The Neural Basis of Executive Control of Internally-Directed Attention

描述(由申请人提供)：对内部心理状态的执行控制(即反思一个人的过去，思考一个人的未来，或参与其他内省的认知过程)是成功行为的关键。未能适当地加强或抑制对内部信息的注意力，构成了健康年轻人和老年人注意力缺失和记忆衰竭的基础，并代表了阿尔茨海默病认知功能障碍的标志。尽管执行控制内部心理状态的神经基础极其重要，但它的特点仍然很差，是本提案的主要目标。在一系列的三个主要实验中，我们的目标是：1)研究大脑“默认网络”的解剖和功能，这是一个被认为在内部心理状态中起主要作用的大脑系统；2)研究内部心理状态持续和短暂的自上而下控制与外部注意力分开的神经基础；3)研究促进注意的外部和内部(内省)模式快速切换的神经机制。首先将进行功能磁共振成像(FMRI)荟萃分析，以检查默认网络和几个不同的内省任务之间的重叠，以深入了解网络的总体功能。接下来，一项操纵控制需求(简单试验与困难试验)和任务相关信息的性质(外部试验与内部试验)的fMRI实验将检验类似的前额叶机制是否会使注意力偏向内省和外部信息。最后，一个单独的实验将检验在外部和内省注意模式之间快速切换的行为特征，以及支持这一能力的分级神经机制。在域内快速切换(即，在性质相似的不同任务之间切换)起作用的大脑区域将与那些在域间快速切换(即，在内部和外部任务之间切换)的区域进行比较。了解支配内部心理状态的执行控制的神经机制将提供对年轻人成功和不成功行为原因的进一步洞察，将有助于解释晚期衰老和AD患者注意力分散和记忆失败的机制，并将促进适用于这些人群的认知训练和康复范例的发展。

DESCRIPTION (provided by applicant): Executive control of internal mentation (i.e. reflecting upon one's past, thinking about one's future, or engaging in other introspective cognitive processes) is critical for successful behavior. Failures to appropriately enhance or suppress attention to internal information form the basis of attentional lapses and memory failures in healthy young and old adults, and represent a hallmark of cognitive dysfunction in Alzheimer's disease. Despite its utmost significance, the neural basis of executive control of internal mentation remains poorly characterized and represents the primary objective of the present proposal. In a series of three main experiments, we aim to 1) examine the anatomy and function of the brain's "default network," a brain system thought to play a major role in internal mentation, 2) investigate the neural underpinnings of sustained and transient top-down control of internal mentation separately from external attention and 3) examine the neural mechanisms facilitating rapid switching between external and internal (introspective) modes of attention. A functional magnetic resonance imaging (fMRI) meta-analysis will be first conducted to examine the overlap between the default network and several different introspective tasks to gain insight into the network's overarching function. Next, an fMRI experiment that manipulates demand for control (easy vs. hard trials) and the nature of the task-relevant information (external vs. internal trials) will examine whether similar prefrontal mechanisms bias attention to both introspective and external information. Finally, a separate experiment will examine the behavioral signatures of rapid switching between external and introspective modes of attention as well as the hierarchical neural mechanisms that support this ability. Brain regions that play a role in rapid switching within domains (i.e. switching between different tasks of a similar nature) will be compared to those regions that underlie rapid switching between domains (i.e. switching between internal and external tasks). Knowledge of the neural mechanisms that govern executive control of internal mentation will provide additional insight into the causes of successful and unsuccessful behavior in young adults, will help explain the mechanisms that underlie distractibility and memory failures in advanced aging and AD, and will facilitate the development of cognitive training and rehabilitation paradigms applicable to these populations.