FUNDAMENTALS OF FUNCTIONAL MAGNETIC RESONANCE IMAGING

该项目的广泛的长期目标是获得对人类功能磁共振成像（fMRI）中任务诱导对比度的基本生物物理和生理机制的基本理解。这一认识将有助于改进功能磁共振成像技术，有助于了解脑血流动力学的局部控制，并为功能磁共振成像在神经科学领域的应用提供基础。在前一个资助期内，在4篇论文，2篇博士论文和101篇摘要中描述了这一目标的进展。本项目的假设是，动态血氧水平依赖（BOLD）fMRI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，并且具有随时间和空间变化的血管和代谢成分的足够复杂积分，并且具有足够的先验信息，BOLD信号的特定方面的测量可以提供关于由任务激活引起的生理事件的唯一信息。这一假设在四个特定的目标中进行了测试，每个目标都涉及对人类和大鼠须桶皮层的平行研究，这是一个在前一个资助期开发的fMRI模型：（1）确定血管结构对fMRI信号的影响;（2）将fMRI信号的空间范围与神经元激活相关联;（3）更好地表征fMRI时间模式;（4）确定血管结构对fMRI信号的影响。（4）更深入地研究潜在的生理波动。该研究将基于最近的几项突破，包括：（1）通过使用部分k空间梯度回忆回波平面成像大大提高了fMRI的空间分辨率;（2）使用嵌入对比度精确比较任务激活对两个自变量的反应;（3）增强对fMRI数据集中潜在生理波动的理解;和（4）使用局部梯度大肠杆菌技术改进3 T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用了上一个供资期的工作，但在取得实质性进展的基础上更加具体和详细。功能性磁共振成像是理解大脑功能的一个真正重要的进步，对人类健康具有巨大的潜在影响。它必须有一个坚实的基础，以严格的生物物理和生理研究为基础。

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.