Punishment alters the discriminative stimulus effects of midazolam.
Experiment 1 examined the effects of punishment on the discriminative stimulus (DS) effects of midazolam (M) and pentobarbital (P) in 3 pigeons. Sessions began with a fixed-interval (FI) 3-min schedule of food reinforcement. After 40 min, either saline (S) or 0.56 mg/kg of M was injected. A drug-discrimination (DD) component began 10 min later. Pecking the left key produced grain after S injections, whereas pecking the right key produced grain after M. Dose-response curves for M and P were obtained under these conditions and also when every 30th peck during the FI was punished by shock. The introduction of punishment increased sensitivity to the DS effects of M and P. Experiment 2 examined whether a punishment history increases sensitivity to the DS effects of M. After DD training and testing, pecking was punished for 10 sessions. This history shifted the M dose-response curve to the left for 3 of 4 pigeons. These results emphasize the contribution of behavioral variables to the DS effects of drugs. Environmental variables appear to play a prominent role in guiding sensitivity to the subjective effects of drugs.
Tatham
T A
TA
Department of Psychiatry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799, USA. ttatham@mx3.usuhs.mil
Roden
M M
MM
Barrett
J E
JE
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D010856:Columbidae; D004193:Discrimination Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005502:Food; D018757:GABA Modulators / Q000494:pharmacology; D008297:Male; D008874:Midazolam / Q000494:pharmacology*; D010424:Pentobarbital / Q000494:pharmacology; D011678:Punishment / Q000523:psychology*; D012055:Reinforcement Schedule
D014151:Anti-Anxiety Agents; D018757:GABA Modulators; D010424:Pentobarbital; D008874:Midazolam