Corticospinal correlates of fast and slow adaptive processes in motor learning

Imagine you’re learning to play basketball for the first time. At first, it feels a little clumsy, but the more you practice, the better you get. How does this happen? Well, scientists believe that our brains have different ways of learning new things, each one working at its own speed.

In our study, we decided to test this theory. We had 16 people do a task where they had to reach for something, while we used a special device to send harmless magnetic pulses to the part of their brain that controls movement.

We focused on two key responses in the muscles of their upper arm: the motor-evoked potential (MEP) and the cortical silent period (CSP). Let’s break down these big terms. An MEP is a measure of how much your muscles respond when the brain sends a signal. In other words, it’s a measure of how “loud” the brain’s message to the muscles is. The CSP, on the other hand, is a brief moment when the muscles don’t respond to the brain’s signals at all, like a brief pause in the conversation between the brain and the muscles.

Our results showed that these two responses are connected to different types of learning. The MEP, or the “loudness” of the brain’s message, seemed to change quickly as people learned the task, but also faded quickly once the task was over. It’s like quickly picking up how to dribble the ball in basketball: you might get the hang of it quickly, but if you don’t keep practicing, you can easily forget.

On the other hand, the CSP, or the “pause” in the conversation between the brain and muscles, seemed to change more slowly as people learned the task, but these changes stuck around longer. This is similar to learning the rules of the game in basketball: it takes more time, but once you understand them, you’re unlikely to forget.

In other words, our study suggests that when we’re learning new things, our brain doesn’t just have one way of adapting. Instead, it uses multiple ways that work at different speeds and have different strengths. This research helps us understand better how we learn and improve at things like sports, playing an instrument, or any other skill that involves movement.