Pierce-Messick Zachary, Shipman Megan L, Desilets Gabrielle L, Corbit Laura H
Department of Psychology, University of Toronto, Toronto, Ontario, Canada.
Nat Protoc. 2025 Feb;20(2):518-538. doi: 10.1038/s41596-024-01054-3. Epub 2024 Oct 23.
Goal-directed behaviors allow animals to act to satisfy needs and desires. The outcome devaluation task is an effective method for identifying goal-directed behaviors and distinguishing these from other types of behavior. Rats can be trained to lever-press for one or multiple distinct food rewards. During testing, the previously earned food-or a control food for comparison-is devalued by allowing the animal to freely feed on it until they are sated before testing lever-press performance under extinction conditions (no rewards are delivered). Behavior that adapts to reflect the new value of the outcome is considered goal-directed, whereas behavior that continues as in previous training despite the change in outcome value, is not. As more research groups have used this task, variability in the procedures used has increased. Here, we provide a reliable procedure for conducting the outcome devaluation task with appropriate controls. We describe the most common variants of the task and control conditions and discuss troubleshooting measures such as outcome pre-exposure, habituation to pre-feeding chambers and attention to animals' hunger levels. The method outlined can be executed in 2 weeks including training (8 d) and testing (1-4 d) by researchers who are familiar with performing behavioral tasks in laboratory rodents, although longer training may be considered for those who are interested in observing habitual control of behavior. This protocol should facilitate the comparison of results from different studies and laboratories, while allowing flexibility in the application of the outcome devaluation task to different research questions.
目标导向行为使动物能够采取行动来满足需求和欲望。结果贬值任务是识别目标导向行为并将其与其他类型行为区分开来的有效方法。大鼠可以被训练通过按压杠杆来获取一种或多种不同的食物奖励。在测试期间，通过让动物自由进食先前获得的食物或用于比较的对照食物，直到它们吃饱，然后在消退条件下（不给奖励）测试杠杆按压表现，从而使先前获得的食物贬值。适应以反映结果新价值的行为被认为是目标导向的，而尽管结果价值发生了变化，但仍像先前训练那样持续的行为则不是。随着越来越多的研究小组使用这个任务，所采用的程序的变异性增加了。在这里，我们提供了一个可靠的程序，用于在有适当对照的情况下进行结果贬值任务。我们描述了该任务和对照条件的最常见变体，并讨论了诸如结果预暴露、对预喂饲室的习惯化以及关注动物饥饿水平等故障排除措施。熟悉在实验室啮齿动物中进行行为任务的研究人员可以在大约2周内（包括训练约8天和测试1 - 4天）执行所概述的方法，不过对于那些有兴趣观察行为习惯控制的人可能需要考虑更长时间的训练。该方案应有助于不同研究和实验室结果的比较，同时允许在将结果贬值任务应用于不同研究问题时具有灵活性。
