Imaging the effects of expectations on feedback-based learning

描述（申请人提供）：药物成瘾的发展取决于药物激活大脑“奖励回路”的能力，该回路的作用是加强吸毒行为。为了深入了解这个过程，重要的是要了解健康大脑中强化学习的神经过程。纹状体和眶额皮层（OFC）是大脑奖赏回路中的两个关键区域，不仅会被滥用药物激活，还会被其他奖励激活，如食物或金钱。即使是没有外在价值的奖励，例如在困难的任务上表明正确答案的积极反馈，也会参与这个系统，促进从与表现相关的反馈中学习。然而，目前尚不清楚诸如成功预期等情境因素如何影响这些大脑区域的处理，以及从反馈中学习的数量。因此，拟议的研究使用基于反馈的学习作为模型系统，以了解期望如何影响行为预测者的神经处理。参与者将在功能性磁共振成像（fMRI）数据采集过程中执行基于反馈的学习任务。实验一考察了抽象标签“难”和“容易”对任务难度预期和绩效反馈的神经加工的影响。实验2通过与同伴表现的比较来操纵难度期望。预测试的错误结果将向参与者表明他们的表现高于或低于平均水平。然后，参与者将执行基于反馈的学习任务，同时用fMRI扫描他们的大脑，以检查能力标签对纹状体和OFC中反馈相关信号的影响。这些实验将促进启动一个大脑成像研究计划的神经机制参与动机行为。这样的研究可能会深入了解行为如何被激励向生产性激励，如成就，并远离有害的激励，如非法药物。 公共卫生相关性：拟议的实验研究的背景影响的大脑机制参与学习的行为模仿者。这些相同的机制也参与了药物成瘾的发展，因此研究结果可能表明药物作为行为激励的能力可以通过动机背景的变化而改变的原则。

DESCRIPTION (provided by applicant): The development of drug addiction depends on the ability of drugs to activate the brain's "reward circuit," which acts to reinforce the drug-taking behavior. In order to gain insight into this process, it is important to understand the neural processes underlying reinforcement learning in the healthy brain. The striatum and orbitofrontal cortex (OFC), two key regions in the brain's reward circuit, are activated not only by drugs of abuse, but also by other rewards, such as food or money. Even rewards with no extrinsic value, such as positive feedback indicating a correct answer on a difficult task, engage this system, promoting learning from the performance-related feedback. It remains unclear, however, how contextual factors such as expectations of success influence processing in these brain regions, and in turn, the amount learned from feedback. Therefore, the proposed research uses feedback-based learning as a model system for understanding how expectations influence the neural processing of behavioral reinforcers. Participants will perform a feedback- based learning task during acquisition of functional magnetic resonance imaging (fMRI) data. Experiment 1 investigates how the abstract labels, "hard" and "easy," affect expectations of task difficulty and the neural processing of performance-related feedback. Experiment 2 manipulates difficulty expectations through a comparison with peer performance. False results from a pre-test will indicate to the participants that their performance is above or below average. The participants will then perform the feedback-based learning task as their brains are scanned with fMRI, allowing the effect of the ability labels on feedback-related signals in the striatum and OFC to be examined. These experiments will foster the initiation of a brain imaging research program on the neural mechanisms involved in motivated behavior. Such research may yield insights into how behavior could be motivated toward productive incentives, such as achievement, and away from harmful incentives, such as illicit drugs. PUBLIC HEALTH RELEVANCE: The proposed experiments examine contextual influences on the brain mechanisms involved in learning from behavioral reinforcers. These same mechanisms are involved in the development of drug addiction, so the research findings may suggest principles by which the ability of drugs to act as behavioral incentives could be altered through changes in motivational context.