[Article] Autonomic physiological coupling of the global fMRI signal

Summary: This study characterizes a widespread pattern of co-fluctuations between global fMRI brain signals and sympathetic-mediated physiological fluctuations in humans. This pattern of cofluctuations is replicated across multiple independent datasets of multimodal fMRI, EEG, and peripheral physiology recordings. It is widespread across the body and entire nervous system, involving the brain, heart, lungs, exocrine and smooth muscle systems. It is also linked to changes in arousal state induced via deep breathing and intermittent sensory stimulation, as well as spontaneous fluctuations in arousal observed during sleep. Here, they show that the spatial structure of global fMRI signals is maintained under experimental suppression of end-tidal carbon dioxide variations, suggesting that respiratory-driven fluctuations in arterial CO2 accompanying arousal cannot fully explain the origin of these signals in the brain. These findings suggest that the global fMRI signal is a substantial component of the arousal response governed by the autonomic nervous system. Bolt, Taylor, et al. “Autonomic physiological coupling of the global fMRI signal.” Nature Neuroscience (2025): 1-9.