Quinpirole-induced locomotor activity in 12 10-min blocks (a) or in 120 min (b) in the quinpirole-induced hyperlocomotion test. All rats were injected with quinpirole (1.0 mg/kg, sc) and then measured for motor activity for 120 min. After 1 retraining (predrug) session, all rats were injected with risperidone (0.3 mg/kg, sc) and avoidance responses (c, d) were measured 60 min later. c shows data of all rats, while d shows only of those with avoidance > 50% on the predrug day. All data are expressed as mean + SEM. * p < 0.05 relative to the VEH group.