SUMMARY
Proprioception and vision are two important sources of feedback involved in movement control To investigate the role played by proprioceptive feedback in movement control, researchers have used several experimental techniques to remove proprioceptive feedback. The most direct method involves surgical deafferentation. When animals have been deafferented after having learned a skill they continue to perform certain skills, although with distinct performance-capability limitations Humans who have been deafferented because of joint replacement surgery or neuropathies, or who have simulated deafferentation from a nerve block procedure, show similar characteristics. In addi tion, researchers have vibrated the tendon of the agonist muscle during movement to distort propri oceptive feedback. Results of these approaches have shown that proprioceptive feedback is impor- tant for controlling the degree of precision in limb movements, for timing the onset of motor com mands, and in the coordination of body and limb segments.