Sensorimotor systems are not rigidly wired predetermined networks but rather highly plastic structures that learn and modify their entire performance in response to changes in external or internal conditions. Lesions or distortions of the system's input, which initially cause a functional disorganization, induce an active reorganization which often leads to a recovery of function. Examples of lesion-induced neural plasticity have been known for some hundred years; however, an awareness of their value as research tools is relatively new. This current interest is a consequence of rapid ly...