Role of Fronto-Parietal Cortex in Delay Discounting

在未来不同时刻可获得的结果之间做出的选择(跨期选择)构成了日常生活中一套重要和常见的决策。人们对这样的选择的反应也是已知的，可以预测一些重要的生活结果，并可以通过实验室的延迟折扣测量来总结。了解延迟折扣背后的认知大脑过程，特别是我们抵抗直接诱惑的能力，是认知神经科学研究的一个重要领域。在过去十年中，这一领域取得了重大进展。现在已经确定，大脑奖赏区域，包括腹内侧额叶皮质(VmPFC)，编码预期奖赏的主观价值。在做出跨期选择时，前额外侧(LPFC)、额叶背内侧(DMFC)和顶叶后皮质(PPC)区域的网络也被证实。然而，这个额顶皮质网络(FPN)的作用仍然存在争议和较少的了解。目前的研究项目建立在麦克卢尔和他的同事最近所做的计算建模工作的基础上，以测试和统一延迟贴现中FPN函数的相互竞争的理论。这项工作有助于我们进一步理解与意志力和自控力的发挥有关的重要认知过程的大脑基础。我们将进行三项研究，同时使用fMRI和EEG来研究不同额区和顶区在跨期决策中的作用。在前期工作中，我们使用我们的计算模型框架证明：(1)在选择期权的价值过程中，PPC与vmPFC相互作用；(2)在行动选择过程中，价值信息积累在DMFC中。这个项目将进一步测试FPN在诱惑和认知负荷条件下的功能，以及这些操作如何影响选择结果。许多疾病，包括注意力缺乏性过敏症和药物成瘾，都与延迟打折直接相关。因此，提出的延迟折扣研究代表了一个明确的例子，其中认知神经科学方法有望直接影响和提高我们对正常和异常行为的理解。最后，决策神经科学是一个高度交叉的领域，它结合了经济学、心理学和神经科学的元素。它为直接参与该项目的不同培训级别的学生提供了一个令人兴奋的培训机会。

Choices made between outcomes available at different points in the future(intertemporal choices) constitute an important and common set of decisionsencountered in everyday life. How people respond to such choices is also knownto be predictive of a number of important life outcomes, and can be summarizedusing laboratory measures of delay discounting. Understanding the cognitivebrain processes that underlie delay discounting, and particularly our ability toresist immediate temptations, is an important area of research in cognitiveneuroscience. Significant progress has been made in this area over the pastdecade. It is now well established that brain reward areas, including theventromedial prefrontal cortex (vmPFC), encode the subjective value ofprospective rewards. It is also established that a network of regions in lateralprefrontal (lPFC), dorsomedial frontal (dmFC), and posterior parietal cortex (pPC)are engaged when making intertemporal choices. However, the role of thisfronto-parietal cortical network (FPN) remains debated and less understood. Thecurrent research project builds on recent computational modeling work done byMcClure and his colleagues to test and unify competing theories of FPN functionin delay discounting. This work promises to further our understanding of the brainbasis of important cognitive processes related to the exertion of willpower andself-control.We will conduct three studies that employ both fMRI and EEG to investigate therole of different frontal and parietal regions in intertemporal decision-making. Inpreliminary work, we have used our computation model framework todemonstrate that (1) the pPC interacts with the vmPFC during the valuing ofchoice options, and (2) value information is accumulated in the dmFC duringaction selection. This project will further test how the FPN functions underconditions of temptation and cognitive load and how these manipulationsinfluence choice outcomes. A number of disorders, including attention deficithyperactivity disorder and drug addiction, have been directly associated withdelay discounting. The proposed studies of delay discounting therefore representa clear example in which cognitive neuroscience approaches promise to directlyimpact and improve our understanding of normal and aberrant behavior. Finally,decision neuroscience is a highly interdisciplinary field that combines elements ofeconomics, psychology, and neuroscience. It offers an exciting trainingopportunity for the students at various levels of training who will be directlyinvolved in the project.