What rewires patients’ brains is not mitts and slings, of course. Though they force the patients to practice using their damaged arms, the essence of the cure is the incremental training or shaping, increasing in difficulty over time. “Massed practice”—concentrating an extraordinary amount of exercise in only two weeks—helps rewire their brains by triggering plastic changes. Rewiring is not perfect after there has been massive brain death. New neurons have to take over the lost functions, and they may not be quite as effective as the ones they replace.
