Behavioral and Neural Representations of Subjective Effort Cost

一项任务给人的努力感是人类决策形成动机的一个组成部分。如果一项任务感觉非常费力，我们可能不愿意完成它，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。尽管这些感知对决策很重要，但主观努力评估的行为和神经机制尚未得到很好的理解。此外，美国国家精神卫生研究院（NIMH）研究领域标准（RDoC）已经确定“努力评估/工作意愿”作为理解精神障碍患者动机表现缺陷的关键子结构。本提案的目标是了解身体和认知努力的主观评价机制，以及这些表征背后的共同和独特的系统。为此，我们将结合健康人类参与者的实验、行为计算模型和功能磁共振成像（fMRI）。在目标1中，我们将确定共同和独特的身体和认知努力评估机制。我们将计算模拟参与者对身体和认知努力的主观评价，以测试对这些不同类型的努力的主观偏好是否有相似之处。我们将使用基于模型的功能磁共振成像来检查编码身体和认知努力的主观评价的常见和独特的大脑区域，以及包含这些偏好以激励努力参与的大脑区域网络。在目标2中，我们将研究身体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消耗使参与者感到疲劳，并检查疲劳状态如何影响对体力和认知努力的主观评价；以及大脑评估网络中的相关信号。在Aim 3中，我们将探讨动机状态如何调节决定以发挥身体和认知努力。为了调节参与者的动机状态，我们将把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。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离开来，以便了解这些过程如何相互作用以产生动机的身体和认知参与。总之，我们提出的研究将通过剖析负责身体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，以帮助动机的研究、分类和治疗。

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.