Relating functional MRI to neuronal activity: accounting for effects of microarchitecture

将功能 MRI 与神经元活动联系起来：解释微结构的影响

• 批准号: 10677777
• 负责人: Anna I Blazejewska
• 金额: $ 24.9万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10677777
• 关键词: Accounting; Address; Affect; Anatomy; Animals; Area; Atlases; Award; BRAIN initiative; Back; Blood; Blood Vessels; Blood flow; Brain; Brain region; Cell Nucleus; Cerebral cortex; Cerebrum; Characteristics; Consultations; Contrast Media; Data; Data Analyses; Experimental Designs; Face; Feedback; Functional Imaging; Functional Magnetic Resonance Imaging; General Hospitals; Goals; Heme; Histologic; Histology; Human; Image; Imaging Techniques; Individual; Investigation; Iron; Knowledge; Magnetic Resonance Imaging; Maps; Masks; Massachusetts; Measurement; Measures; Mentors; Methodology; Methods; Microanatomy; Modeling; Myelin; Neocortex; Neurons; Neurosciences; Output; Pathway interactions; Phase; Physics; Property; Research; Research Personnel; Resolution; Role; Signal Transduction; Source; Specificity; Specimen; Stains; Stimulus; Structure; System; Techniques; Technology; Testing; Tissue Model; Tissues; Training; Variant; Visual Cortex; area striata; biomedical imaging; brain circuitry; career; cerebral blood volume; collaborative environment; computer science; density; experience; experimental study; extrastriate visual cortex; histological specimens; human data; imaging facilities; in vivo; in vivo imaging; indexing; luminance; medical schools; millimeter; monocular; neural; neuronal circuitry; novel; programs; regional difference; response; skills

The central goal of the BRAIN Initiative is to understand the structure and function of human brain circuits. Functional magnetic resonance imaging (fMRI) has great potential to achieve this goal, however fMRI is fundamentally an indirect measure of neuronal activity—it assesses brain function through the measurement of changes in blood flow and oxygenation driven by local neuronal activity, and is also influenced by regional differences in tissue anatomy including vascular density. The cerebral cortex consists of layers that are well- known to serve as inputs or outputs for the connections across brain regions, and so localizing fMRI signals to individual layers will be key to deciphering brain circuitry in humans. However, the cortical microanatomy varies dramatically across layers, introducing biases that have been demonstrated to confound our ability to detect and localize activity within layers with fMRI, and therefore to hinder the interpretation and use of laminar fMRI. Our aim is to characterize and remove these fMRI signal biases due to local differences in microanatomy, in order to address this fundamental limitation of fMRI and to more accurately relate fMRI to neuronal activity. We will achieve this goal by combining histology of human brain specimens with advanced ex vivo and in vivo imaging to develop a framework for enhancing fMRI neuronal specificity—through deriving a mapping between tissue microarchitecture and quantitative MRI, and then correcting fMRI signal bias related to tissue microstructure. The candidate is trained in physics and computer science; has experience in high-resolution structural MRI and in correlating in vivo and ex vivo MRI with histology; and seeks training in experimental neuroscience in order to become an independent researcher in this field. During the mentored phase, she will develop a model of intracortical microstructure using ex vivo data from regions of visual cortex. She will measure vascular density in vivo to map out this additional source of fMRI signal bias, then develop a model to derive predictions of cortical microstructure and fMRI responses in vivo, and validate it through an fMRI experiment using a wide range of acquisition parameters. To achieve these goals, the candidate—with guidance from the experienced mentors, the pioneers of laminar microanatomy and fMRI—will extend her knowledge, gain new skills in advanced ultra- high-field fMRI acquisition and data analysis. Building on this, in the independent phase she will apply the model to laminar fMRI experiments designed to validate the bias correction. This project will prepare the candidate for her long-term career goal of establishing a research program applying non-invasive functional imaging techniques, with aid of quantitative tissue property analyses, to study the circuitry of the human brain. The mentored phase will be carried out at the Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, a highly collaborative environment with state-of-the-art imaging facilities and world-class experts available for mentoring/consultation. The K99 award will facilitate the required training and research components of this project to aid the candidate in becoming an independent researcher.

大脑倡议的中心目标是了解人类大脑回路的结构和功能。功能磁共振成像(FMRI)具有实现这一目标的巨大潜力，然而fMRI基本上是对神经元活动的间接测量-它通过测量局部神经元活动驱动的血流量和氧合的变化来评估大脑功能，并且还受到包括血管密度在内的组织解剖的区域差异的影响。众所周知，大脑皮层由几个层组成，这些层是跨大脑区域连接的输入或输出，因此将fMRI信号定位到各个层将是破译人类大脑电路的关键。然而，皮质显微解剖在各层之间差异很大，引入的偏差已被证明混淆了我们使用fMRI检测和定位层内活动的能力，因此阻碍了对层流fMRI的解释和使用。我们的目标是表征和消除由于显微解剖学上的局部差异而导致的这些fMRI信号偏差，以解决fMRI的这一根本限制，并更准确地将fMRI与神经元活动联系起来。我们将通过将人脑标本的组织学与先进的体外和体内成像相结合来开发一个增强fMRI神经元特异性的框架-通过推导组织微结构和定量MRI之间的映射，然后校正与组织微结构相关的fMRI信号偏差，来实现这一目标。应聘者受过物理和计算机科学方面的培训；在高分辨率结构核磁共振以及体内和体外核磁共振与组织学的关联方面有经验；并寻求实验神经科学方面的培训，以便成为该领域的独立研究人员。在指导阶段，她将使用来自视觉皮质区域的体外数据开发皮质内微结构模型。她将测量体内的血管密度，以绘制出这一额外的fMRI信号偏差来源，然后开发一个模型，以推导出体内皮质微结构和fMRI反应的预测，并使用广泛的采集参数通过fMRI实验进行验证。为了实现这些目标，候选人将在经验丰富的导师、椎板显微解剖学和功能磁共振成像的先驱的指导下，扩展她的知识，获得先进的超高场功能磁共振成像采集和数据分析方面的新技能。在此基础上，在独立阶段，她将把该模型应用于层流fMRI实验，旨在验证偏差校正。这个项目将为候选人的长期职业目标做好准备，她的目标是建立一个研究项目，应用非侵入性功能成像技术，借助定量组织特性分析，研究人脑的回路。指导阶段将在马萨诸塞州总医院、哈佛医学院的阿蒂努拉·A·马蒂诺斯生物医学成像中心进行，这是一个高度协作的环境，拥有最先进的成像设备和可供指导/咨询的世界级专家。K99奖将促进该项目所需的培训和研究部分，以帮助候选人成为一名独立研究人员。