Resting-state Functional Connectivity During Controlled Respiratory Cycles Using Functional Magnetic Resonance Imaging

This study aimed to assess the effect of controlled mouth breathing during the resting state using functional magnetic resonance imaging (fMRI).

Eleven subjects participated in this experiment in which the controlled “Nose” and “Mouth” breathings of 6 s respiratory cycle were performed with a visual cue at 3T MRI. Voxel-wise seed-to-voxel maps and whole-brain region of interest (ROI)-to-ROI connectome maps were analyzed in both “Nose>Mouth” and “Mouth>Nose” contrasts.

As a result, there were more connection pairs in the “Mouth” breathing condition, i.e., 14 seeds and 14 connecting pairs in the “Mouth>Nose” contrast, compared to 7 seeds and 4 connecting pairs in the “Nose>Mouth” contrast (false discovery rate [FDR] of P<0.05).

The present study demonstrated that mouth breathing with controlled respiratory cycles could significantly induce alterations in functional connectivity in the resting-state network, suggesting that it can differently affect resting brain function; in particular, the brain can hardly rest during mouth breathing, as opposed to conventional nasal breathing.