The Neural Basis of Executive Control of Internally-Directed Attention

描述（由申请人提供）：内部心理的执行控制（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。不能适当地增强或抑制对内部信息的注意是健康的年轻人和老年人注意力缺失和记忆失败的基础，也是阿尔茨海默病认知功能障碍的标志。尽管其极为重要，但内部心理执行控制的神经基础仍然缺乏特征，这是本建议的主要目标。在一系列的三个主要实验中，我们的目标是1)检查大脑“默认网络”的解剖结构和功能，一个被认为在内部心理中起主要作用的大脑系统；2)研究持续和短暂的自上而下控制内部心理与外部注意分开的神经基础；3)检查促进外部和内部（内省）注意模式之间快速切换的神经机制。首先将进行功能性磁共振成像（fMRI）元分析，以检查默认网络与几种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fMRI实验将操纵控制需求（简单与困难试验）和任务相关信息的性质（外部与内部试验），以检验类似的前额叶机制是否会使人们对内省和外部信息的注意力产生偏倚。最后，一个单独的实验将检验在外部和内省模式之间快速切换的行为特征，以及支持这种能力的分层神经机制。将在脑域内快速切换（即在性质相似的不同任务之间切换）中发挥作用的脑区域与在脑域之间快速切换（即在内部和外部任务之间切换）中起作用的脑区域进行比较。对内部心理执行控制的神经机制的了解将为年轻人成功和不成功行为的原因提供额外的见解，将有助于解释老年和AD中注意力分散和记忆障碍的机制，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. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to understand how humans regulate their internal thought processes. Different situations require either enhancement or suppression of internal thought (i.e. taking an exam or driving in a busy city, respectively), yet it remains to be understood these processes are controlled. Knowledge of these mechanisms would provide numerous benefits to older adults by facilitating cognitive training therapies that may reduce distractibility and improve memory over the course of one's lifespan.