Functional MRI at Columnar Resolution

柱状分辨率的功能 MRI

• 批准号: 8814220
• 负责人: MITSUHIRO FUKUDA
• 金额: $ 30.46万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-12-01 至 2016-09-07
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8814220
• 关键词: Animals; Blood; Blood Volume; Blood capillaries; Brain; Cerebrovascular Circulation; Cerebrum; Communities; Contrast Media; Cortical Column; Data; Development; Felis catus; Functional Magnetic Resonance Imaging; Funding; Goals; Grant; Human; Imaging Techniques; Injection of therapeutic agent; Investigation; Longitudinal Studies; Maps; Measurement; Measures; Medical; Methods; Modeling; Oxygen measurement, partial pressure, arterial; Patients; Physiological; Recovery; Research; Resolution; Role; Sensitivity and Specificity; Signal Transduction; Slice; Source; Specificity; Stimulus; Structure; Techniques; Time; Tissues; Veins; Visual Cortex; Weight; arteriole; base; blood oxygen level dependent; capillary; deoxyhemoglobin; design; hemodynamics; improved; magnetic field; millimeter; novel; optical imaging; orientation columns; relating to nervous system; response; tool

DESCRIPTION (provided by applicant): Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is an essential tool for mapping human brain activity in the medical and scientific communities. Despite its indispensable role, BOLD fMRI has not been routinely used to map sub-millimeter functional structures due to draining vein contributions, a relatively broad point spread function, and low neural activity-specific signal sensitivity. Multipe approaches to overcome these problems have included the use of ultrahigh magnetic fields, improved imaging techniques, and continuous cyclic stimulation paradigm (vs. block design). During the last grant period, optical imaging of intrinsic signals (OIS) confirmed that with these improvements, high BOLD fMRI responses co- localize with active orientation columns, thus demonstrating that functional columns can be mapped with hemodynamic-based fMRI. However, even with these approaches, the physiological source of columnar- resolution BOLD fMRI signals is unclear and there is relatively poor signal contrast between active and inactive columns. High-specificity fMRI techniques must be further explored and optimized before they can be more widely applied to the study of basic mechanisms with relevance to human brain. In this competitive renewal application investigating a well-established orientation column model of the cat visual cortex at 9.4 Tesla, we aim to systematically determine the physiological source of columnar-resolution BOLD fMRI signals, and investigate whether these signals can be enhanced non-invasively. Specific Aim #1 is to determine the physiological source of columnar-resolution BOLD fMRI signals. There is an apparent discrepancy between BOLD and OIS results for neuronally-active vs. neighboring inactive columns; BOLD results suggest highest hyper-oxygenation in active columns, while OIS studies suggest highest hyper-oxygenation in inactive columns. To determine the physiological sources of columnar-resolution BOLD fMRI signals, BOLD fMRI, tissue oxygen tension, multi-unit activity, and OIS will be measured whether highest hyper-oxygenation occurs during stimulation at preferred or at non-preferred orientations. We hypothesize that change in the blood oxygenation levels are not the dominant contribution to column-specific BOLD fMRI responses. Specific Aim #2 is to enhance sub-millimeter column-specific fMRI signals by non-invasive methods. BOLD fMRI has relatively poor sub-millimeter column-specific signal, thus its sensitivity may be enhanced with cerebral blood flow (CBF)-weighted fMRI and cerebral blood volume (CBV)-weighted fMRI. Thus, we propose to compare non-invasive, sub-millimeter column-specific responses for multiple techniques including BOLD fMRI, arterial CBV-enhanced fMRI with magnetization transfer effect, and CBF-enhanced fMRI. We hypothesize that non- invasive arterial CBV-weighted and CBF-weighted fMRI techniques will show enhanced fMRI responses from sub-millimeter functional structures. The long-term goal of these investigations is to improve the capability of mapping responses from fine functional structures in both animals and humans non-invasively.

描述（由申请人提供）：血液氧合水平依赖性（BOLD）功能磁共振成像（fMRI）是绘制医学和科学群落中人脑活动的重要工具。尽管它具有必不可少的作用，但由于排干静脉的贡献，相对较宽的点扩散功能和低神经活动特异性信号敏感性，因此尚未常规地使用BOLD FMRI来绘制亚毫米毫米功能结构。克服这些问题的多种方法包括使用超高磁场，改进的成像技术和连续的循环刺激范式（相对于块设计）。在最后一个赠款期间，内在信号（OIS）的光学成像证实，通过这些改进，高BOLD FMRI响应与主动取向柱共同定位，因此证明功能柱可以与基于血液动力学的FMRI映射。但是，即使采用了这些方法，柱状分辨率BOLD FMRI信号的生理来源尚不清楚，并且有效柱和非活动柱之间的信号对比相对较差。必须对高特异性fMRI技术进行进一步探索和优化，然后才能更广泛地将其应用于与人脑相关的基本机制的研究。在此竞争性更新应用程序中，调查了9.4 Tesla Cat Visual Cortex的良好方向柱模型，我们旨在系统地确定柱状分辨率BOLD FMRI信号的生理来源，并研究这些信号是否可以非侵入性地增强。特定目的＃1是确定柱状分辨率BOLD FMRI信号的生理来源。对于神经活性与邻近不活动柱的粗体和OIS结果之间存在明显的差异。大胆的结果表明在活性柱中最高的高充氧，而OIS研究表明在不活动柱中最高的高充氧。为了确定柱状分辨率BOLD FMRI信号的生理来源，BOLD FMRI，组织氧张力，多单位活性和OI，是否在首选或非偏爱方向上的刺激期间发生最高的高氧。我们假设血液氧合水平的变化不是对特定柱特异性BOLD FMRI反应的主要贡献。特定的目的＃2是通过非侵入性方法增强亚毫米柱特异性fMRI信号。 BOLD FMRI具有相对较差的亚毫米柱特异性信号，因此，通过大脑血流（CBF）加权fMRI和脑血体积（CBV）加权fMRI可以增强其敏感性。因此，我们建议对多种技术进行非侵入性，亚毫米柱特异性响应，包括大胆的fMRI，动脉CBV增强fMRI具有磁化转移效果和CBF增强fMRI。我们假设非侵入性动脉CBV加权和CBF加权FMRI技术将显示出亚毫米功能结构的FMRI响应增强。这些研究的长期目标是提高动物和人类中精细功能结构的映射反应的能力。