The effects of cueing and amphetamine on recovery from the sensorimotor asymmetry following unilateral lesions of the anteromedial cortex in rats

Abstract

Following unilateral lesions of the anteromedial cortex (AMC), rats exhibit an ipsilateral asymmetry as measured by a bilateral tactile stimulation test (e.g., contacting an adhesive patch placed on the forelimb ipslateral to the lesion before contacting a simultaneously applied contralateral patch). A previous study demonstrated that a contralateral tactile cue presented 5s prior to the bilateral tactile stimulation test neutralizes this asymmetry, whereas, an ipsilateral cue retards recovery. It was hypothesized that cueing may direct attention and thus influence the sensorimotor asymmetry after AMC lesions. The purpose of the present study was to demonstrate a facilitation of recovery with contralateral cueing and to test the effects of amphetamine on recovery from the sensorimotor asymmetry after AMC lesions. Rats received unilateral electrolytic lesions of the AMC and the magnitude of the sensorimotor asymmetry was assessed beginning 24 hrs after surgery. On postoperative days 2, 4 and 6, rats received contralateral, ipsilateral, or no cueing and were injected 1 hr later i.p. with either 2mg/kg amphetamine or vehicle. Amphetamine was found to have no significant effect on the rate of recovery regardless of cueing condition. However, rats that received contralateral cueing exhibited an accelerated recovery rate as compared to both the ipsilateral and no cued rats. These data suggest that amphetamine does not significantly affect recovery on some tasks and that recovery from AMC lesions can be manipulated using cueing procedures.