Well, you'd have to remap all the sensory inputs (computers don't have that problem since they have standard interfaces). For instance, if you got put in a sma

Well, you'd have to remap all the sensory inputs (computers don't have that problem since they have standard interfaces). For instance, if you got put in a smaller body you'd keep reaching for things and coming up short; you'd have a different sense of balance; speech would be hard since mouth and vocal cords would be different shape and quality; lots of things like this. The brain is extremely adaptable and could theoretically learn to do this (esp with something like rehabilitation therapy), but trying to do it all at once would be a tall order. Basically instead of a computer's fixed API, you are continually negotiating a new interface between brain, body, and world with every action you take. Keeping it updated isn't hard but starting from scratch takes lots of trial and error (just watch a baby grow and you'll see what I mean).