That Neuroscience Guy - The Neuroscience of Nature versus Nurture

Episode Date: June 24, 2024

Humanity has long debated whether the circumstances of our birth, our Nature, or our development, our Nurture, are more influential on our lives. While this discussion is often discussed through biology or social psychology, what might neuroscience tell us about which is more important? In today's episode of That Neuroscience Guy, we discuss how our genes and experiences influence our brains. 

Hi, my name is Olof 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, today I want to address the age-old question, nature versus nurture. And I'm going to do this obviously in terms of our brains and neuroscience. So on today's podcast, the neuroscience of nature and nurture. So probably the best place to start is what we're born with, like, you know, what's in the brain when we're born. All right. So I've done a podcast on development in the neuroscience of being young, but let's just focus specifically on what the brain knows at birth. Well, basically at birth, only the lower portions of your central nervous

system, so the spinal cord and the brainstem are very well developed. All right. And the brainstem isn't a dumb region, right? There's a lot of things happening in the brainstem as you'll see shortly, but that's reasonably well developed. Whereas the higher regions of the brain, so the cerebral cortex and parts of the limbic system, they're still fairly primitive at birth. Now they do develop quite rapidly, fairly primitive at birth. Now they do develop quite rapidly, but they're still not anywhere near where we would like them to be. So in terms of a newborn baby's behavior then, the lower brain, so the brainstem, it's basically responsible for the grasping, the kicking, the crying, sleeping, rooting behaviors, feeding. And these are functions of the brainstem and the spinal cord.

So the baby's born with the ability to do these things. Moving the limbs is natural. It's a reflex. All right, try to grab onto things. It's something that's a reflex that you seem to be hardwired with. Crying when you're disturbed. So it's not really a product of the developed emotional system. It's just a response at this stage, you know, needing to sleep. That circadian rhythm is in there. And we've talked about circadian rhythms in the past, rooting behaviors, feeding, you know, the baby's

desire, you know, that any parent goes through the phase where the baby will put anything and everything in its mouth this is natural all right they're literally trying to figure out what they can eat and this isn't like a thought process the baby's not going hmm i think i'd like to eat a red piece of lego it's just going grabbing it on reflex almost and sticking it in there because it's trying to feed itself and it knows it needs to um and this is you you know, the sucking response. You know, that starts naturally almost. And there can be a bit of stress,

but generally it kicks in for most people and it's there. Even like visual behaviors, okay, parents are always surprised that a baby will orient to mom or dad's face. But this tracking behavior is basically innate to us. And this is why babies like bright objects, things that stand out or pop. If you hold up like a red ball, a baby will orient to it reasonably quickly as best as it can. Whereas if you hold up a ball that was kind of a dull color that blended in with the background, they might not even see it.

So this visual circuit orientation is also thought to be controlled by the brainstem. So this is a very low level visual response that you're born with. Now, as the baby matures, it's going to orient to mom or dad's face purely out of affection and love. But initially, I hate to break it to you, it's not like they're born and going, that's mom or dad. It's just that visual object stands out. At least that's the neuroscience behind it. And what pediatricians do very early on is they basically test reflexes of the newborn. pediatricians do very early on is they basically test reflexes of the newborn. And the reason they're doing this is to make sure that the lower, you know, these lower brain stem areas,

the spinal cord are properly developed. So if a baby is premature, for instance, these things might not be there yet, right? And that's one of the reasons that, you know, doctors aim to try to get pregnant mothers to a certain time window because we know from, you know, research that if you get to a certain point, then these key reflexes for survival will be there. And preterm babies may not have some of these reflexes, which creates all sorts of problems. And these reflexes that they look at are ones called the doll's eye maneuver. And it's basically if the baby has its head turned to one side, the eyes will stay focused forward.

All right. Which is a bit weird, but that's what babies do. It's the moral or startle response. And basically, if the baby gets startled or surprised, its arms will sort of flail out naturally and then it'll bring them in slowly. And it's basically something that's a response to potentially falling or, like I said, something being startled. And it's just a natural survival kind of instinct. something being startled, and it's just a natural survival kind of instinct. And even the stepping reflex, if you hold a baby up and you basically have their feet on a flat surface, you'll see that they start to try to move. And I talked about this on an earlier episode.

This goes back to the concept of what's called a central pattern generator. A central pattern generator is a neural circuit within the spinal cord. And a lot of people think that this is how walking is governed, this hardwired thing that makes the legs move. And when you look at babies in this sort of stepping response, it's seen as pretty strong support for the central pattern generator so that the baby is actually wired for walking at birth it's just not able to do it because it doesn't have the strength to support itself or the coordination for that matter so the human brain as we know takes time to develop and basically what nature's done is it's built in these things, these neural circuits, breathing, things that help your heartbeat, circulation, sleeping, sucking, and swallowing. They're up and running basically for survival because if those things weren't there, then the baby could potentially die if you think of it from an evolutionary perspective.

