That Neuroscience Guy - How do we become experts?

Episode Date: March 22, 2021

You've probably heard that 10,000 hours of practice makes us an expert at something. But why is this the case? In this episode, we discuss the neuroscience of becoming an expert. 

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. You might have heard of the importance of 10,000 hours. It's become a magic number. The idea that it takes 10,000 hours to become an expert at something. But what does this really mean and what's the neuroscience behind this? Today, we're going to talk about the neuroscience of synaptic plasticity. Perhaps the most important way that we learn is through repetition. Despite some pushback on repetition learning in the school system,

have you ever seen an Olympic or professional athlete who did not practice a lot? For that matter, have you ever heard of a chess grandmaster who had not played a lot of chess or world-class mathematician who had not done a lot of math. The original study that lies behind the 10,000-hour rule in synaptic plasticity was done by K. Anders Ericsson and colleagues. In their study, they had three principal groups of participants. They had music teachers, they had professional musicians, and then they had world-class musicians. So it's important to note that the least experienced people

in the original Anders Ericsson study were music teachers. And what they did was they asked these people to recall throughout their life how much time they'd spent engaged in practice. And this was their principal finding. They found that what separated the world-class experts from the other two groups, the professional musicians and the music teachers, was hours of practice. And in this particular study, it took the experts about 10,000 hours to become world-class experts by the age of 20. There's an important note here that a lot of people miss. It's not just 10,000 hours of practice, it's 10,000 hours engaged in deliberate practice. I'll talk more about that later on another episode, but it's important to realize that if you're not practicing effectively, in other words, you're not engaged in deliberate practice,

then 10,000 hours might not make you a world-class expert. So we know that 10,000 hours makes you an expert, but what's happening in the brain and how does this relate to synaptic plasticity? To understand this, we're going to have to talk a little bit about how a neuron fires. Essentially, the neurons within the brain most of them are interneurons are just connected to each other and aren't connected to neurons that go out to contract muscles or bring in sensory information and these interneurons result in everything how we process visual information how we decide what we're going to have for dinner, the emotions we experience. Anyway, the way they function, like I said, is pretty simple.

Information comes in to the cell nucleus of a neuron along dendrites or pathways, and that information is basically electricity or an electric charge. These electric charges are specifically called excitatory postsynaptic potentials, or EPSPs, or inhibitory postsynaptic potentials, or IPSPs. The excitatory postsynaptic potentials increase the charge in the nucleus, and the inhibitory postsynaptic potentials decrease the charge. Now, if there's enough electrical inflow, so there's more EPSPs than IPSPs, then basically the nucleus reaches a threshold and the neuron depolarizes or fires. What that means is an electrical signal called an action potential is sent down the axon. This is the outgoing communication branch of the neuron.

is sent down the axon. This is the outgoing communication branch of the neuron. And at the end of the axon, where it connects to dendrites of other interneurons, neurotransmitter is released. It's an important point. It's not an electrical charge that just goes down a wire. It's actually an electrical to chemical to electrical process. The action potential is electrical in nature. When it reaches the end of the axon, neurotransmitter is released, and that neurotransmitter attaches to the postsynaptic neuron or the dendrite in a process called binding, and that binding creates those EPSPs and IPSPs that we talked about. And away we go. The electrical signal is conveyed. Now, the reason I'm talking about how a neuron fires is because it's really important to understanding memories, synaptic plasticity, and the 10,000-hour rule. So, what's a memory?

Essentially, a memory is just the strengthening of neural connections. Essentially, a memory is just the strengthening of neural connections. I'm going to give you a really simple example. Imagine you want to build an association between the picture of a dog, what a dog looks like, and the verbal representation, the word dog itself. And to make this simple, imagine that this is just represented by two neurons. There is a single neuron that when it fires is the picture of a dog, and there's a single neuron that when it fires is the word dog. And these two neurons are attached. The axon of the dog neuron attaches to one of the dendrites of the word neuron.

