(A) Premature responding. (B) % accuracy. (C) omissions. Rats were injected with vehicle (Veh), yohimbine (Yoh) (1.25 mg/kg) or nicotine (Nic) (0.3 mg/kg) and tested in the 5-CSRTT on two separate tests. Prior to the first test, they were injected with the vehicle for nor-BNI (open bars); prior to the second test, they were injected with nor-BNI (10 mg/kg) (closed bars). Values are mean±SEM. * Different from vehicle (0 dose nor-BNI), p<0.05, vehicle: n=5, yohimbine: n=7, nicotine: n=5.