Neuroimaging of Executive Processing

描述（由申请人提供）：执行过程有助于灵活的，自上而下的控制人类行为。包括前额叶皮层（PFC），前扣带皮层和顶叶皮层在内的大脑区域网络被认为是执行处理的中心。神经影像学和病变研究表明，这些区域在基于背景的行为选择或增强中发挥作用。本提案中详细介绍的实验将使用功能性磁共振成像（fMRI）来研究反应选择、反馈和奖励评估以及行为目标导向控制的神经机制。这项建议有三个具体目标。首先，它旨在阐明背外侧PFC（dlPFC）在行为控制中的作用，以测试的假设，即执行功能增强组的刺激反应的突发事件，而不是响应本身。所提出的实验操纵的信息量，每个刺激序列有助于学习决策规则或准备所需的响应。第二，研究了腹内侧前额叶皮层（vmPFC）在反应和奖励之间的偶然性增强中的作用。建议的实验操纵奖励期望与不同的刺激，并在不同的时间点的反应，以测试的假设，vmPFC支持奖励-反应链接的不确定性的决议。第三，通过研究奖励不确定性对决策过程的影响，探讨了前额叶系统之间的相互作用。有些刺激与未来奖励的不确定性有关，而另一些则与某些结果有关。实验测试的假设，增加活动的vmPFC奖励系统的结果减少活动的dlPFC控制系统。该研究计划将对人类执行过程的理解产生重大影响，包括选择，决策和工作记忆组件。更好地理解这些过程将导致进一步改善以执行功能或行为选择障碍为特征的神经和精神疾病的临床补救（例如，额叶损伤、精神分裂症、帕金森病）。

DESCRIPTION (provided by applicant): Executive processes facilitate the flexible, top-down control of human behavior. A network of brain regions including prefrontal cortex (PFC), anterior cingulate cortex, and parietal cortex is thought to be central for executive processing. Neuroimaging and lesion studies have suggested that these regions play a role in selection or potentiation of behavior based upon context. The experiments detailed in this proposal will use functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms of response selection, evaluation of feedback and rewards, and the goal-directed control of behavior. This proposal has three specific aims. First, it seeks to elucidate the role of dorsolateral PFC (dlPFC) in behavioral control, to test the hypothesis that executive functions potentiate sets of stimulus-response contingencies rather than responses themselves. The proposed experiments manipulate the amount of information each stimulus in a sequence contributes either to learning a decision rule or to preparing a needed response. Second, it investigates the role of ventromedial PFC (vmPFC) in the potentiation of contingencies between responses and rewards. The proposed experiments manipulate the reward expectation associated with different stimuli and with responses at different points in time, to test the hypothesis that vmPFC supports the resolution of uncertainty about reward-response links. Third, it investigates the interaction between prefrontal systems by examining the influence of reward uncertainty upon decision processes. Some stimuli are associated with uncertainty in future rewards, while others are associated with certain outcomes. The experiments test the hypothesis that increasing activity in vmPFC reward systems results in decreased activity in dlPFC control systems. The proposed research program will have a significant impact upon the understanding of human executive processing, including selection, decision, and working memory components. A better understanding of these processes will lead to further improvements in clinical remediation of neurological and psychiatric disorders characterized by impairments in executive function or behavioral selection (e.g., frontal lobe damage, schizophrenia, Parkinson's disease).