[MUSIC] Okay, so I want you to understand how limiting the basal ganglia is. So, let's just do an experiment. Is it easy to do this? Yes, let's all do this together. Yes, we can do this. Now let's do this. That's easy, too. Now, I'm going to move this arm like this, and this arm like that, and you can see I cannot do it. Okay? I'm, I cannot do an asymmetrical movement. Both movements, this one and this one, are easy. [LAUGH] Putting them together is actually not challenging in any physical sense. It's not going to make me fall down. It doesn't require any more energy than doing this, but something's stopping me. Something's screwing up that, that combination. I can't do it. I could do it if I practiced a lot, and in fact the example that I used to use was rubbing my stomach and patting my head. But what I found is that the 20-something medical students that I teach all can do that. I, I can't. But, in any case, you can do all these movements. You can learn how to do them. And we're going to see how you can learn how to do them. But the fact that you can't do them. There's nothing hard about it. There's nothing motoricallly hard about it. What stops you? The basal ganglia. Your brain is stopping you from motorically multi-tasking. [MUSIC]