An analysis of behavioral strategies used for recovery of function on the foot-fault grid task following sensorimotor cortex lesions in rats

Abstract

The goal of the present study was to determine the behavioral strategies used by rats to aid in the recovery of forelimb placing on the foot-fault grid task following unilateral lesion in the somatic sensorimotor cortex. Specifically, it was hypothesized that rats were utilizing up to two possible cues to aid in recovery: a cue of grid spacing and a cue of proprioceptive feedback learned from the improper extension of a forelimb through a grid hole (i.e., a foot-fault). In order to test these cue hypotheses, four different grid surfaces were used during preoperative and postoperative practice: a standard grid, a grid with small grid rung spacing, a grid with a shallow floor, and a grid with both small grid rung spacing and a shallow floor. Results indicated that both intact rats and rats with SMC lesions use the grid spacing cue and the cue of proprioceptive feedback from improper extensions of the forelimb in order to aid recovery. Furthermore, intact rats may learn cues of grid spacing, even when they are prevented from making improper forelimb extensions through a grid hole. On the other hand, rats with SMC damage may be required to learn cues from improper forelimb extensions before they can utilize cues of grid spacing.