Department of Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, Mail Code 7764, San Antonio, Texas 78229, USA.
J Exp Anal Behav. 2011 Mar;95(2):163-74. doi: 10.1901/jeab.2011.95-163.
Delay to delivery of a reinforcer can decrease responding for that reinforcer and increase responding for smaller reinforcers that are available concurrently and delivered without delay; acute administration of drugs can alter responding for large, delayed reinforcers, although the impact of chronic treatment on delay discounting is not well understood. In this experiment, the effects of repeated administration of the benzodiazepine flunitrazepam were studied in 6 pigeons responding on one key to receive food that was delivered immediately and on a second key to receive a larger amount of food that was delivered following delays which increased across a single session. Pigeons responded predominantly for the large reinforcer when there were no delays and when delays were short; however, as delays increased, responding for the large reinforcer decreased. Acutely, flunitrazepam (0.32, 1.0 and 3.2 mg/kg) dose-dependently increased responding for the large reinforcer, shifting the discounting curve rightward and upward. Repeated administration of flunitrazepam (0.32, 1.0 and 3.2 mg/kg, each for six sessions, separated by one session during which vehicle was administered) did not markedly alter its effects on responding for the large reinforcer, indicating that the development of tolerance to this effect of flunitrazepam is modest under these conditions.
延迟强化物的传递会减少对该强化物的反应，并增加对同时提供且即时传递的较小强化物的反应；急性给予药物会改变对大延迟强化物的反应，尽管慢性治疗对延迟折扣的影响尚不清楚。在这项实验中，研究了苯二氮䓬类药物氟硝西泮在 6 只鸽子身上的重复给药的影响，这些鸽子通过按一个键来接收即时传递的食物，通过按另一个键来接收更大数量的食物，而后者的传递是在整个单一的会议期间延迟增加的。当没有延迟且延迟较短时，鸽子主要对大强化物做出反应；然而，随着延迟的增加，对大强化物的反应减少。急性给予氟硝西泮（0.32、1.0 和 3.2mg/kg）剂量依赖性地增加了对大强化物的反应，使折扣曲线向右和向上移动。重复给予氟硝西泮（0.32、1.0 和 3.2mg/kg，每次 6 个疗程，每个疗程之间间隔一个疗程给予载体）对大强化物的反应没有明显改变，表明在这些条件下，氟硝西泮对这种作用的耐受性发展适度。
