Speaker 1: 0:00

Welcome everybody. This week, we're going to be talking about the next step in our understanding of how our kids' brains develop. Last week, we talked about stressors and how they impact children during pregnancy. This week, we're going to start talking about our children's brain and emotional development, from birth until the period of two years. So there are really just two main points that I want you to take away from today. The first is that it is your genetics and your experiences that build your brain together. This harkens back to the diathesis stress model that we talked about previously in the video about the effects of stress on children while they're in the womb. The second thing that I want you to learn from today is that toxic stress affects your child's brain architecture. Those two things go together. Stress affects your child's brain architecture. Those two things go together. So, one, your child's brain is developed by a combination of their genetics and their experiences, and two, toxic stress affects your child's brain architecture.

Speaker 1: 0:56

Big takeaways. So let's start for a second thinking about how your child's brain develops in the first place. And it builds on itself. That brain structure starts at the back of your child's brain, right the back of that brainstem, which is the more primitive portion of the brain and it curls up and over to the front of the brain where the more executive functioning takes place. So it builds on itself. While your child is very young, right An infant up to two years old they're simply starting to get the basics in place and their prefrontal cortex is not yet fully developed. I mean, that's not going to occur. Children don't reach their full adult mental capacity until they're 25. And that's why you can't rent a car until you're 25. So this is a very long process.

Speaker 1: 1:47

One of the things that we have to keep in mind when we're talking about how our child's brains develop is that humans are altricial. That means that when human babies are born, they're essentially helpless, right? It's kind of like when a baby bird is being born or when a rodent is being born, like when rodents are being born. They're deaf and they're blind. They rely on smell. When human babies are born, as you know, they rely on their parents for everything, and humans are kind of unique among altruistial species anyway, because it takes so long.

Speaker 1: 2:18

The glide path of a human from infant to adulthood is very, very long. We just talked about the fact that your prefrontal cortex isn't fully online. Your executive functioning isn't fully online until you're in your early twenties. So what is the evolutionary benefit of that? Because it puts an infinite risk. An infant human has to rely on their caregiver to provide everything to provide safety, to provide food, to provide shelter all of the things that a creature needs to survive. And also, if you think about it, not every parent is a great parent, I think, as we know, unfortunately. So human effort is kind of playing the lottery in terms of having a parent who is capable or interested in providing for them.

Speaker 1: 3:02

So what's the evolutionary benefit to being not only altricial but also over such a long period of time? Well, one hypothesis about why this is the case is that, by having this long glide path, it enables our brains to sort of take its time and develop really complicated structures. It enables us to have a really complex brain development that permits us levels of thinking that other species don't have Some evidence for. That is the amazing plasticity that our brains have during childhood. Your child's brain is extremely plastic, is moldable, is able to learn to build new pathways, to prune away unnecessary pathways, unnecessary pathways, and so, in the right hands, in the right caregiver's hands, this permits a child to spend a great period of time, with a very plastic brain that permits them to learn complicated things right, to have the ability to have complex emotional regulation, complex intellectual activities. If we put all that together, assuming that there's a good caregiver, then it's an amazing outcome. And not to mention the fact that, if we're thinking evolutionarily, it's a lot of work for the progenitor as well. For the parent it's a lot of work to have a child who is altruical, to have a child who depends on you for everything for up to 20 years or so, to have a child who depends on you for everything for up to 20 years or so. So the only real reason why that is the case is because the product at the end of that 20-year process is kind of amazing. Right, it's the human being, fully formed and well-formed, which is fantastic.

Speaker 1: 4:37

The downside of that is that all powerful experiences shape our brain's architecture, shapes our emotional regulation, shapes our ability to have social interactions. So if you have powerful negative inputs, that's going to affect your brain architecture negatively, because our brains develop from the base up. They're not all developing at the same time. Some portions of the brain have rapid bits of growth, while others are kind of maintaining Some portions of the brain have rapid bits of growth, while others are kind of maintaining. One way to describe these different times, when the brain is either progressing rapidly or is kind of on hold, is saying that they have sensitive periods. So parts of your brain have different sensitive periods during which they're growing at various rates, and during those sensitive periods that portion of your brain is especially susceptible to certain stresses, to certain stimuli. Right, it can be a positive stimulus or a negative stimulus, but during these sensitive periods is extremely susceptible to modification based on the environmental stressors that it experiences. So in terms of the power of the human brain, it's kind of fascinating.

Speaker 1: 5:51

We have 22,000 genes in our genome, all of which are going to be expressed at some point during the development of our brain, like we talked about when we were talking about the diathesis stress model. If you think about your genome as sort of this sheet music, then the experiences that we have in the environment allow us to make some notes. Right, we're going to play this section faster, that section slower. You know, this section louder, that section softer. Those notes on our sheet music is the changes in the expression of those genes. So as our brain develops, the way that the architecture unfolds is being changed by the epigenetic responses to the stressors on the genes in our genome. So, as we're thinking about brain development and we're thinking about how our brain reacts, as it's growing, to the experiences in the environment, our brain, our body is preparing us for the environment in which it thinks we're going to have to exist. That's how the changes are made, that's how the body adapts.

