Neuroanatomic Change and Attention Dynamics in Aging

本研究的总体目标是研究大脑结构变化与健康老年人注意力缺陷的关系。注意资源的分配和再分配速度影响感觉加工和行为反应的速度，这两者都随着年龄的增长而减慢。许多大脑区域被认为对空间注意力功能很重要，包括前额叶和顶叶皮层，丘脑，以及最近的小脑，事实上，据报道显示出与年龄相关的变化。我们建议使用结构和功能成像方法来检查这些皮层和皮层下区域，特别是小脑的结构变化和随后的功能低下是否可能是老年人注意力缺陷的基础。具体而言，我们提出：1)在横断面样本中识别健康衰老过程中发生的大脑结构变化；2)识别与注意力转移或定向相关的衰老过程中的行为和脑电图变化；3)验证年龄相关的后小脑损失可能同时影响前注意定向系统和后空间注意映射系统的假设。这些大脑网络效率的降低将导致注意力转移和定向的减慢，以及脑电生理动力学的相关变化。我们将研究120名年龄在21-85岁之间的男性和女性。所有受试者将接受：(1)神经心理学评估；(2)磁共振成像，定量皮质和皮质下区域的灰质、白质和脑脊液，以及颅内间隙的高信号；(3)注意转移任务，旨在分离与感觉、运动和注意过程相关的电生理和血流动力学活动。在这些任务中记录的行为，事件相关电位（ERP）和功能磁成像（fMRI）数据将与神经解剖学结果进行比较，以解决我们的研究假设。基于独立分量分析的新分析技术将使我们能够识别整个大脑中相关的fMRI信号变化，以及来自ERP数据的连贯脑电图的重叠模式。所提出的实验将提供关于动态注意力缺陷的神经学基础的趋同证据。这些数据还将提供方法以及神经解剖学测量的基线数据集，可用于未来的临床研究。

The overall goal of this research is to examine the association of brain structural changes with attentional deficits in healthy aging. The speed with which attentional resources can be allocated and re-allocated affects the speed of sensory processing and behavioral responding, both of which are slowed with aging. A number of the brain regions that have been identified as important to spatial attentional function, including prefrontal and parietal cortex, the thalamus, and most recently the cerebellum, have, in fact, been reported to show age-related change. We propose to use structural and functional imaging methods to examine whether structural changes and subsequent functional inefficiency in these cortical and subcortical regions, particularly the cerebellum, may underlie attention deficits in aging. Specifically, we propose 1) to identify brain structural changes occurring with healthy aging in cross-sectional samples, 2) to identify behavioral and EEG changes in aging associated with shifting or orienting of attention, and 3) to test the hypothesis that age-related loss in the posterior cerebellum may affect both an anterior attention orienting system, and a posterior spatial attention mapping system. Reduced efficiency in these brain networks would result in slowed attentional shifting and orienting, and associated changes in brain electrophysiological dynamics. We will study 120 males and females aged 21-85. All subjects will receive: (1) neuropsychological evaluation; (2) MR imaging with quantification of gray and white matter and CSF in cortical and subcortical regions of interest, and hyperintensities in intracranial space; (3) attention shift tasks designed to allow separation of electrophysiological and hemodynamic activities linked to sensory, motor, and attentional processes. Behavioral, event-related potential (ERP), and functional magnetic imaging (fMRI) data recorded during these tasks will be compared with neuroanatomic results to address our research hypotheses. New analytic techniques based on Independent Component Analysis will allow us to identify both correlated fMRI signal changes throughout the brain, and overlapping patterns of coherent EEG from ERP data. The proposed experiments will yield convergent evidence concerning the neurologic bases of dynamic attention deficits in aging. These data will also provide methods as well as a baseline dataset of neuroanatomic measures that could be used in future clinical studies.