Since there seems to be some confusion, I'll restate what you are saying a bit because it's important. Increasing activity in a brain region doesn't necessaril

Since there seems to be some confusion, I'll restate what you are saying a bit because it's important. Increasing activity in a brain region doesn't necessarily make it "thick and healthy", no matter how much you do it. This is the "exercise model" and it is a hypothesis (if not still at the conjecture stage, not my field).