Rats received either control saline, 6-hydroxydopamine (6-OHDA) or kainic acid (KA) unilateral lesions of 5 different foci in the neostriatum. Both KA and 6-OHDA lesions in the mid-ventral focus resulted in a substantial and prolonged impairment in sensorimotor orientation to contralateral stimuli. At all other placements 6-OHDA induced a temporary mild impairment, and KA had no detectable biasing effects. The results suggest that the neostriatum is topographically heterogeneous in the mediation of this particular aspect of sensorimotor performance.