(A) Horizontal locomotor activity (beam breaks) for the first 30 minutes following administration of saline (SAL, 1.0 ml/kg) or escalating AMPH doses (0.5, 1.0, 2.5, 5.0 mg/kg) on the first (Day 1) and fifth (Day 5) injection day of each dose week in adolescent rats maintained on the control diet (CON), n-3-free diet (DEF), and fish oil-fortified diet (FO). (B) Horizontal locomotor activity following administration of SAL or escalating AMPH doses on the first day of each dose in rats maintained on CON, FO, or DEF diets. Values are group mean beam breaks ± S.E.M.