> You get better at modeling the trajectory because the neurons physically move closer together as you learn

I think "modeling the trajectory" is not necessarily what we are doing either. It's more likely we are using much simpler heuristics. If you are trying to catch a ball flying through the air, you can just look at the ball and modulate your running speed to keep your eyes at a fixed angle until you catch the ball. It's much more analogous to a PID controller than a model of the trajectory.