William L Woolverton1, Karen G Anderson. 1. Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS 39216, USA. wwoolverton@psychiatry.umsmed.edu
Abstract
RATIONALE: Although a delay between behavior and reinforcer has been shown to weaken behavior, little is known about the effects of delay on drug choice. OBJECTIVES: The present study examined effects of delay between lever press and reinforcer presentation on the choice between a drug and non-drug reinforcer and between different drug doses. MATERIALS AND METHODS: Monkeys (n=4) were allowed to choose 32 times/day between cocaine and four food pellets. The delay between lever press and a preferred dose of cocaine (0.05 mg/kg/injection) was increased systematically from 0 to 240 s, while the delay to food remained at 0 s. A second group of monkeys (n=4) was allowed to choose between 0.05 mg/kg/injection and a lower dose of cocaine (0.025 mg/kg/injection). Next, a delay that resulted in less than 20% choice of 0.05 mg/kg/injection cocaine was selected and delay to the alternative was varied. RESULTS: Results were similar across groups. The choice of 0.05 mg/kg/injection approximated 100% at 0 delay and decreased to near 0 as delay increased. As the delay to alternative was subsequently increased from 0 to 240 s, choice of 0.05 mg/kg/injection increased, though full cocaine choice was not generally restored. The delay estimated to maintain 50% choice (indifference point) was lower for the cocaine-food choice (mean=64 s) than for the cocaine-cocaine choice (mean=207 s). CONCLUSIONS: This experiment demonstrates that the choice between cocaine and a non-drug or drug alternative can be modified by increasing the interval between behavior and drug injection. Overall, the results are consistent with a temporal discounting model of drug choice.
RATIONALE: Although a delay between behavior and reinforcer has been shown to weaken behavior, little is known about the effects of delay on drug choice. OBJECTIVES: The present study examined effects of delay between lever press and reinforcer presentation on the choice between a drug and non-drug reinforcer and between different drug doses. MATERIALS AND METHODS: Monkeys (n=4) were allowed to choose 32 times/day between cocaine and four food pellets. The delay between lever press and a preferred dose of cocaine (0.05 mg/kg/injection) was increased systematically from 0 to 240 s, while the delay to food remained at 0 s. A second group of monkeys (n=4) was allowed to choose between 0.05 mg/kg/injection and a lower dose of cocaine (0.025 mg/kg/injection). Next, a delay that resulted in less than 20% choice of 0.05 mg/kg/injection cocaine was selected and delay to the alternative was varied. RESULTS: Results were similar across groups. The choice of 0.05 mg/kg/injection approximated 100% at 0 delay and decreased to near 0 as delay increased. As the delay to alternative was subsequently increased from 0 to 240 s, choice of 0.05 mg/kg/injection increased, though full cocaine choice was not generally restored. The delay estimated to maintain 50% choice (indifference point) was lower for the cocaine-food choice (mean=64 s) than for the cocaine-cocaine choice (mean=207 s). CONCLUSIONS: This experiment demonstrates that the choice between cocaine and a non-drug or drug alternative can be modified by increasing the interval between behavior and drug injection. Overall, the results are consistent with a temporal discounting model of drug choice.
Authors: Joshua A Lile; Zhixia Wang; William L Woolverton; Jessica E France; Timothy C Gregg; Huw M L Davies; Michael A Nader Journal: J Pharmacol Exp Ther Date: 2003-09-03 Impact factor: 4.030
Authors: Sally L Huskinson; William L Woolverton; Leonard Green; Joel Myerson; Kevin B Freeman Journal: Exp Clin Psychopharmacol Date: 2015-05-04 Impact factor: 3.157
Authors: Leigh V Panlilio; Maria E Secci; Charles W Schindler; Charles W Bradberry Journal: Psychopharmacology (Berl) Date: 2017-09-04 Impact factor: 4.530