Department of Psychological Science, Northern Kentucky University.
Department of Psychological and Brain Sciences, University of Louisville.
Exp Clin Psychopharmacol. 2020 Apr;28(2):181-195. doi: 10.1037/pha0000300. Epub 2019 May 23.
Risky choice is the tendency to choose a large, uncertain reward over a small, certain reward, and is typically measured with probability discounting, in which the probability of obtaining the large reinforcer decreases across blocks of trials. One caveat to traditional procedures is that independent schedules are used, in which subjects can show exclusive preference for one alternative relative to the other. For example, some rats show exclusive preference for the small, certain reinforcer as soon as delivery of the large reinforcer becomes probabilistic. Therefore, determining if a drug increases risk aversion (i.e., decreases responding for the probabilistic alternative) is difficult (due to floor effects). The overall goal of this experiment was to use a concurrent-chains procedure that incorporated a dependent schedule during the initial link, thus preventing animals from showing exclusive preference for one alternative relative to the other. To determine how pharmacological manipulations alter performance in this task, male Sprague-Dawley rats (n = 8) received injections of amphetamine (0, 0.25, 0.5, 1.0 mg/kg), methylphenidate (0, 0.3, 1.0, 3.0 mg/kg), and methamphetamine (0, 0.5, 1.0, 2.0 mg/kg). Amphetamine (0.25 mg/kg) and methylphenidate (3.0 mg/kg) selectively increased risky choice, whereas higher doses of amphetamine (0.5 and 1.0 kg/mg) and each dose of methamphetamine impaired stimulus control (i.e., flattened the discounting function). These results show that dependent schedules can be used to measure risk-taking behavior and that psychostimulants promote suboptimal choice when this schedule is used. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
风险选择是指倾向于选择大的、不确定的奖励而不是小的、确定的奖励，通常用概率折扣来衡量，即在获得大奖励的概率在试验块中降低。传统程序的一个警告是，使用独立的时间表，在这种时间表中，相对于另一个，主体可以表现出对一个选择的唯一偏好。例如，一些老鼠一旦大奖励的传递变得不确定，就会立即对小的、确定的奖励表现出唯一的偏好。因此，确定一种药物是否会增加回避风险（即减少对概率性替代物的反应）是困难的（由于地板效应）。本实验的总体目标是使用一种包含依赖时间表的同时链程序，从而防止动物相对于另一个对一个选择表现出唯一偏好。为了确定药理学操作如何改变该任务中的表现，雄性 Sprague-Dawley 大鼠（n = 8）接受了安非他命（0、0.25、0.5、1.0 mg/kg）、哌甲酯（0、0.3、1.0、3.0 mg/kg）和甲基苯丙胺（0、0.5、1.0、2.0 mg/kg）的注射。安非他命（0.25 mg/kg）和哌甲酯（3.0 mg/kg）选择性地增加了风险选择，而较高剂量的安非他命（0.5 和 1.0 mg/kg）和每个剂量的甲基苯丙胺损害了刺激控制（即，使折扣函数变平）。这些结果表明，依赖时间表可用于测量冒险行为，并且当使用这种时间表时，精神兴奋剂会促进次优选择。（PsycInfo 数据库记录（c）2020 APA，保留所有权利）。
