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氧水平依赖性（BOLD）信号 (WM) 使用功能磁共振成像 (fMRI)，验证它们与皮质神经活动的关系， 并量化它们的特征及其潜在的生物物理起源。 BOLD 信号之前已 在大量研究中，在灰质（GM）中对刺激的反应中被可靠地检测到。此外， 分析静息状态下皮质区域之间信号波动的相关性，得出 功能连接。然而，此类信号在 WM 中是否可靠地出现仍存在争议，而且它们的 解释不清楚。我们之前已经证明，如果 使用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 时间相关性很大程度上与 WM 区域一致。多个此类证据汇聚在一起表明 WM BOLD 信号与内在的、功能依赖性的神经活动相关，并且仅在束中明显 从事特定职能。然而，WM 和相应 GM 信号之间的精确关系 尚未建立，血流动力学反应函数的特征和起源都没有建立 (HRF) WM 已被阐明。我们假设 WM 束中的 BOLD 信号变化直接与 与它们连接和/或共享的 GM 体积中神经活动的相应变化有关 特定的功能作用，进一步的研究将为更充分地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]展示和测量 WM 束中的 BOLD 信号（使用扩散成像识别）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 地区； [2] 使用事件相关的 fMRI 测量和表征特定 WM 束中的 HRF，并修改 用于解释和拟合这些数据的 BOLD 响应的传统模型； [3]建立生物物理学基础 通过比较不同成像序列的数据和刺激诱发的白质 BOLD 激活 场强，并通过测量有或没有磁场的非人类灵长类动物大脑中的 BOLD 信号 血管内磁敏感造影剂可区分血容量与血液变化的贡献 氧合。总体而言，这些研究将验证 WM BOLD 效应的本质，证明其相关性 神经处理，并为未来研究广泛的 WM-功能变化提供基础 相关疾病以及发育和退化。