Top-down modulation and interactions between perceptual and reflective processess

描述(由申请人提供)：健康和病理性衰老都会导致一定程度的认知和神经衰退。执行功能似乎特别受年龄的影响(Hasher&Zack，1988)。传统上，执行功能与前额叶皮质(PFC)联系最密切，但最近的研究表明，PFC和感觉关联皮质之间的相互作用在执行过程中也发挥着重要作用。这项建议的广泛目标是进一步阐明自上而下的执行过程如何影响类别选择性纹外皮质(CSE)的活动，首先在健康的年轻人中建立范例，然后用它们来研究这些过程在老年人中的下降。具体目标#1：研究自上而下的过程抑制和增强年轻人的知觉和表征的机制。两项功能磁共振成像(FMRI)研究将检验知觉和反射性注意过程如何抑制CSE皮质与非注意刺激相关的活动。这一目标与国家情报机构的使命特别相关，因为最近的研究表明，老年人自上而下的抑制存在特定的缺陷(Gazzaley等人，2005年)，但对这种抑制的具体机制，特别是对反思注意的具体机制，人们知之甚少。具体目标2：分析由反射加工引起的CSE皮层活动的信息量。人们认为CSE皮层中的活动是由反射过程(如工作记忆、心理意象)引起的，代表了关于头脑中特定项目的信息，但文献中对此的证据相对较少。这项fMRI实验的目的是解码大脑中脑脊束核皮质在心理想象过程中的项目信息。未来的研究将考察年轻人和老年人的信息表征有何不同。这项研究旨在加深我们对人类大脑如何执行高级认知操作的了解，这些操作统称为“执行功能”，众所周知，这些操作特别容易受到健康和病理性衰老中出现的认知衰退的影响。该研究计划包括三个大脑成像实验，旨在确定几个简单的执行操作如何影响大脑中涉及处理视觉信息的区域的活动。最终目标是比较年轻人和老年人在执行不同类型执行功能时的大脑活动，以便研究这些过程是如何随着年龄的增长而恶化的。

DESCRIPTION (provided by applicant): Both healthy and pathological aging entail some degree of cognitive and neural decline. Executive functions appear to be particularly affected by aging (Hasher & Zacks, 1988). Executive function has traditionally been associated most strongly with the prefrontal cortex (PFC), but recent research has shown that interactions between PFC and sensory association cortex also play an important role in executive processes. The broad objective of this proposal is to shed further light on how top-down executive processes affect activity in category-selective extrastriate (CSE) cortex, developing paradigms first in healthy young adults and then using them to study these processes' decline in older adults. Specific Aim #1: Examine mechanisms by which top-down processes suppress as well as enhance percepts and representations in young adults. Two functional magnetic resonance imaging (fMRI) studies will examine how perceptual and reflective attention processes act to suppress activity in CSE cortex related to non-attended stimuli. This aim has particular relevance to the mission of the NIA as recent studies have shown specific deficits in top-down suppression in older adults (Gazzaley et al., 2005), but relatively little is known about the specific mechanisms underlying such suppression, especially for reflective attention. Specific Aim #2: Analyze the information content of activity in CSE cortex caused by reflective processing. It is thought that activity in CSE cortex induced by reflective processes (e.g., working memory, mental imagery) represents information about the specific item in mind, but there is relatively little evidence for this in the literature. This fMRI experiment is aimed at decoding item information in CSE cortex during mental imagery. Future studies will then examine how information representation differs in young and older adults. This research is designed to further our knowledge of how the human brain performs high-level cognitive operations, collectively called "executive functions," which are known to be particularly susceptible to the cognitive decline that occurs in both healthy and pathological aging. The research plan includes three brain imaging experiments aimed at determining how several simple executive operations affect activity in areas of the brain involved in processing visual information. The ultimate goal is to compare the brain activity of younger adults to older adults while performing different types of executive functions in order to study how these processes deteriorate as people age.