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。

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.