In the pharmacological studies, risperidone at a dose of0.3 mg/kg, but not at the lower 0.1 mg/kg dose, amelioratedamphetamine-induced hyperactivity in a 30 min test session without affecting activity levels of non-amphetamine mice [Fig. 2;ANOVA by Amphetamine by Risperidone: Amphetamine effect:F(1,60) = 18.7, p < 0.001. Risperidone effect: F(2,60) = 4.02, p = 0.023.Amphetamine × Risperidone interaction: F(2,60) = 1.0, p = 0.37].Risperidone had no effect on the other tests in the behavioral battery (Table 2).