Functional MRI of Aging: Biophysical Characterization

描述(申请人提供)：近年来，许多使用功能磁共振成像(FMRI)的研究表明，在执行一些不同的感觉运动和认知任务时，老年受试者(50岁)和年轻受试者(21-40岁)的激活模式存在显著差异。结论是，观察到的对比是由于年长受试者神经元活动的差异。然而，随着越来越多的证据表明，在大脑的大多数区域，神经元的数量在整个成年期和衰老过程中是稳定的，早期关于正常衰老涉及神经元广泛丧失的假设已经被修正。除了对神经元功能的直接影响外，已知的是，在老年人中，导致脑血管反应性的因素会发生变化，可能会引起血液动力学反应的改变。由于fMRI观察到的信号可以同时受到血流动力学和由神经元变化引起的氧合变化的调制，因此必须将这两个因素分开，才能更好地理解fMRI获得的激活模式中与年龄相关的变化。目前提出的项目旨在结合基础科学、工程学和计算问题来具体阐明导致老年受试者与年轻受试者相比大脑激活发生变化的机制(神经元与血管)。从非侵入性技术(FMRI)获得的结果将为测量一些相关的生理因素并对其进行生物物理表征以了解人类大脑随年龄增长的功能提供方法。开发的方法和技术也可以用于在两个或更多不同的小组之间进行研究。 公共卫生相关性： 本项目将使用非侵入性功能磁共振成像(FMRI)来帮助确定衰老的生物物理学方面。由于纵向研究对于跟踪个体生命的不同阶段是非常重要的，fMRI技术将成为在衰老研究中获得有价值的生物标志物的关键。在确定影响年轻和老年受试者信号反应的实际生理指标时，fMRI提出了许多警告。该项目旨在通过有效地测试和量化可能调节年轻和老年受试者的信号反应的神经和血流动力学成分来解决某些警告。这项研究将显著获得有关fMRI信号的潜在性质和必要校正的信息。为了准确地确定影响认知效果和大脑功能的所有生命阶段的变化进程和决定因素，这种校正是必要的。

DESCRIPTION (provided by applicant): In the recent years, a number of studies using functional MRI (fMRI) have shown substantial differences between the activation pattern of older subjects (> 50 years of age) and younger subjects (21-40 years) while performing a number of different sensorimotor and cognitive tasks. It has been concluded that the contrast observed is due to differences in neuronal activity in the older subjects. However, early hypothesis that normal aging involves widespread loss of neurons have been revised in light of accumulating evidence that in most regions of the brain, the number of neurons is stable throughout adulthood and senescence. In addition to direct effects on neuronal function, factors contributing to cerebrovascular reactivity is known to be altered in older people that could give rise to altered hemodynamic responses. Since the signal observed using fMRI could be modulated both by hemodynamics and oxygenation changes resulting from neuronal changes, these two factors must be separated to gain a better understanding about age related changes in the activation pattern obtained using fMRI. The present project proposed intends to combine basic science, engineering, and computational issues to specifically elucidate mechanisms (neuronal vs vascular) that results in older subjects having altered brain activation in comparison to young subjects. Results obtained from the noninvasive technique (fMRI) would provide ways to measure a number of relevant physiological factors and characterize them biophysically to understand human brain function with aging. Methods and techniques developed can also be used to study between two or more different groups. PUBLIC HEALTH RELEVANCE: The present project will help determine biophysical aspects of aging using non-invasive functional Magnetic Resonance Imaging (fMRI). As longitudinal studies are very important to follow individuals through different stages of their life span, fMRI techniques would become crucial in obtaining valuable biomarkers in studies of aging. FMRI presents many caveats in determining the actual physiological indicators that influence signal response in young and old subjects. This project is designed to address certain caveats by effectively testing and quantifying the neural and hemodynamic components that may modulate signal response in young and old subjects. This study will significantly gain information regarding the underlying nature and necessary corrections in fMRI signals. Such a correction is necessary to accurately determine the progression and determinants of change across all segments of the life span that affect cognitive effects and brain function.