffered physical damage to the frontal cortex. This was evidence of the specialized role of that region in controlling behavior. Making that connection gradually shifted our entire view of the structure of the brain. Phineas became the object of great fascination to both the scientific community and the general public. A year after the accident Professor Henry Jacob Bigelow of Harvard Medical School presented Phineas at his lecture to the prestigious Boston Society for Medical Improvement. Later he was a “distinguished exhibit” at P.T. Barnum’s American Museum in New York City. Thankfully, today’s neuroscientists do not have to rely on freak accidents to help advance knowledge in their field. Nevertheless, the preserved skull of Mr. Phineas Gage – along with the iron rod that had once passed through it – are still on display in the museum of Harvard Medical School as a gruesome reminder of his contribution to our understanding of the brain. (Interstitial Theme Music)Phil Stieg: People would agree that diversity is a good thing, yet most observers would say that we live in a polarized society. Is there an evolutionary reason why people who share a set of beliefs gravitate towards each other. What about the brain makes us do that? Chantel Prat: Oh, that’s so great. So brains of a feather flock together. Social neuroscience is telling us this, right? First, I think if you think about your family group, even our in-groups have quite a bit of variety. And the reason that I think variety exists is because humans are social creatures. We evolve to problem solve in groups. And so in your group it’s advantageous to have people who work in different ways and think and understand the world in different ways and notice different things about the environment. But I think that what you’re getting at is, we’re motivated to understand the people that we consider to be in our in-group. So for instance, your brain gives you a chemical called oxytocin to facilitate relationships that are evolutionarily important, your pair bonding, your parent child relationships. And what oxytocin really does is turn up the reward value of social cues. It makes paying attention to the way other people work rewarding. Because I think understanding someone who works differently is really hard. It’s not that we can’t do it. It’s that it’s really hard. So then when you go out of whatever it is that you consider your in-group, what you find is that people naturally gravitate toward others who work like we do. Because it’s easier. If I’m trying to figure out why somebody’s doing what they’re doing, and I can just imagine why I would be doing that particular thing, it’s much easier for me to understand that person. So I don’t have necessarily the motivation to understand somebody who works differently. That’s not in what I would consider to be my in-group. Phil Stieg: I get it. Even within your in group, there’s a little bit of diversity. But again, looking at society now, it seems like we’ve become extremely marginalized on one side versus the other. And again, looking at it from an evolutionary standpoint, there’s the short term and the long term trade off, right? The short term trade off would be I want to be around people who think like me, live like me, and do like me. Because that requires the least amount of brain energy, least amount of consumption for brain energy versus the long term plan would be that as a society, it is best to have diversity of thought so that we understand all of the consequences, right? So it seems to me like it’s a funny game that our brain is playing on us right now in terms of where we’re going. Chantel Prat: My answer to that would be this, we get closer to the objective truth when we can actually consider other opinions. If you understand that your brain is telling you a subjective truth that it thinks will maximize your success, and given that it’s really energetically demanding to understand someone with a different perspective, the question is, do you want to have a better understanding of the objective truth? Are you trying to understand something bigger than your “lane” and have kind of a better appreciation of some system or something that you’re trying to decide in or make policy about? Then I think the only way to get closer to the objective truth is to bring in other points of view. Doesn’t mean you have to agree with it. And I think the really important thing to know is that you won’t necessarily like it. We feel more affection for people who think like us, right? That’s a part of our identity and the way that we protect our own ways of being. But yet, if what you want is something closer to the objective truth, I think we have to get there. Phil Stieg: So I’ve swallowed the Kool-Aid. I’ve read your book, I understand that my brain is different than your brain. I process things different than you process things. But as you said at the start, the purpose of writing the book was, if we understood that we did do things differently, it’ll increase our understanding of each other. That’s a leap in my mind. What’s the process that you describe for helping me understand you in a fair and equitable way? Chantel Prat: You’re right that it’s a leap because just because you can doesn’t mean you will. Right? That’s about the motivation piece. Sometimes we don’t want to understand people who work differently because our brains are protective of our own identities. Curiosity research, I think, has the answer to this. When you feel curious, the subjective feeling of curiosity is associated with a brain that has already decided that exploring this new information space is safe. I think when we’re in front of new information now, our brains evaluate psychological safety. And if this thing flies in the face of some belief that is identity-based in me, I’m not going to feel curious about it. I’m going to protect my identity and my sense of belonging by saying that is wrong or that’s bad science. Part of what limits our ability to be motivated to connect with someone else is a feeling that we are right and they are wrong. I hope that if I could give you some very scientific, objective ways that different brains understand the world, and also that our different lifetime of experiences shape the way our brains understand the world, you might start by relaxing your belief that you are correct and that if you can do that, you can become curious. I think if we can appreciate that two people can be right for different reasons or their brains can be right for different experiences, it might drive curiosity. And curiosity is dopamine based. It’s a huge motivator if you can get to the place where you say, okay, I don’t have to believe like that person, but I will be better off if I understand why that person is the way they are. Phil Stieg: Dr. Chantel Prat. It’s been the most exciting time sitting here discussing your book “The Neuroscience of You”. I wish you success in your mission to promote curiosity and appreciation for brains that think differently, and help society treasure what makes each of us unique. Chantel Prat: Thank you so much for having me. It’s been a delight.