And what you want for a memory, that association between the picture of a dog and the word of a dog, is when the picture neuron fires, you want the word neuron to fire. So you want that neural connection to be stronger. And if it is stronger, that's a memory. Now like I said, that's a simple example with one neuron attached to another neuron, but it scales up. example with one neuron attached to another neuron, but it scales up. Imagine the tens of thousands, if not hundreds of thousands, of neurons that are used to represent the picture of a dog and the same number of neurons that are used to represent the word dog. You want to strengthen all of the connections between these neurons to build that association. So how does this happen at the neural level? How

do we strengthen these connections and form memories and get synaptic plasticity? Well, when the pitcher dog neuron and the word dog neuron fire at the same time, the synapse or the connection between these two neurons is put into a state of long-term potentiation. is put into a state of long-term potentiation. Basically, what that means is if the pitcher neuron fires, it's more likely that the word neuron will fire, or vice versa. It's also important to note that this only occurs if the timing is very similar. For this to work, the pitcher neuron has to fire slightly before or at the same time as the word neuron. If it fires too early or fires too late,

then the state of long-term potentiation will not occur. This is called spike timing dependent plasticity. But basically what it means is the two neurons have to fire at approximately the same time. This was first shown by two researchers, Bliss and Lomo, where they artificially stimulated neurons and they found that if you provided a whole ton of stimulation, what is technically called tetanus, what you got was long-term potentiation. technically called tetanus, what you got was long-term potentiation. The firing of the input neuron resulted in a greater amount of activity in the postsynaptic neuron. Now this isn't the whole story. Long-term potentiation is only the in-between state or the middle ground. So let's summarize quickly before we move ahead. If you repeat something over and over again

like the association between the picture of a dog and the word dog, or if you repeat say your golf swing over and over again, the neurons that are involved in this enter a state of long-term potentiation. Now why this is important is what also has been shown is that long-term potentiation. Now, why this is important is what also has been shown is that long-term potentiation leads to synaptic plasticity, the long-term changes that are the strengthening of the neural connection. Now, what are those changes? Synaptic plasticity, or the permanent changes that occur between neurons binding them together, are typically evidenced in three ways. One way that synaptic plasticity is represented is an increase in the amount of neurotransmitter released.

If you think back to our neuron firing example, the action potential causes a release of neurotransmitter. And if you increase the amount of neurotransmitter that's released, you have a stronger connection. Another way that synaptic plasticity occurs is through an increase in the number of postsynaptic receptors. That neurotransmitter we just talked about being released, well, if you remember, it binds or attaches to dendrites. And there are receptors on those dendrites. And if you increase the number of receptors, then you have a stronger synapse because more neurotransmitter can bind. And last, you actually get growth.

In some instances, long-term potentiation leads to the actual growth of new neural connections, what's called sprouting. What's really amazing is you can actually see this now. Using what essentially is a really good microscope, photographs have been taken that actually show the process of sprouting occurring. And it occurs quite quickly, within a couple of hours. And this neural growth means more attachments, which again means a stronger connection. growth means more attachments, which again means a stronger connection. So, stronger connections, associations between things, whether it's a picture of a dog and the word dog, or whether it's between neurons that are used in your golf swing, are a memory. That long-term process is called synaptic plasticity, and it's brought about by long-term potentiation.

and it's brought about by long-term potentiation. So, how does that get us 10,000 hours? Well, if you practice more than someone else, the neurons involved will be in a long-term potentiated state more than other people. And because they're in that state more than other people, there'll be more synaptic plasticity. In other words, the neural connections might experience an increase in neurotransmitter release, an increase in the number of receptors,

or actual growth of new connections. And if that occurs, those neural connections get stronger. So unfortunately, Anders Ericsson was right. The only way to become an expert is by practicing a lot. And hopefully from this podcast, you've learned a little bit about the neuroscience behind that process. My name is Olive Kregolson, and I'm that neuroscience guy. You can check out my website at www.olivekregolson.com, or you can follow me on Twitter at that neuroscience guy. Thanks for listening. See you on the next podcast.