Biophysical basis of functional MRI of white matter

白质功能性 MRI 的生物物理基础

• 批准号: 10333348
• 负责人: John C Gore
• 金额: $ 48.1万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10333348
• 关键词: Action Potentials; Alzheimer' s Disease; Area; Back; Biophysical Process; Biophysics; Blood; Blood Volume; Blood flow; Brain; Characteristics; Contrast Media; Coupling; Data; Degenerative Disorder; Detection; Development; Diffusion; Diffusion Magnetic Resonance Imaging; Disease; Event; Exhibits; Face; Failure; Fingers; Foundations; Functional Magnetic Resonance Imaging; Future; Gaussian model; Goals; Human; Hypercapnia; Image; Laboratories; Magnetic Resonance Imaging; Mathematics; Measurable; Measurement; Measures; Methods; Modeling; Motor; Multiple Sclerosis; Nature; Neuroglia; Noise; Oxygen; Parkinson Disease; Pathologic; Physiologic pulse; Physiological; Predisposition; Protocols documentation; Reporting; Research; Residual state; Rest; Role; Short-Term Memory; Signal Transduction; Stimulus; Stroke; Structure; Techniques; Uncertainty; Variant; Vasodilation; Visual; Work; blood oxygen level dependent; blood oxygenation level dependent response; design; detection method; detection sensitivity; fusiform face area; gray matter; hemodynamics; interest; nonhuman primate; relating to nervous system; response; success; tractography; white matter

Abstract The proposed research aims to measure blood oxygenation level dependent (BOLD) signals in white matter (WM) using functional magnetic resonance imaging (fMRI), validate their relationships to cortical neural activity, and quantify their characteristics and their underlying biophysical origins. BOLD signals have previously been robustly detected in gray matter (GM) in response to stimuli in a very large number of studies. In addition, correlations of signal fluctuations between cortical regions in a resting state have been analyzed to derive functional connectivity. However, whether such signals reliably arise in WM remains controversial, and their interpretation is unclear. We have previously shown that BOLD signals can be reliably detected in WM if appropriate detection and analysis methods are used, and that in a resting state they exhibit anisotropic temporal correlations that largely align with WM tracts. Multiple such lines of evidence converge to suggest that WM BOLD signals are related to intrinsic, function-dependent neural activity and are apparent only in tracts engaged in specific functions. However, the precise relationships between WM and corresponding GM signals have not been established, and neither the characteristics nor origins of the hemodynamic response function (HRF) of WM have been elucidated. We hypothesize that BOLD signal variations in WM tracts are directly related to corresponding variations in neural activity in GM volumes to which they connect and/or which share specific functional roles, and that further studies will provide a new basis for more fully integrating structural and functional aspects of neural organization. In the proposed research we will [1] demonstrate and measure the relationships between BOLD signals in WM tracts (identified using diffusion imaging) and GM volumes in response to parametric stimuli whose variations modulate the degree of neural activity in specific cortical areas; [2] measure and characterize the HRF in specific WM tracts using event-related fMRI, and modify conventional models of BOLD responses to explain and fit those data; [3] establish the biophysical basis of stimulus-evoked BOLD activations in white matter by comparing data from different imaging sequences and field strengths, and by measuring BOLD signals in the brains of non-human primates with and without an intravascular susceptibility contrast agent to separate contributions from changes in blood volume vs blood oxygenation. Overall, these studies will validate the nature of WM BOLD effects, demonstrate their relevance in neural processing, and provide a basis for future studies of functional changes in a broad range of WM- associated disorders as well as development and degeneration.

抽象的 拟议的研究旨在测量白质中的血液氧合水平（BOLD）信号 （WM）使用功能磁共振成像（fMRI），验证其与皮质神经活动的关系， 并量化其特征及其潜在的生物物理起源。大胆的信号以前是 在大量研究中，在灰质（GM）中对刺激的响应进行了稳健检测。此外， 已经分析了静止状态的皮质区域之间信号波动的相关性，以得出 功能连接。但是，此类信号是否可靠地出现在WM中仍然存在争议，它们的 解释尚不清楚。我们以前已经表明，如果在WM中可以可靠地检测到BOLD信号 使用了适当的检测和分析方法，并且在静止状态下它们表现出各向异性 时间相关性在很大程度上与WM段对齐。多种这样的证据汇合，表明 WM BOLD信号与固有的，功能依赖性的神经活动有关，仅在区域中明显 从事特定功能。但是，WM与相应的GM信号之间的精确关系 尚未建立，并且既不是血液动力学响应函数的特征和起源 WM的（HRF）已阐明。我们假设WM道中的粗体信号变化直接 与它们连接和/或共享的GM卷中神经活动的相应变化有关 特定的功能角色，进一步的研究将为更充分整合结构提供新的基础 和神经组织的功能方面。在拟议的研究中，我们将[1]证明和衡量 WM道中的粗体信号（使用扩散成像鉴定）与GM体积之间的关系 对参数刺激的反应，其变化调节特定皮质的神经活动程度 区域； [2]使用与事件相关的fMRI测量并表征特定WM中的HRF，然后修改 传统的大胆响应模型来解释和拟合这些数据； [3]建立生物物理基础 通过比较来自不同成像序列的数据和 野外强度，并通过测量有或没有的非人类灵长类动物的大脑中的大胆信号 血管内敏感性对比剂，与血液体积变化与血液的变化分开贡献 氧合。总体而言，这些研究将验证WM Bold效果的性质，证明了它们的相关性 在神经加工中，为将来的研究提供了广泛的WM-功能变化的基础 相关疾病以及发展和变性。