Removal of confounding effects of global signal in functional MRI analyses
Removal of confounding effects of global signal in functional MRI analyses
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DOI：
10.1006/nimg.2000.0719
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发表时间：
2001-04-01
期刊：
影响因子：
5.7
通讯作者：
Liddle, PF
中科院分区：
文献类型：
--
作者：
Desjardins, AE;Kiehl, KA;Liddle, PF
从BOLD fMRI获得的局部信号通常被全局效应混淆。在本文中，我们做了一个本质上的区别之间的整体效应和整体信号。全局效应对来自大比例脑体素的局部信号具有类似的影响。它们可能反映了弥漫性的生理过程或扫描仪灵敏度的变化，并且难以直接测量。通常从全局信号估计全局效应，全局信号是来自所有大脑体素的局部信号的空间平均值。如果全局信号与实验操作密切相关，则无论是否对全局效应进行建模，都可能获得有意义的不同结果（G。K. Aguirre等，1998，NeuroImage，8，302-306）。特别是，如果局部BOLD信号对全局信号有显著贡献，则使用ANCOVA或比例缩放模型的分析可能会产生人为失活。在本文中，我们提出了一个修改的比例密封模型，占本地BOLD信号的全球信号的贡献。一个事件相关的oddball刺激范式和一个块设计的工作记忆任务被用来说明我们的模型的有效性。(C)北京：科学出版社.
Local signals obtained from BOLD fMRI are generally confounded by global effects. In this paper, we make an essential distinction between global effects and the global signal. Global effects have a similar influence on local signals from a large proportion of cerebral voxels. They may reflect diffuse physiological processes or variations in scanner sensitivity and are difficult to measure directly. Global effects are often estimated from the global signal, which is the spatial average of local signals from all cerebral voxels. If the global signal is strongly correlated with experimental manipulations, meaningfully different results may be obtained whether or not global effects are modeled (G. K. Aguirre ct al, 1998, NeuroImage, 8, 302-306). In particular, if local BOLD signals make a significant contribution to the global signal, analyses using ANCOVA or proportional scaling models may yield artifactual deactivations. In this paper, we present a modification to the proportional sealing model that accounts for the contribution of local BOLD signals to the global signal. An event-related oddball stimulus paradigm and a block design working memory task were used to illustrate the efficacy of our model. (C) 2001 Academic Press.