Functional MRI of Aging: Biophysical Characterization

描述（由申请人提供）：近年来，许多使用功能性MRI（fMRI）的研究显示，老年受试者（> 50岁）和年轻受试者（21-40岁）在执行许多不同的感觉运动和认知任务时，激活模式存在显著差异。已经得出结论，观察到的对比度是由于老年受试者中神经元活动的差异。然而，早期的假设，即正常老化涉及神经元的广泛损失已被修改，因为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和衰老过程中是稳定的。除了对神经元功能的直接影响外，已知老年人中导致脑血管反应性的因素也会改变，这可能会引起血流动力学反应的改变。由于使用功能磁共振成像观察到的信号可以调制的血液动力学和氧合的变化所导致的神经元的变化，这两个因素必须分开，以获得更好地了解年龄相关的变化，激活模式获得使用功能磁共振成像。目前提出的项目旨在结合联合收割机基础科学，工程和计算问题，以具体阐明机制（神经元与血管），导致老年受试者与年轻受试者相比，改变了大脑激活。从非侵入性技术（fMRI）获得的结果将提供测量许多相关生理因素的方法，并从生物病理学角度描述它们，以了解人类大脑功能随年龄增长的变化。所开发的方法和技术也可用于研究两个或多个不同的群体。 公共卫生相关性： 目前的项目将有助于确定生物物理方面的老化使用非侵入性功能磁共振成像（fMRI）。由于纵向研究是非常重要的，通过跟踪个人的不同阶段，他们的寿命，功能磁共振成像技术将成为至关重要的，以获得有价值的生物标志物的研究老化。功能磁共振成像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提出了许多警告。该项目旨在通过有效测试和量化可能调节年轻和老年受试者信号反应的神经和血液动力学成分来解决某些警告。这项研究将显着获得有关的基本性质和必要的修正功能磁共振信号的信息。这种校正对于准确确定影响认知效果和大脑功能的生命周期所有阶段的变化的进展和决定因素是必要的。

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.