Effects of chlorpromazine on rats' acquisition of lever-press responding with immediate and delayed reinforcement.
The effects of chlorpromazine (0, 2, 6, and 10 mg/kg) on the acquisition of lever-press responding by rats were examined under conditions where reinforcement (water delivery) was immediate or delayed. Under the immediate reinforcement condition, water-deprived rats were exposed during 8-h sessions to a fixed-ratio 1 (FR 1) schedule of water delivery without prior autoshaping or hand shaping. Under the delayed reinforcement condition, similar rats were exposed to a tandem FR 1 fixed-time 8-s schedule of water delivery. A different squad of eight rats was exposed to each delay condition and drug dose. For all subjects, responses on one lever produced water and responses on a second lever had no programmed consequences. Regardless of whether reinforcement was immediate or delayed, chlorpromazine reduced in dose-dependent fashion the mean number of operative-lever responses emitted, which suggests that the drug interfered with learning. At all chlorpromazine doses except 10 mg/kg, substantially more operative-lever than inoperative-lever responding occurred, indicating that the operant response was acquired. Chlorpromazine at 2 and 6 mg/kg disrupted the acquisition of stimulus control by the operative lever when reinforcement was delayed, but not when it was immediate. At 10 mg/kg, most subjects did not acquire lever-pressing regardless of whether they were exposed to the immediate or delayed reinforcement procedure. Procedures similar to those used in the present study appear to provide a reasonable assay for examining how drugs affect the initial behavioral effects of immediate and delayed reinforcement, and may merit further investigation.
Byrne
T
T
Department of Psychology, Western Michigan University, Kalamazoo 49008, USA.
Lesage
M G
MG
Poling
A
A
D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology*; D002746:Chlorpromazine / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule
D014150:Antipsychotic Agents; D002746:Chlorpromazine