Your brain can change itself. That statement in itself is kind of amazing. How many machines or devices or computers or phones that exist that you know of can change themself? Well, the answer is none. There are no computers or machines out there that can do that, but your brain can.
It changes its structure and function in response to the experiences you have across your entire lifetime. Your emotions, your memories, your actions, all of your behaviours at any moment can change the trillions of connections between the billions of neurons that exist inside your head. Because of this change across your whole lifetime, that makes your brain, the structure and function of it, completely unique, so that makes you unique.
There is no brain that has come before or that will exist in the future that is the same as your brain. No brain and no other person has the same experiences that you have which have ultimately shaped the structure and function of your brain. That's what this blog is about, and there's three different ways in which your brain can be shaped by your experiences that I want you to take away from this blog.
The first one is how this whole process works. This process that we call brain plasticity, the way in which the structure and function of your brain changes across your entire lifetime - from birth through to the end of life, and the way that's different across those different timescales. The second how this brain plasticity works, how it shapes the structure and function of your brain and changes those connections between different neurons. Finally, and perhaps the most exciting aspect of this particular blog is these new, speculative techniques, that are being developed by neuroscientists to try and promote plasticity when we reach adulthood. That is, trying to put your adult brain back into a juvenile-like state, where you can learn like you did when you were a child, but inside an adult's body. That's the final aspect of the blog.
The really major changes to your brain, this brain plasticity, happen during your childhood. Soon after you're born, all the way through to about nine to ten years of age, that's what we mean when we say childhood. This is when the brain really is most prepared to learn new information and learn new skills. You're honing your senses, your vision, your hearing, and so on. You're learning to walk. You're learning to run. You learn to communicate both verbally with language and non-verbally with your body, and you're learning a new language as well.
At this point, you have the capacity to learn any language that you want. It's also when your attachments are formed with your caregivers, your siblings, your peers, and also when your emotional wellbeing and intelligence are put in place. At birth, we're born with as many neurons and connections between neurons in our brain that we will need for the rest of our life.
That's an incredible fact. We don't actually need any more neurons or need to grow any more neurons from when we're born. At birth, each neuron in your cerebral cortex, which is that part that sits on top of the rest of your brain, the superficial part of your brain, has about 2,500 synapses, or connections, to other neurons in your brain. But by age three, that number has grown to 15,000 connections. You've already grown many more connections than you had when you were born.
The brain over-delivers at this point in your development. It throws out a net of all these connections that you might need in your brain to essentially learn anything. It doesn't know what environment you're going to land in. It doesn't know what household you're going to arrive in at birth, it just knows that it needs to set up this learning machine.
It doesn't know, for example, whether you are going to be born into a Spanish household, Japanese household or Chinese household, so it sets up all your connections to learn any language that you might need to in that particular household. You have more connections in your brain than you're going to need, and you keep connections by using them and learning.
You have a heightened capacity for learning during childhood. There are what we call windows of opportunity to get really good at learning those critical behaviours that are important for later in life. We have different windows of opportunity for different neural circuits in our brain that control different behaviours in the environment.
The timing of those windows of opportunity are actually optimized for when it's best to learn that behaviour, whether it be language, seeing or hearing. But as a rule of thumb, the brain develops back to front. It starts right at the back in the visual parts of the brain and gradually moves its development forward, all the way forward to the frontal part of your brain to an area called the prefrontal cortex.
Therefore, the behaviours that you develop reflect the order in which your brain develops. The first thing to develop are your sensory functions, like vision, hearing, touch and smell. Then what comes next is your ability to move around in your environment, walking, running, and also your language, both verbal and nonverbal.
Finally, you develop higher order cognitive functions or higher order conscious rational thoughts, which are controlled by the front part of your brain in the prefrontal cortex. There are critical time windows, for us to learn these behaviours. If we don't learn them within those time windows, then some behaviours may actually be impaired or completely lost later in life.
How does this neuroplasticity work? How do we form new connections in our brain? Well, the more we learn new skills and behaviours, emotions, and repeat them, the stronger and securer these synapses become. These connections become more and more ingrained in your brain. It's very much like the more you use your neurons and connections, the stronger they become.
Neurons and connections that are rarely or never used during development actually end up dying off later on. This follows what we call a “use it or lose it” principle. So the more you use connections, the more they survive and the less you use them, the less they do. This isn't a passive process for the brain. During your childhood and through to adolescence, the brain actively prunes back, actually cuts back the connections, the pathways in your brain that you're not using for particular behaviours.
The brain sets out all of these connections just to give us the potential to learn anything. Then we start using some of them to learn particular things, like a language. Then the pathways and connections we're not using, they get actively cut back or pruned back by the brain. This is why an adult has about half the number of synapses or connections than a three year old. We're just left with the brain pathways that we've actually used.
