Dr. Nico Dosenbach often prescribes CIMT (constraint-induced movement therapy) to his patients with disabled arms or hands. The idea is to keep the stronger arm still, so that the patient has to use their other one. To have a better idea of how and why it works, he decided to do an experiment on himself: he put one of his own uninjured arms in a cast, then had his brain scanned to see how it adapted. What he found was that in just a few days, his brain had reorganized.
Read more here about this fascinating experiment on NPR.org