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

Introduction: this study aimed to assess the effect of controlled mouth breathing during the resting state using functional magnetic resonance imaging (fmri). methods: 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. results: 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). conclusion: 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.