Shedding Near-Infrared Light on Brain Networks
Shedding Near-Infrared Light on Brain Networks
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发表时间：
2013
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通讯作者：
A. Medvedev
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作者：
A. Medvedev
近红外光谱技术是一种新型的、有前途的脑成像技术，在研究和临床实践中具有成本效益和无创性。利用近红外光主要被组织血红蛋白吸收的事实，可以测量由组织散射和反射的光的强度（例如，脑），以跟踪皮质层内血红蛋白浓度的局部变化（近红外光谱，NIRS）。此外，利用多个源-检测器对，可以对血红蛋白的氧合（HbO）和脱氧形式两者执行激活图的空间重建（在这种情况下，使用术语“漫射光学断层扫描”）。从概念上讲，NIRS检测血液动力学调制作为神经元活动的间接测量，类似于血氧水平依赖（BOLD）功能磁共振成像（fMRI）信号。尽管NIRS的空间分辨率低于fMRI（约1cm），但NIRS提供了具有优异的时间分辨率的成像方法（如在诸如EEG和MEG的电生理方法中发现的高达几ms）。此外，其低成本、便携性和易用性使其理想地适用于那些不容易接受fMRI和正电子发射断层扫描（PET）的金标准成像技术的受试者和患者群体。现代NIRS仪器提供高密度多通道记录，允许更大的头部覆盖范围，不仅可以测量大脑激活，还可以测量大脑区域之间的动态相互作用。这些相互作用可以通过从多个大脑区域同时记录的光学信号的时间相关性来评估，因此可以导出类似于通过fMRI BOLD信号测量的功能连接的基于NIR的“功能连接”[1]。
Near-infrared spectroscopy is a novel and promising technology for cost effective and noninvasive brain imaging in research and clinical practice. Utilizing the fact that near-infrared light is mostly absorbed by tissue hemoglobin, one can measure the intensity of light scattered and reflected by tissue (e.g., brain) to track local changes in hemoglobin concentrations within cortical layers (near-infrared spectroscopy, NIRS). Moreover, with multiple source-detector pairs, one can perform spatial reconstruction of an activation map for both oxygenated (HbO) and de-oxygenated forms of hemoglobin (in this case, the term ‘Diffuse Optical Tomography’ is used). Conceptually, NIRS detects hemodynamic modulations as an indirect measure of neuronal activity similar to the blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal. Although spatial resolution of NIRS is lower than that of fMRI (about 1 cm), NIRS provides an imaging method with excellent temporal resolution (up to a few ms as found in electrophysiological methods such as EEG and MEG). Moreover, its low cost, portability and the ease of use make it ideally suitable for those subject and patient populations which are not easily amenable to the gold-standard imaging techniques of fMRI and positron emission tomography (PET). The modern NIRS instruments provide high density multi-channel recordings which allow for larger coverage of the head and it becomes possible to measure not only brain activation but also dynamic interactions between the brain areas. Those interactions can be assessed through temporal correlations of optical signals simultaneously recorded from multiple brain regions and thus a NIRS-based ‘functional connectivity’ similar to the functional connectivity measured by the fMRI BOLD signal [1] can be derived.