Behavioral and Neural Representations of Subjective Effort Cost

一项任务感觉有多费力，是人类决策中不可或缺的一个方面，它塑造了动力。如果一项任务感觉非常费力，我们可能不愿意完成所需的工作，而如果一项任务感觉不那么费力，我们可能更有可能坚持下去。尽管这些认知对决策很重要，但主观努力评估的行为和神经机制还没有被很好地理解。此外，美国国立精神卫生研究院(NIMH)的研究领域标准(RDoC)已将“努力价值/工作意愿”确定为理解精神障碍患者动机表现缺陷的一个关键子结构。这项建议的目标是理解体力和认知努力的主观评估机制，以及这些表征所依据的共同和独特的系统。为此，我们将使用健康人体参与者的实验、行为的计算模型和功能磁共振成像(FMRI)的组合。在目标1中，我们将确定共同的和不同的体力和认知努力的评估机制。我们将对参与者对体力和认知努力的主观评价进行计算建模，以测试这些不同类型的努力在主观偏好上是否有相似之处。我们将使用基于模型的功能磁共振成像来研究共同和独特的大脑区域，这些区域编码了对身体和认知努力的主观评估，以及包含这些偏好的大脑区域网络，以激励努力投入。在目标2中，我们将研究身体疲劳和认知疲劳影响努力评估的行为和神经机制。我们将通过持续的体力或认知努力使参与者疲惫，并研究疲惫状态如何影响对体力和认知努力的主观评估；以及大脑评估网络中的相关信号。在目标3中，我们将探索动机状态如何调节决策，以施加身体和认知努力。我们会将身体和认知努力的选择与动机线索(即以前预测奖励的线索)配对，以调节参与者的动机状态。这种操作将使我们能够在行为和神经上将动机与努力评估分开，以便理解这些过程如何相互作用，从而产生动机的身体和认知投入。总而言之，我们提出的研究将通过剖析负责体力和认知努力评估的行为和神经机制，对决策领域产生广泛的影响。从长远来看，这些研究可能会揭示新的行为和神经标记物，以帮助研究、分类和治疗运动障碍。

How effortful a task feels is an integral aspect of human decision-making that shapes motivation. If a task feels very effortful we may be unwilling to perform the work required, whereas if a task feels less effortful we may be more likely to persevere. Despite the importance of these perceptions for decision-making, the behavioral and neural mechanisms of subjective effort valuation are not well understood. Furthermore, the National Institutes of Mental Health (NIMH) Research Domain Criteria (RDoC) has identified “Effort Valuation / Willingness to Work” as a key subconstruct for understanding deficits in motivated performance in mental disorders. The goal of this proposal is to understand the mechanisms of subjective valuation of physical and cognitive effort, and the common and distinct systems that underlie these representations. To this end, we will use a combination of experiments in healthy human participants, computational modeling of behavior, and functional magnetic resonance imaging (fMRI). In Aim 1 we will identify common and distinct physical and cognitive effort valuation mechanisms. We will computationally model participants’ subjective valuation of physical and cognitive effort to test if there are similarities in subjective preferences for these different types of effort. We will use model-based fMRI to examine the common and distinct brain regions that encode the subjective valuation of physical and cognitive effort, and the network of brain regions that incorporate such preferences to motivate effortful engagement. In Aim 2 we will investigate the behavioral and neural mechanisms by which physical and cognitive fatigue effect effort valuation. We will fatigue participants with sustained physical or cognitive exertion and examine how being in a fatigued state influences subjective valuation of physical and cognitive effort; and associated signals in the brain’s valuation network. In Aim 3 we will explore how motivational state modulates decisions to exert physical and cognitive effort. We will pair choices for physical and cognitive effort with motivational cues (i.e., cues that formerly predicted reward) in order to modulate participants’ motivational state. This manipulation will allow us to behaviorally and neurally dissociate motivation from effort valuation in order to understand how these processes interact to give rise to motivated physical and cognitive engagement. In sum, our proposed studies will have a broad impact on the field of decision-making by dissecting the behavioral and neural mechanisms responsible for physical and cognitive effort valuation. In the long term, these studies may reveal novel behavioral and neural markers to aid in the study, classification, and treatment of amotivation.