Now that's the nature side of things. And there's a little bit more. You could ask the question, from a neuroscience perspective, what's our potential? Now, on the extreme ends, some people's brains are wired differently. And we've talked about a range of neurodiverse issues. But let's just go back to intelligence, for instance. issues. But let's just go back to intelligence. For instance, Einstein's brain was wired a bit differently in the episode when we talked about it. You might recall that there's not a lot of evidence or there's some evidence that it might have been larger than normal, but the key thing is it had more interconnections. And the belief is that Einstein was born that way. So just like there's some people that are seven foot two and there's some people that are seven foot two, and there's

some people that are four foot two, you know, there are these extreme ends where nature gives some people these exceptional brains. But for most of us, it's nurture, all right? Our brain is basically waiting to learn, all right? So as we experienced the world, and I just talked about this when I was talking about the neuroscience of chat GPT, but essentially our brain is just waiting to get wired in a sense. Now, parts of the brain are specialized. Again, this is nature. The sensory motor strip is in the same place for all of us. But there are individual differences in the sense that some of us might have greater hand representations than others, which means it would probably have better sensation

on our hands. And if that was in the motor region, better control of our hands. And this is true for visual parts of the brain. There's a really cool area called the fusiform face area, which is roughly in the same place for all of us and for pretty much everyone that part of the brain learns to recognize faces. Now that's actually tied more to the structure of the neurons in the region as opposed to being hardwired for faces. It just turns out that the visual shape of a face matches well with the neurons that are there. So nature has laid out these regions, but the reality is for a lot of what we learn is nurture. You know, if you want to be intelligent, you know, the evidence is pretty clear that reading from a young age, you know, doing math, doing engaging things,

making your brain work, if you will, will lead to higher intelligence scores. All right. So the brain of someone that's seen as smart, typically, if you look at the background, most of the time, they've done lots of things to give their brain lots of information, which is a basis for intelligence. This is also true for movement skills, whether it's playing a musical instrument or playing tennis.

All right. The more you practice something, the more those neural patterns get stronger and you get better. You know, the example we use here in Victoria, B.C. is Steve Nash. You know, he is known in the NBA as one of the greatest free throw shooters of all time. Well, I personally remember watching Steve Nash shoot countless free throws and the same with his dribbling skills and his passing skills. You know, it's pretty rare you find an Olympic athlete that hasn't put in tons of practice. And what does that do? That develops the sensory neurons and the motor neurons so that you're better at those skills. And this is true

with cortical things as well. You know, one of my claims to fame, and I'm not trying to brag, but I got in the top percentile for the graduate record exam for mathematics when I wrote it. Now, I'm not a math genius. Anyone that's seen me do math knows that's not true. Am I good at it? Yes. But I taught four years of high school math before I wrote the GRE. So for four or five hours a day, I was doing math problems for four years. And then someone gave me a math test and guess what? I was good at math. All right. So our brain is like this as well. Like I said, on the extreme ends, there are some people that are wired a bit differently, but you can become, you know, at the top of a profession or at the top of a skill purely through nurture or hard work. Now, of course, there's things you can do to damage a

brain in utero. Fetal alcohol syndrome is a great example. So if you are pregnant, you have to be really careful to avoid things that impact kids. Drinking is a big one. So if you are pregnant, you have to be really careful to avoid things that impact kids. Drinking is a big one. Just forget the glass of wine a day to relax, take a break, and anything else that damages you will damage the kid because the kid is literally attached to you. So you can have a negative impact on the brain before birth. I was curious, so I did a bit of digging and a bit of reading because I was curious about the positive side. And what I've learned is that while there's a lot of anecdotal evidence

that suggests reading to an unborn child helps their brain develop, the science there is really not there. There's a lot of articles in popular magazines. There's a lot of blogs and stuff. But there's very few scientific papers that show that impact. But what is shown is that reading to a baby does have a positive impact on the mother because it helps promote the bond with the child. Now, of course you love your child, but these activities where you engage with your child more strengthen that bond further. And if the mother is in a

positive and good state, that will impact the child to some extent. So there is some impact that the positive things you can do are there. And that includes exercising, of course, getting sleep, eating as healthy as you can, all the things your doctor would tell you. Anyway, that's a bit on the neuroscience of nature and nurture. To summarize, you're born with certain reflexes that are necessary for survival, but pretty much everything else is something you learn as you experience life. Don't forget to check out the website, thatneuroscienceguide.com, links to Patreon where you can support us.

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