en Cognitive Neuroscience Cognitive Neuroscience Original Original <div style="text-align: justify;"><strong>Introduction</strong>: This study aimed to assess the effect of controlled mouth breathing during the resting state using functional magnetic resonance imaging (fMRI).<br> <strong>Methods</strong>: Eleven subjects participated in this experiment in which the controlled &ldquo;Nose&rdquo; and &ldquo;Mouth&rdquo; 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 &ldquo;Nose>Mouth&rdquo; and &ldquo;Mouth>Nose&rdquo; contrasts.<br> <strong>Results</strong>: As a result, there were more connection pairs in the &ldquo;Mouth&rdquo; breathing condition, i.e., 14 seeds and 14 connecting pairs in the &ldquo;Mouth>Nose&rdquo; contrast, compared to 7 seeds and 4 connecting pairs in the &ldquo;Nose>Mouth&rdquo; contrast (false discovery rate [FDR] of P<0.05).<br> <strong>Conclusion</strong>: 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.</div> Respiratory rate, Functional connectivity, Functional MRI 855 864 http://bcn.iums.ac.ir/browse.php?a_code=A-10-2534-1&slc_lang=en&sid=1 Chan-A Park chaoskit21c@gmail.com 13700319475328460043486 13700319475328460043486 No Biomedical Engineering Research Center, Gachon University, Incheon, Republic of Korea. Yeong-Bae Lee yeongbaelee@gmail.com 13700319475328460043487 13700319475328460043487 No Department of Neurology, Gil Medical Center, Gachon University College of Medicine, Incheon, Republic of Korea. Chang-Ki Kang ckkang@gachon.ac.kr 13700319475328460043488 13700319475328460043488 Yes Department of Radiological Sciences, College of Health Sciences, Gachon University, Incheon, Republic of Korea.