Farrand Jesse, Tang Julia, O'Keeffe Johnny
Annu Int Conf IEEE Eng Med Biol Soc. 2017 Jul;2017:537-540. doi: 10.1109/EMBC.2017.8036880.
Most of the prior studies of functional connectivity in both healthy and diseased brain utilized resting-state functional magnetic resonance imaging (fMRI) as a measure to represent the temporal synchrony in blood oxygenation level dependent (BOLD) signals across brain regions. To eliminate the impact of widely distributed global signal component across the brain, many studies have adopted global signal regression (GSR) as a pre-processing approach to regress the global signal component out of BOLD signals followed by computing hemodynamic connectivity. However, the procedure of global signal regression has been debated as physiologically relevant component may be present in global signal. In this study, we aimed to address the controversy of global signal using functional non-invasive neuroimaging technology, i.e. functional near-infrared spectroscopy (fNIRS), which measures hemodynamic signals by probing local changes in oxygen consumption, a common imaging contrast measured by BOLD fMRI. In the current study, we acquired simultaneous EEG and fNIRS signals, both in high-density configuration and whole-brain coverage, in healthy individuals at eyes-open and eyes-closed resting state and at three different body positions. We explored the underlying relationship between fNIRS global signal and EEG vigilance, and have identified negative correlation between fNIRS global signal and EEG vigilance across the physiological variations of measurements.
先前大多数关于健康和患病大脑功能连接性的研究都利用静息态功能磁共振成像（fMRI）作为一种测量方法，来表示大脑区域间血氧水平依赖（BOLD）信号的时间同步性。为了消除大脑中广泛分布的全局信号成分的影响，许多研究采用全局信号回归（GSR）作为一种预处理方法，从BOLD信号中回归出全局信号成分，然后计算血流动力学连接性。然而，全局信号回归的过程一直存在争议，因为全局信号中可能存在生理相关成分。在本研究中，我们旨在利用功能性非侵入性神经成像技术，即功能性近红外光谱（fNIRS）来解决全局信号的争议，fNIRS通过探测氧消耗的局部变化来测量血流动力学信号，这是一种通过BOLD fMRI测量的常见成像对比。在当前研究中，我们在健康个体睁眼、闭眼静息状态以及三种不同身体姿势下，同时采集了高密度配置和全脑覆盖的脑电图（EEG）和fNIRS信号。我们探索了fNIRS全局信号与EEG警觉性之间的潜在关系，并在测量的生理变化中确定了fNIRS全局信号与EEG警觉性之间的负相关。
