Take a deep breath: Multiecho fMRI denoising effectively removes head motion artifacts, obviating the need for global signal regression

Abstract

Power et al. (1) provide convincing evidence that multiecho independent components analysis (ME-ICA) effectively differentiates blood oxygen level-dependent (BOLD) from non-BOLD, or artifactual, signals in functional MRI (fMRI) data. Critically, ME-ICA removes spurious, distance-dependent effects caused by head motion in resting-state functional connectivity (RSFC) analyses, which have confounded many group studies. However, the authors also argue that ME-ICA unmasks persistent BOLD-related global signal correlates, attributed to “motion-associated” effects of respiration, and conclude that removal of this global signal by some means is necessary. Among other approaches, they recommend implementing global signal regression (GSR) following ME-ICA. To the contrary, we argue that there is no definitive evidence to date that respiration … [↵][1]1To whom correspondence may be addressed. Email: nathan.spreng{at}gmail.com or stevensd{at}yorku.ca. [1]: #xref-corresp-1-1