Neuroimaging of Executive Processing

描述(由申请人提供)：执行过程促进了对人类行为的灵活、自上而下的控制。包括前额叶皮质(PFC)、前扣带回皮质和顶叶皮质在内的大脑区域网络被认为是执行过程的中心。神经成像和损伤研究表明，这些区域在基于背景的行为选择或增强中发挥作用。这项提议中详细介绍的实验将使用功能磁共振成像(FMRI)来研究反应选择、反馈和奖励的评估以及目标导向的行为控制的神经机制。这项提议有三个具体目标。首先，它试图阐明背外侧PFC(DlPFC)在行为控制中的作用，以检验执行功能增强刺激反应偶发集合而不是反应本身的假设。拟议的实验操纵了序列中每个刺激有助于学习决策规则或准备所需反应的信息量。其次，研究了腹内侧PFC(VmPFC)在增强反应和奖励之间的偶然性中的作用。该实验操控了不同刺激和不同时间点反应的奖赏期望，以检验vmPFC支持解决奖赏-反应环节的不确定性的假设。第三，通过考察奖励不确定性对决策过程的影响，考察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。这些实验验证了vmPFC奖励系统中活动增加会导致dlPFC控制系统中活动减少的假设。拟议的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。更好地了解这些过程将进一步改善以执行功能或行为选择障碍(如额叶损伤、精神分裂症、帕金森病)为特征的神经和精神疾病的临床治疗。

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).