Sources and implications of whole-brain fMRI signals in humans.
Sources and implications of whole-brain fMRI signals in humans.
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DOI：
10.1016/j.neuroimage.2016.09.038
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发表时间：
2017-02-01
期刊：
影响因子：
5.7
通讯作者：
Martin A
中科院分区：
文献类型：
--
作者：
Power JD;Plitt M;Laumann TO;Martin A
全脑功能磁共振成像信号是一个非常感兴趣的课题：整体功能磁共振成像信号（大脑中所有信号的空间平均值）的变化指示受试者的觉醒，精神分裂症和自闭症等精神疾病的特征是整体功能磁共振成像信号的差异。此外，关于是否应该从fMRI数据中删除全局信号存在激烈的争论。然而，令人惊讶的是，很少有研究集中在全脑功能磁共振成像信号的经验性质。在这里，我们映射的空间和时间属性的全球信号，分别在1000+ fMRI扫描。全局fMRI信号的变化与头部运动、硬件伪影、呼吸模式及其伴随的生理变化密切相关。许多用于准备功能性磁共振成像数据进行分析的技术都无法消除这些令人不感兴趣的全局信号波动。因此，许多研究在分析时包括哈欠、呼吸变化和头部运动等信号的显著全局效应。这样的伪像将模仿动态神经活动，并将虚假地改变整个大脑的信号协方差。需要能够隔离和去除全局人为方差的方法，同时保留假定的“神经”方差;本文对全局信号回归的主题不采取任何立场。
Whole-brain fMRI signals are a subject of intense interest: variance in the global fMRI signal (the spatial mean of all signals in the brain) indexes subject arousal, and psychiatric conditions such as schizophrenia and autism have been characterized by differences in the global fMRI signal. Further, vigorous debates exist on whether global signals ought to be removed from fMRI data. However, surprisingly little research has focused on the empirical properties of whole-brain fMRI signals. Here we map the spatial and temporal properties of the global signal, individually, in 1000+ fMRI scans. Variance in the global fMRI signal is strongly linked to head motion, to hardware artifacts, and to respiratory patterns and their attendant physiologic changes. Many techniques used to prepare fMRI data for analysis fail to remove these uninteresting kinds of global signal fluctuations. Thus, many studies include, at the time of analysis, prominent global effects of yawns, breathing changes, and head motion, among other signals. Such artifacts will mimic dynamic neural activity and will spuriously alter signal covariance throughout the brain. Methods capable of isolating and removing global artifactual variance while preserving putative “neural” variance are needed; this paper adopts no position on the topic of global signal regression.