Implications of the learned nonuse formulation for measuring rehabilitation outcomes: Lessons from constraint-induced movement therapy.

Objective: Research on monkeys with a forelimb from which sensation is surgically abolished demonstrates that such animals do not use their deafferented limb even though they possess sufficient motor ability to do so, a phenomenon labeled learned nonuse. This dissociation also occurs after neurological injury in humans. Instruments that measure these 2 aspects of motor function are discussed, and the implications of this work for cognitive assessment are explored. Study Design: Literature review. Results and Conclusions: The effects of a neurological injury may differ widely in regard to motor ability assessed on a laboratory performance test in which movements are requested and actual spontaneous use of an extremity in real-world settings, indicating that these parameters need to be evaluated separately. The methods used in Constraint-Induced Movement therapy research to independently assess these 2 domains are reliable and valid. An extensive program of research conducted by Edward Taub with monkeys from whose forelimbs somatic sensation had been surgically abolished has shown that when injury to the nervous system takes place, there is potential for chronic disuse of a body part or function to occur that is in excess of what is warranted by damage to the physiological substrate (summarized in Taub, 1977). Experiments in this line of work designed to rule out alternate mechanisms (e.g., interlimb inhibition of movement) indicated that establishment of such an excess motor deficit is supported by the following conditions: (a) organic damage that results in an initial inability to use a body part so that an animal is punished (by failure) for attempts to use that part of the body and rewarded for use of other parts of the body and (b) slow recovery from or healing of the organic damage so that the animal recovers the physical ability to use that body part, but the conditioned suppression of use that developed in the acute phase remains in force. Other experiments demonstrated that this type of motor deficit, termed learned nonuse (Taub, 1977), could be overcome by repetitive practice in using the impaired body part or function; this procedure counterconditions the behavior learned in the acute phase. These findings have significant relevance for treatment and measurement of motor impairment in humans after central nervous system (CNS) damage and other injuries (Taub, 1980; Taub & Uswatte, 2000). Among the implications for the treatment of motor impairments