Cerebellum in action

“It’s not just sequence but the skill, said Arbib. www.usc.edu/programs/neuroscience/faculty/pro file.php?fid=16 As he reached for a cup of coffee, he said: “Take an example from manual skill. We’re actually done models of the cerebellum where we reach for a cup. What you’ll see is just one smooth movement when my opposing fingers reach the cup at the same time.” But he explained that if the cerebellum was damaged, it would be so easy:

“You’d have to decompose it in two movements, because you can’t coordinate the timing. So if you tried to do it, you might end up having the fingers too close when you hit the cup, or too far apart when you reach the cup. In other words, you run the risk of knocking the cup over. So instead, what do you do? You very quickly compensate for your understanding of your deficit, and you reach out and you get, let’s say, thumb contact, and then you will close the hand. In other words, you break the thing down into pieces that you know you can succeed with, and then your resynthesize the sequence that will get you to your goal. But each gesture is itself less skillful than it would be if you execute it with [an undamaged] cerebellum.”

This implicated yet another part of the brain. “You can get the sequence right without the cerebellum, but if you want a smooth performance, you need a cerebellum. It cues each moment, and it coordinates the movements,” he said. ‘You can’t do language without a cerebellum” ~ Page 190