Isodirectional conditioning effects of d-amphetamine and pentobarbital on schedule-controlled operant behavior in...

Pigeons were trained to peck a key on a multi FR30-FI3' schedule. Presession injections of d-amphetamine (2 mg/kg) and pentobarbital (7.5 mg/kg, 10 mg/kg) were paired with presentation of a red light on the ceiling of the operant chamber. After the five pairings separated by two saline sessions in which a white light was lit, the red light was presented without drug injection. The red light came to cause an isodirectional (drug-like) effect on operant behavior. When the red light was paired with drug injections and operant behavior was prevented from occurring, the light did not acquire isodirectional conditioned effect. Thus, responding in the presence of the drug effect is necessary to establish the conditioning.