FUNDAMENTALS OF FUNCTIONAL MAGNETIC RESONANCE IMAGING

该项目的长期目标是对人类功能磁共振成像(FMRI)中任务诱发对比的基本生物物理和生理机制有一个基本的了解。这一认识将有助于改进功能磁共振成像技术，促进对脑血流动力学局部控制的认识，并为功能磁共振成像技术在神经科学领域的应用奠定基础。4篇论文、2篇博士论文和101篇摘要描述了在前一资助时期实现这一目标的进展情况。本项目的假设是，动态血氧水平依赖(BOLD)功能磁共振成像对比度是随时间和空间变化的血管和代谢成分的复杂积分，并且如果有足够的先验信息，对BOLD信号的特定方面的测量可以提供关于任务激活引起的生理事件的唯一信息。这一假说在四个特定目标下得到验证，每个目标都涉及在人类和大鼠胡须桶皮质中进行的平行研究，该模型是在前一个资助期开发的功能磁共振模型：(1)确定血管结构对功能磁共振信号的影响；(2)将功能磁共振信号的空间范围与神经元激活相关联；(3)更好地描述功能磁共振时间模式；以及(4)更深入地研究潜在的生理波动。这项研究将基于最近的几项突破，包括：(1)通过使用部分k空间梯度回波平面成像极大地提高了fMRI的空间分辨率；(2)使用嵌入式对比度来精确比较任务激活响应与两个独立变量；(3)增强了对fMRI数据集潜在生理波动的理解；以及(4)使用局部梯度Coli技术改进了3T扫描仪，以获得最先进的灵敏度和稳定性。新的具体目标的议定书沿袭了前一个供资期间的工作，但在取得实质性进展的基础上增加了具体和详细的内容。功能磁共振成像是朝着了解大脑功能的目标迈出的真正重要的一步，对人类健康具有巨大的潜在影响。它必须有坚实的基础，以严谨的生物物理和生理学研究为基础。

The broad long-term objective of this Project is to obtain a fundamental understanding of the basic biophysical and physiological mechanisms of task induced contrasts in human functional magnetic resonance imaging (fMRI). This understanding can be expected to lead to improved fMRI technology, to contribute to knowledge about local control of cerebral hemodynamics, and to provide a basis for the application of fMRI to the field of neuroscience. Progress towards this objective in the previous funding period is described in 4 papers, 2 PhD dissertations, and 101 abstracts. The hypothesis of this Project is that dynamic blood oxygen level-dependent (BOLD) fMRI contrast is a complex integral of vascular and metabolic component that vary over time and space, and that with sufficient a complex integral of vascular and metabolic components that vary over time and space, and that with sufficient a priori information, measurement of particular aspects of the BOLD signal can provide unique information about the physiological events resulting from task activation. This hypothesis is tested in four specific aims, each of which involves parallel studies in humans and in the rat whisker-barrel cortex, an fMRI model that was developed in the previous funding period: (1) to determine the effects of vascular architecture on the fMRI signal; (2) to correlate the spatial extent of the fMRI signal with neuronal activation; (3) to better characterize fMRI temporal patterns; and (4) to pursue in greater depth the study of underlying physiological fluctuations. The research will be based on several recent breakthroughs including: (1) greatly enhanced fMRI spatial resolution through the use of partial k- space gradient-recalled echo-planar imaging; (2) use of embedded contrast for precise comparison of task-activation response to two independent variables; (3) enhanced understanding of underlying physiological fluctuations in fMRI data sets; and (4) refinements of the 3 T scanner for state-of-the-art sensitivity and stability using local gradient coli technology. The protocols of the new specific aims follow from the work of the previous funding period, but at increased specificity and detail based on the substantial progress that was made. Functional MRI is a truly significant advance towards the goal of understanding brain function, with enormous potential impact on human health. It is essential that it have a firm foundation that is based on rigorous biophysical and physiological studies.