Widespread Autonomic Physiological Coupling Across the Brain-Body Axis.

Area of Science:

• Neuroscience
• Physiology
• Systems Biology

Background:

• The brain constantly monitors the body's internal state through visceral signals.
• Neural, hemodynamic, and physiological signals show complex interdependencies.

Purpose of the Study:

• To identify a unifying spatiotemporal pattern of brain-body co-fluctuations.
• To investigate the role of the global fMRI signal in physiological arousal.

Main Methods:

• Analysis of resting-state fMRI data across multiple samples and acquisition sequences.
• Examination of low-frequency (0.01-0.1 Hz) signal co-fluctuations.
• Elicitation of brain-body signals through induced arousal (deep breathing, sensory stimuli) and natural events (sleep EEG).
• Experimental manipulation of end-tidal carbon dioxide (PETCO2) to assess its influence.

Main Results:

• A single spatiotemporal pattern characterizes widespread brain-body co-fluctuations.
• These co-fluctuations link resting-state global fMRI signals with neural activity and autonomic signals (cardiovascular, pulmonary, etc.).
• The same pattern is observed during induced arousal and spontaneous sleep events.
• Global fMRI signal structure persists even when PETCO2 variations are suppressed, decoupling it from respiratory-driven CO2 changes.

Conclusions:

• The global fMRI signal is a key component of the brain's arousal response.
• These findings highlight the autonomic nervous system's role in governing brain-body communication.
• This research provides a unified framework for understanding brain-body interactions.