That Neuroscience Guy - Neuroscience Myth Busting Part 2

Episode Date: October 25, 2023

Do we really "rewire" our brains? Does studying animals help us understand the human brain? In today's episode of That Neuroscience Guy, we discuss more common neuroscience myths. 

Hi, my name is Olaf Kregolsen, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. Well, we had so much feedback about the neuroscience myths and so many requests and so many others sort of like, what about this? And what about this? We're going to do another episode. So a second episode on neuroscience myths and what's wrong with them. Well, one that came in pretty quickly was someone asked about the concept of rewiring

your brain. And this is a phrase that you actually hear quite a bit about. And the general idea is that if some part of your brain isn't doing what it's supposed to do, there might be some rewiring that occurs. Now, let's pull this apart a bit more. When we learn, we don't grow new neurons, all right? What we do is we form new neural connections. So if you're learning something new, it's just new connections are occurring, but the actual total number of neurons isn't changing. Now, there's a little bit of evidence that suggests in some parts of the brain, new neurons can grow. But for the vast amount of learning that occurs or neural plasticity, what's happening is new connections and not new neurons being made. and not new neurons being made.

Now, if you take this one a step further, I've heard, and there's popular books on this, that if someone becomes blind, what happens with their visual cortex? And there are some really cool studies that show that you get activity in the visual cortex of blind people, and it's in response to other things. So that is true, and it does happen,

but it's not a massive reorganization and it's not a massive rewiring to stick with that phrase. And the third place I was thinking where you hear this coming up is, you know, what about experts? So for instance, there's some classic studies that show that people spend their life playing the piano have larger hand representations in the brain. Now that is actually true. What happens is more neurons in that region become attuned to using the hands and there is rewiring there or new connections, but you can't just get more neurons everywhere. So those people are also going to lose a little bit somewhere else. Now, the reality is, for instance, the hand region is near the shoulder region, and we don't need a lot of neurons to control our shoulders. So a common space or a common region that would give

them up is something like the shoulder, because it's a pretty large, gross muscle, and you only need to do certain things with it. So there's rewiring your brain. What in reality you're doing is forming new connections. There are those few instances I mentioned. So I'd call it not so much a myth as just using the language a little bit incorrectly. This was an interesting one from one of you. Simple animals aren't useful in understanding the human brain. So studying simple animals, and you might be talking about research in rats or mice, and that's yes and no. We've actually gained a lot of understanding from studies in rats, for instance, about certain behaviors like classical conditioning. So classical conditioning is Pavlov, right? You ring a bell and something happens and the animal learns that the bell predicts, you know, typically it's food, a release of food. And we've learned a lot about classical

conditioning from studying animals. So there is a lot of good research there. And in fact, some of the more fascinating studies in memory by Eric Kandel looked at a sea slug effectively, and that's because there's only a limited number of neurons in the sea slug. So they were able to map out its entire central nervous system, which is kind of cool. Now, with all of that said, animal brains, especially simple animals, and I'm not sure what that means exactly, but I went straight to rats with it. I think you get the idea. The brain is different, right? You know, it's not like an animal just has a smaller version of the human brain. Their brains are fundamentally different. And I think we'll probably end up doing an episode just on that one.

So in some cases, you can't equate the two as well. So again, with this myth, it's a little bit of both. Here's another one. Cortisol is a stress hormone and serotonin is a happiness hormone. Well, basically these neurotransmitters are released in these situations, but the reality is that hormones don't have one specific purpose. It's not the way they really work. So the release of cortisol is associated with stress, but cortisol also does positive things in the brain as well. And the same with serotonin. Serotonin tends to be released when we're happy, but it gets released in other situations. So you can't really think of neurotransmitters like that

in isolation. You have to realize that neurotransmitters work together with neurons firing in the brain and stress or happiness is a combination of all of that, and not just simply the release of a single hormone. Okay, another one that came in that I found interesting. Your eyes see, your ears hear, and your skin feels. Well, that's actually true, of course, but what happens is when you experience sensations your brain's actually also constructing what's happening so it's pulling information from a whole bunch of senses so with your eyes for instance you do use auditory or sound information to figure out what's going on all right right. When you hear something, you might rely

