Sex Differences In Functional Connectivity Of Brain During Breathing Effort

Introduction or Background: Sex differences of neurological activity in brain on breathing effort without hypoxia are still unclear, although the differences have investigated on various external stimuli such as pain, emotion, fear and stress. Aims and Objectives: The aim of the study was to investigate sex difference of neurological activity and signaling in brain on breathing effort without hypoxia by brain functional magnetic resonance imaging (fMRI). Methods: Artificial breathing effort without hypoxia was prepared by an orifice device of mouthpiece type. Brain images with resting state were recorded with or without breathing effort for 7min by fMRI from 10 male and 10 female healthy volunteers. Dyspnea levels were assessed by modified Borgs scale. The area under the curves (AUC) of dyspnea levels and the data of fMRI were compared between male and female using by statistical software (JMP13, SAS Institute Inc. and FMRIB Software Library tools (Melodic ICA, dual regression, FSL Nets, respectively). Results: There was no difference in the AUC of dyspnea levels on breathing effort between male and female. Male had significant inter-network connectivity between the posterior cingulated gyrus and the front-orbital cortex, which corresponds to the Default mode network and Orbito-frontal network, whereas female showed significant inter-network connectivity between the posterior cingulated gyrus and the front-orbital cortex during breathing effort, corresponding to Sensory-motor network and Fronto-parietal network. Conclusion: Our study suggests sex difference that male may arouse the breathing effort as latent memories and female may feel intuitively it as external stimulation.