Widespread neural and autonomic system synchrony across the brain-body axis

The brain is closely attuned to visceral signals from the body's internal environment, as evidenced by the numerous associations between neural and peripheral physiological signals. This study describes a synchrony in the low-frequency range (0.01 - 0.1 Hz) between global brain hemodynamics, neural activity, and a host of autonomic signals spanning cardiovascular, pulmonary, exocrine and smooth muscle systems. We show that this brain-body synchrony can be captured by a single spatiotemporal pattern across fMRI, EEG and peripheral physiological signals in human subjects. These findings are replicated across several independent samples and data acquisition systems. Furthermore, this spatiotemporal pattern of brain-body synchrony is elicited by autonomic arousal in deep breathing, spontaneous K-complexes during sleep, and the delivery of intermittent sensory stimuli, as well as at rest. Further, we show that the spatial structure of global brain hemodynamics is maintained under experimental suppression of end-tidal carbon dioxide (PETCO2) variations, suggesting that respiratory-driven fluctuations in arterial CO2 accompanying arousal cannot explain the origin of these hemodynamic signals in the brain. These findings suggest that the origin of low-frequency global brain hemodynamics may be mediated by ascending arousal system projections, which modulate widespread neuronal activity as well as sympathetic vasoconstrictive effects on the cerebral vasculature. The prominence of this brain-body synchrony during deep breathing provides a mechanistic understanding of the positive health benefits of diaphragmatic breathing and may inform psychological therapeutic techniques for anxiety and stress. ### Competing Interest Statement The authors have declared no competing interest.