Amphetamine and task specific practice augment recovery of vibrissae forelimb motor function after unilateral cortical injury in the rat

Abstract

Research in this lab has shown that amphetamine and task specific practice during the period of amphetamine intoxication can produce a delayed, yet significant enhancement of forelimb placing ability in rats after cortical injury (Schmanke, 1992; Schmanke, Avery & Barth, 1993). The purpose of this experiment was to determine the relative contribution of amphetamine administration and task specific practice to recovery of forelimb placing ability in rats after unilateral electrolytic lesions of the sensorimotor cortex. Subjects were divided into groups receiving amphetamine (2mg/kg) plus practice, amphetamine only, saline plus practice and saline only. Groups of subjects receiving amphetamine and practice showed the greatest enhancement of recovery. Groups receiving amphetamine only and saline plus practice recovered at a faster rate than saline only controls. Statistical analysis suggests that amphetamine and task practice produce independent beneficial effects on recovery of forelimb motor function after brain injury. The purpose of the second experiment was to investigate the contribution of various components of forelimb placing practice during the period of drug intoxication to the amphetamine enhanced recovery process. After unilateral electrolytic lesions of the sensorimotor cortex, subjects were divided into groups receiving amphetamine injections (2mg/kg) and ipsilateral, contralateral, vestibular or no practice during the period of drug action. Groups of subjects receiving ipsilateral or contralateral practice recovered significantly faster than the other treatment groups. The vestibular practice group recovered at a faster rate than no practice control subjects. These data suggest that contralateral sensory or ipsilateral sensory and motor experience can augment amphetamine enhanced recovery of forelimb motor function in rats.