Abstract
Global signal fluctuations are a dominant source of variance in spontaneous BOLD activity. These brain-wide signals co-occur with respiratory and other physiological changes. An often-overlooked possibility is that these physiological associations with global BOLD fluctuations are components of a unified physiological process. Here we combine analysis of multi-modal physiological recordings with simultaneous EEG-fMRI data to demonstrate that global BOLD fluctuations are embedded in a physiological network spanning neural, cardiovascular, pulmonary, exocrine (sweat glands) and smooth muscle (pupil dilator) systems. We further show that these co-fluctuations can be initiated by voluntary changes in respiratory rate and depth. We propose that respiratory variability and its concomitant physiological dynamics are essential explanatory ingredients in the origin of global BOLD fluctuations.
Competing Interest Statement
The authors have declared no competing interest.
