Effects of punishment on choice between cocaine and food in rhesus monkeys
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- Negus, S.S. Psychopharmacology (2005) 181: 244. doi:10.1007/s00213-005-2266-7
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Punishment is widely used in an effort to control drug-taking behavior; however, only a few preclinical studies have investigated the effects of punishment on drug self-administration. Such studies may contribute to more rational use of punishment to control drug use.
To evaluate the effects of punishment on choice between cocaine and food in rhesus monkeys.
Rhesus monkeys were trained under a concurrent-choice schedule of food delivery (1 g pellets, fixed-ratio 100 schedule) or cocaine injections (0–0.1 mg/kg per injection, fixed-ratio 10 schedule). Full cocaine choice dose–effect curves were determined under baseline conditions and under test conditions in which a putative punisher (intravenous histamine injection; 0.0032–0.032 mg/kg per injection) was paired with either food or cocaine delivery.
Under baseline conditions, cocaine produced a dose-dependent increase in cocaine choice. Histamine functioned as a punisher of both food- and cocaine-maintained responding. Pairing histamine with food delivery reduced food choice, increased cocaine choice, and produced left shifts in the cocaine choice dose–effect curve. Conversely, pairing histamine with cocaine decreased cocaine choice, increased food choice, and produced right shifts in the cocaine choice dose–effect curve. The magnitude of histamine’s punishing effects was directly related to histamine dose and probability of histamine delivery, and inversely related to the magnitude of the reinforcer.
These results demonstrate that a primary effect of punishment in the context of food vs cocaine choice is not only a decrease in the behavior being punished, but also an increase in the unpunished alternative behavior.