Vascular Dynamics in Functional MRI

项目概述自十多年前引入以来，功能磁共振成像 功能磁共振成像(FMRI)已迅速成为研究工作人脑不可或缺的工具。绝大多数人 Fmri研究利用反映血流动力学的血氧水平依赖(BOLD)信号。 对神经活动的反应。在这些研究中，粗体信号的差异通常被解释为 神经活动的差异。然而，越来越多的证据表明，基线血管状态的变化 由于药物、年龄和疾病等因素，可以显著改变脑电的幅度和形状 大胆的信号。这些因素会增加不同受试者粗体信号的可变性 实验条件和复杂的功能磁共振实验解释。此应用程序的目标是 就是确定基线血管状态的非侵入性测量是否可以解释这种变异性 在大胆的信号是由血管活性物质和衰老过程引起的。的中心假说 这一建议得到了强劲的初步数据的支持，它是对中国电力的标准化衡量标准 BOLD信号的低频分量，称为0.1赫兹频谱指数，可用于 探测基线血管状态，可以解释BOLD患者很大一部分变异性 回应。这项建议的目的是(1)评估0.1赫兹频谱指数和其他 基线血管状态的测量，以解释由以下因素引起的大胆反应的变异性 血管活性物质，以及(2)评估这些测量方法解释年龄相关变异性的能力。 大胆的回应。这些目标将通过(1)评估咖啡因和 高碳酸血症对基线血管状态和大胆反应的影响以及(2)研究表明 年轻人(20-45岁)和老年人(65-95岁)的基线血管状态和大胆反应 研究对象。 与公共卫生的相关性拟议的研究可望提供以下所需的知识 0.1赫兹频谱指数在改进功能磁共振研究解释中的应用。例如，有一次 验证了0.1赫兹频谱指数的预测能力，可以应用于研究 评估治疗精神疾病的各种药物的疗效。通过使调查人员能够评估 大胆反应中与药物相关的变化是否反映了神经活动的变化，或者主要是 作为药物对血管影响的反映，0.1赫兹的频谱指数将使研究人员能够 更有效地确定哪些药物可能具有临床价值。

Project Summary Since its introduction just over a decade ago, functional magnetic resonance imaging (fMRI) has rapidly become an indispensable tool for studies of the working human brain. The vast majority of fMRI studies utilize the blood oxygenation level dependent (BOLD) signal, which reflects the hemodynamic response to neural activity. In these studies, differences in the BOLD signal are typically interpreted as differences in neural activity. However, there is growing evidence that shifts in the baseline vascular state due to factors such as medication, age,and disease can significantly alter the amplitude and shape of the BOLD signal. These factors can increase the variability of the BOLD signal across subjects and experimental conditions and complicate the interpretation of fMRI experiments. The goal of this application is to determine whether non-invasive measures of the baseline vascular state can account for the variability in the BOLD signal that is caused by vasoactive agents and the aging process. The central hypothesis of this proposal, which is supported by strong preliminary data, is that a normalized measure of the power in low frequency components of the BOLD signal, referred to as the 0.1 Hz spectral index, can be used to probe the baseline vascular state and can account for a significant fraction of the variability in the BOLD response. The aims of this proposal are to (1) evaluate the ability of the 0.1 Hz spectral index and other measures of the baseline vascular state to account for the variability in the BOLD response caused by vasoactive agents, and (2) evaluate the ability of these measures to account for age-related variability in the BOLD response. These aims will be achieved using (1) studies that assess the impact of caffeine and hypercapnia on the baseline vascular state and the BOLD response and (2) studies that characterize the baseline vascular state and the BOLD response in young (20 to 45 years old)and old (65 to 95 years old) subjects. Relevance to Public Health The proposed studies are expected to provide the knowledge necessary for the application of the 0.1 Hz spectral index to the improved interpretation of fMRI studies. For example, once the predictive capability of the 0.1 Hz spectral index is demonstrated, it could be applied to studies evaluating the efficacy of various medications for mental illness. By enabling investigators to assess whether medication-related changes in the BOLD response reflect changes in neural activity or are primarily a reflection of the vascular effects of the medication, the 0.1 Hz spectral index would allow investigators to more effectively determine which medications are likely to be of clinical value.