on your memory and previous experiences. So our sensory systems are not that simple. All right. And they're actually doing this construction to try to draw meaning from what's going on. So our brain sort of creates the world we experience. And what I used the other day in class was, you know, we all see the color red a bit differently. And that's one way to think about it is what we do. Our brains perceive certain things completely differently than other people, or at least off by a little bit. And it's very hard to describe because it's just the way you see or experience the world. Another one that's kind of related that I liked,

and the comment was your brain reacts to events in the world. Well, that is true, but your brain also spends a fair bit of time doing prediction. So we don't just wander through the world reacting to what's happening. We do, the majority of our time, we're actually trying to predict and anticipate things. So even for something simple like going for a walk, if you go for a walk, you know, your brain, your feet aren't just reacting to the ground. Your brain is making some predictions about what's going to happen next based on other sensory information. So the information coming in from your eyes, your ears, everything, and your past experience. Again,

your brain is constantly doing this predictive thing where it's trying to predict what's happening next. All right. And it does a pretty good job of that. Most of the time, we're able to anticipate things. An example I like to use here is you can think about driving home from work. When you drive home from work, most of us don't remember the drive, or at least we don't have a vivid memory of it, but you still manage to navigate that whole situation. And you're not just reacting to the world, but your brain is trying to figure out what's going on okay that car is moving at that speed it's probably going to keep moving

at that speed and i'm going to use that to help me develop my experience and how i interact with the world okay this one i have to admit this one made me laugh uh the comment was have you ever heard that your smoldering passions lie deep in ancient parts of your brain, which you supposedly inherited from prehistoric reptiles or that your rational brain, which sits atop your lizard brain tries to cage your desires to keep them in check? No, no, no, and no. Um, If you buy into evolutionary theory, lizards are quite a long way back and our closest, you know, near ancestors are primates. Now, I will unpack this a little bit. You know, our emotional system tends to be a little bit more towards the middle of the brain. So the amygdala, the insular cortex. And there's no doubt that the prefrontal cortex is our analytical brain, which is more on the outside.

But it's not a lizard brain in the middle. It's a human brain. And these two things work together. And the other thing to realize is I know in this podcast I've talked a lot about the amygdala and the amygdala and emotions, and it comes up over and over and over again, but emotions are far more complex than that. And we did an episode on emotions and emotional responses. Emotions are also a cognitive experience, right? So you're the prefrontal cortex plays a role in emotions because your brain has to interpret what it's sensing. So no, you don't have a lizard brain and you don't have this rational brain that sits on top. Sorry to pull that one apart. And the last one I've got for you

today is about mirror neurons, which we've talked about in the past. And the comment was that mirror neurons are special cells that create empathy. Now, mirror neurons are a thing. There are definitely neurons in the brain that are sensitive to what we observe in the world. But there's also a lot of debate about mirror neurons. There is a sort of a proposal that this is how you simulate or you experience what others are doing. But again, it's more complicated than that. It's not just this group of mirror neurons that do this. Your brain is trying to understand the world, right? So your predictive system that I talked about earlier is trying to make predictions about what's going on.

Your prefrontal cortex is trying to, you know, sort through previous memories. And all of this is working together to create empathy and anything else like that. Anyway, that's all I've got on neuroscience myths part two. Thanks for all the feedback. Of course, you can reach out to me on X at that neuroscience guy, which used to be Twitter.

We have our email address, thatneuroscienceguy at gmail.com. I will tell you, we read the stuff that comes in. We just can't always respond because we do get a lot of it, but we love all the ideas. In this episode, you gave us some zingers. This one, the lizard brain is going to be hard for me to forget. I'm not going to lie. And of course, the website, thatneuroscienceguy.com, links to Etsy, where we have our t-shirts that we've never updated because we just don't have the time. But we also have Patreon, where you can support the podcast. And by supporting the podcast, you're really just supporting Matt, who does the sound production. But as a graduate student, he doesn't live off a lot of money.

So the people that are supporting through Patreon, we really appreciate it. And it means a lot and helps keep us going. And of course, last but not least, thank you so much for subscribing and listening. You know, we started this over two and a half years ago, I guess, and we're in a place that we never thought we'd get to. So thank you. Thank you. And thank you again. My name is Olof Krogolsan and I'm that neuroscience guy. I'll see you soon for another neuroscience bite.