期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：39
页码：19243-19244
DOI：10.1073/pnas.1909852116
出版社：The National Academy of Sciences of the United States of America
摘要：In 2 human functional magnetic resonance imaging (fMRI) datasets (89 “ME” subjects; 12 “NA” subjects), we used signal decay properties to separate 2 kinds of signals: S0 artifacts, which were spatially specific, and T2* modulations, which occurred over the whole brain (1). We established that whole-brain (global) fMRI signals were nearly unchanged before and after removal of S0 signals. Hence, most global signals are T2* signals, compatible with neural activity or with respiratory-related pCO2 changes. In a dataset with paired respiratory records (NA data), we illustrated that changes in respiratory traces were temporally accompanied by prominent global signal modulations, an association visible in “gray plots” of single scans (2). Across scans, variance in global signals correlated with variance in respiratory measures. Spreng et al. (3) critique our paper, stating that “there is no definitive evidence . . . that respiration effects . . . even substantively contribute . . . to residual global signal [following removal of S0 .