To give you a tangible example, if you compare the brain of someone who's learned to read with someone who can't read later in life or even in childhood, the structure and the function of their brain looks completely different. The person who's learned to read has the connections, neurons and the pathways that allows them to interpret the visual aspects of a word and what that word actually means. Whereas the person's brain who hasn't learned to read, just doesn't actually have those neurons, doesn't have those connections, doesn't have those brain pathways that allow you to perform these aspects of reading.
During adolescence, there's significant brain growths in the teenage brain. Synaptic pruning actually begins at the back of the brain and works its way forward to the front of the brain. This is really critical because it means that in a teenage brain the frontal areas, which we know are really important for conscious rational thoughts and regulating our emotions, aren’t fully developed. Perhaps most importantly, not just that it's not fully developed, it's not fully connected up with the rest of the brain. Why that's important is because this part of the brain is typically heavily connected to the emotional parts of the brain. One of its roles is to regulate the emotional parts of the brain.
What you find in teenagers is that because these connections aren't there, they rely much more heavily on the emotional parts of the brain than we do as adults. Emotional brain structures, like the amygdala, which sits in the limbic system, are heavily involved in how we process emotion, how we perceive emotion, our emotional memories. They're really a much older part of the brain in which we would have used in fight-flight-freeze situations.
When you start to think about the teenage brain in that way, it makes you realize they don't have the brain connections yet, or the brain capacity to actually regulate their emotions. This explains quite a lot about why they're often so emotional, can be so irrational, can sometimes be aggressive, can sometimes be very risk taking in their behaviour and even impulsive.
You can't really pin it on them. It's actually because their brain isn't fully developed and particularly not good at managing and regulating their emotions. This is a very important issue, obviously for parents, teachers, and teenagers themselves, and also incredibly complex. Consequently, we've actually put together a whole course to help you understand the teenage brain.
Up until relatively recently, we thought that as you moved out of the teenage years into adulthood, and then into old age, that the brain was fixed, it didn't change itself, that the connections between those different neurons are fixed and are not malleable. But actually, research has shown over the last 10 to 15 years that the brain never stops changing. It's constantly changing and is constantly learning.
As we age, there's no doubt that this neuroplasticity, the ability of the brain to change its structure and function, does decline with age, but it doesn't stop, it doesn't halt completely. New neurons can appear in different parts of the brain right up until the day that we actually die. This plasticity is there from cradle all the way through to grave.
You might wonder about different ways in which you can promote that plasticity, and there are actually many quite easy ways to do that. Wellbeing activities like exercise, meditation, getting good sleep, healthy eating can really help with promoting plasticity. Plasticity itself can also help with actually repairing the brain after it's been diseased or damaged by a stroke or trauma.
If you're really interested in understanding and learning about those strategies, you could take our other signature course, which is called Brain Health and Mental Wellbeing, in which we cover in detail exactly how you can promote brain health and plasticity to help your wellbeing.
One of the most exciting developments in neuroscience in the last few years has been the development of techniques that actually promote plasticity in our brain. This is trying to put the adult brain into perhaps a juvenile-like or childlike state to encourage the same kind of structural and functional changes to the brain that we see in a child, but in an adult brain.
Imagine having the learning capacity of a child, but in an adult. The things like learning to speak multiple languages, for example, that you can do as a child. Or rapidly learning a language, learning how to play the piano, learning all those motor skills like running and walking, and so on that you have. But imagine doing that as a 70 or 80 year old where we're using these techniques to promote plasticity.
This is one of the most exciting developments in neuroscience where we're not a million miles away from these techniques being available. But lots of them are speculative at the moment and being used in animal models. But I just wanted to share a few of them with you.
The way nearly all of the techniques work is that they try to remove the brakes that are put on plasticity as we move into adulthood. The brain actively puts on brakes to slow down plasticity as we get older. It does that both in a functional and structural sense, and all these techniques try and remove those breaks.
For example, things like sitting in the dark for long periods has been shown in animals to remove some of the structural breaks on neurons trying to form new connections. Other techniques like pharmacological manipulations, drugs, and brain stimulation have encouraged functional changes, the balance between how excited or how suppressed or inhibited the brain becomes to promote plasticity in adulthood.
But perhaps the most promising techniques are a combination of some of the techniques you might be familiar with like learning and brain training techniques to help you encourage and improve your abilities, and maybe memory abilities with some pharmacological manipulation or brain stimulation. They seem to be the most promising for promoting this childlike plasticity in adulthood.
But one note of caution with these techniques is there's a bit of an ethical dilemma because perhaps you don't want too much plasticity. Perhaps there's a reason why the brain has put these brakes in place so that our brain doesn't become out of control with too much learning as we get older. The brain is always trying to find this balance between stability, the habits that we have formed which we perform over and over and over again, and plasticity the ability to learn new things. We might not want to disrupt that balance too much with these new techniques.
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