shows the schedule of drug treatment for the four experimental groups. Locomotor activity was recorded on experimental Days 1–7, 12–14, 37–39. The numbers in the first column (2.5, 5.0, and 10.0) refer to MDMA doses (i.p.). Amph = 0.6 mg/kg amphetamine. Amph/MPD: On experimental Day 39, animals in each group were given either 2.5 mg/kg methylphenidate (N = 3/group) or 0.6 mg/kg amphetamine (N = 6/group).