One problem with leg prostheses is that they can feel too heavy. Connecting a prosthesis to the nervous system can change that, researchers say.

Even after a year of wearing and using a prosthetic device, participants in a new study still had a mismatch between what they did and what they felt.

"Until we can understand each component, we can't expect to take the brain apart and put it back together again in order to figure out how it works."