Speaker 1: 6:47

So, as we talked about in the prior episode, if an infant is being placed in situations of extreme neglect, for example, the brain is preparing itself to experience life in extreme neglect. That is an allocation of resources that is not necessarily optimal, right, that's not optimal for a child who is going to live in this world hopefully not in a situation of extreme neglect. It has trade-offs and that trade-off is going to have some negative implications for a child as they grow and mature. So, ultimately, we develop approximately 40% more neural connections than we're going to wind up having when we're adults, because what happens is the neural connections that we don't to wind up having when we're adults, because what happens is the neural connections that we don't need are pruned.

Speaker 1: 7:32

When we aren't using neural connections, the brain says well, this is not an efficient allocation of resources and it gets rid of those pathways. Instead, it takes the available resources and it strengthens and speeds up the neural pathways that are used the most. It's kind of a use it or lose it situation, and this is what. That use it or lose it situation kind of looks like You've got billions of brain cells. Those are the brain cells called neurons and they send electrical signals that communicate with each other. Now, as these connections form circuits, they become the basic foundation of your brain's architecture that we've been talking about. These circuits, these connections, they grow at this rapid pace and they're reinforced by repeated use. Connections that are used more often grow stronger and more permanent. But connections that aren't used that often, they get pruned, they start to fade away. Low-use circuits create these really fast lightningick pathways. First you get these simple circuits that form. They provide a foundation for more complex circuits that get built on later. Throughout the process, neurons form strong circuits and the connections for things like emotions, motor skills, behavior controls, logic, language and memory, and that all happens during this early critical period of development that we're discussing.

Speaker 1: 8:49

Here's a pretty fascinating example of that concept in rats. Now, a lot of the studies that I see when I'm trying to get prepared for one of these videos are rodent studies, because you can do things with rodents and experiments that you can't do with humans. But in this example we're talking about rodent auditory development. Now, initially, rodents are able to hear all sorts of different frequencies. This diagram that you're looking at shows how early experiences, extreme early experiences, can disrupt a rat's ability to hear different frequencies. Now, early on, if you look towards the left at A, you'll see that there are all these different colors right and you have this big red color that's circled. We're going to be looking at that more in a minute. But next to the red you see these different colors yellow, greens, blues. These are the various frequencies that a rat can hear and you can see the different hertz levels on the right in that bar graph. Now, early on, the rat can hear all sorts of different frequencies, can hear that entire range. Look at B. But if, for whatever reason, a rat is no longer provided with the full range of those frequencies, the brain is going to stop being able to hear them, literally stop being able to hear the full range of frequencies. And so, as you get to see on the right-hand side, when they've been exposed to these extreme early experiences, the rat's brain can no longer hear the full frequencies. You don't have all the blues, you don't have the greens, you're really just left with that red area. That's the majority of what's left, because that's all the rats can hear. Okay, now here's the interesting thing it's not an efficient allocation of resources for the brain to remain capable of hearing the frequencies that it's never gonna hear.

Speaker 1: 10:35

That same concept applies to us. It applies to your kid. If your child is not using certain neural pathways, then those pathways are going to shrivel up and eventually be pruned. The pathways that the child uses a lot are pathways that are going to be strengthened Think about this as a co-parent that are going to be strengthened. Think about this as a co-parent. Which pathways are you encouraging to grow? Are you encouraging neural pathways that are positive, that are the result of good parenting, to emerge? Are you encouraging those pathways to be strengthened, to be sped up, or is your child not having the kinds of experiences that we would hope a child has? Is your child focused primarily on dealing with stressors, on having their body receive environmental stress, fear being neglected and realizing that they're not going to be receiving the assistance that they need. And so other neural pathways that are the result of neglect are being reinforced and sped up.

Speaker 1: 11:34

Even though your child may be too young to understand what's going on, even though your child hasn't developed speech, even though you don't necessarily have the concept that your child actually knows the kinds of things that are being said or done around them, your child feels it right. Your child's body reacts to stress. Your child's body reacts to conflict, even though they can't necessarily tell you that there's conflict going on. Even if 10 years from now, they wouldn't be able to remember that they were exposed to co-parenting conflict or physical arts of altercation or yelling and screaming or neglect and things like that. Even though they won't be able to verbalize those things to you as they get older, their body remembers it. The neural pathways that are essentially selected will remember it. The neural pathways that are pruned and gone that would have been positive. Those are gone.

Speaker 1: 12:27

So, as you're interacting with your child, as you're interacting with your co-parent in the presence of your child, think about what you are doing to the presence of your child.

Speaker 1: 12:36

Think about what you were doing to the development of your child's brain architecture. There are good things and bad things that we can do to help our child's brain develop. The things that are bad for you as an adult, the things that cause you stress, that makes your heart race, that makes your blood pressure go up, that makes your heart race, that makes your blood pressure go up, that makes your palms sweat, that gives you that sense of dread those are all things that impact your child too. Just because they're too young to tell you that they're feeling it doesn't mean their body doesn't feel it. So I'm going to get more into some details of this and some studies that I think are quite fascinating as we get into further podcast episodes. In upcoming episodes, we're going to talk about the positive things that you can do that can have good results on your child's brain development. We're also going to talk about things that are negative for your child's brain development. In the meantime, I hope everybody has a great week and I'll talk to you all soon. Thanks,