Mean ± SEM a active and b inactive lever presses for amphetamine (0.1 mg/kg/infusion) between EC, IC, and SC rats during FR-1 responding following MTEP (0.3, 1.0, 3.0, 5.0 mg/kg) or saline. Pound signs (#) indicate that EC rats treated with 3.0 mg/kg MTEP, and all rats treated with 5.0 mg/kg MTEP exhibited less active lever responses than saline counterparts. Caret sign (^) indicates that following 5.0 mg/kg MTEP, IC rats displayed significantly more active lever presses than SC rats. Asterisk (*) indicates that IC rats administered 3.0 mg/kg MTEP exhibited significantly more active lever presses than EC and SC rats administered 3.0 mg/kg MTEP (p<.05). b There were no significant differences in inactive lever responding between EC, IC, or SC rats under any MTEP dose