Global Signal Correction in Resting State fMRI

描述(申请人提供)：静息状态功能连接磁共振成像(FcMRI)最近成为非侵入性表征人脑功能连接的领先方法。在fcMRI研究中，衡量两个大脑区域之间连通性的标准指标是它们各自的静息状态功能磁共振(FMRI)时间序列之间的时间相关性。对于相关性的计算，许多研究使用称为全局信号回归(GSR)的预处理步骤，在该步骤中，从所有体素时间过程中减去全局平均信号。虽然GSR可以极大地提高功能连通性地图的一致性和可靠性，但它的使用存在争议，因为它也可能引入虚假的负相关性。目前，关于如何更好地处理全球信号混淆问题还没有明确的共识，许多fcMRI研究仍在继续使用GSR，而其他研究则由于对GSR的担忧而采用了替代方法。这种共识的缺乏使得比较fcMRI研究变得困难，因为不同的方法可能产生显著不同的连通性测量。该项目的目标是更好地了解全球信号，并利用这一知识开发全球信号校正的新方法。这项研究的目的是(1)开发和评估一种新的全局信号校正方法，以及(2)确定全局信号变化是否反映了潜在神经电相干性的变化。

DESCRIPTION (provided by applicant): Resting-state functional connectivity magnetic resonance imaging (fcMRI) has recently emerged as a leading method for non-invasively characterizing the functional connections of the human brain. In fcMRI studies, a standard measure of connectivity between two brain regions is the temporal correlation between their respective resting-state functional MRI (fMRI) time series. For the computation of correlations, many studies use a pre-processing step known as global signal regression (GSR), in which a global mean signal is subtracted from all voxel time courses. While GSR can greatly improve the consistency and reliability of functional connectivity maps, its use is controversial because it may also introduce spurious negative correlations. Currently, there is not a clear consensus regarding how to best handle global signal confounds, with many fcMRI studies still continuing to use GSR, while others have adopted alternate methods due to concerns about GSR. This lack of agreement makes it difficult to compare fcMRI studies, as differing approaches can yield significantly different connectivity measures. The goals of this project are to develop a better understanding of the global signal and to use that knowledge to develop new methods for global signal correction. The aims of the study are to (1) Develop and evaluate a new approach for global signal correction and (2) Determine whether global signal variations reflect changes in underlying neuroelectric coherence.