Study Objectives: Structural and functional brain changes may contribute to neural dysfunction in patients with obstructive sleep apnea(OSA).However,the effect of OSA on resting-state brain activity has not been established.The objective of this study was to investigate alterations in resting-state functional connectivity(rsFC)of the common brain networks in OSA patients and their relationships with changes in grey matter volume(GMV)in the corresponding brain regions.Designs: Resting-state functional and structural MRI data were acquired from OSA patients and control subjects.Seven brain networks were identified by independent component analysis.The rsFC in each network was compared between groups and the GMV of brain regions with significant differences in rsFC was also compared.Patients and Participants: Twenty-four male patients with untreated OSA and 21 matched healthy controls.Measurements and Results: OSA specifically affected the cognitive and sensorimotor-related brain networks but not the visual and auditory networks.The medial prefrontal cortex and left dorsolateral prefrontal cortex(DLPFC)showed decreased rsFC and GMV in OSA patients,suggesting structural and functional deficits.The right DLPFC and left precentral gyrus showed decreased rsFC and unchanged GMV,suggesting a functional deficit.The right posterior cingulate cortex demonstrated increased rsFC and unchanged GMV,suggesting functional compensation.In OSA patients,the rsFC of the right DLPFC was negatively correlated with the apnea-hypopnea index.Conclusions: OSA specifically affects rsFC in cognitive and sensorimotor-related brain networks,which may be related to the impaired cognitive and motor functions in these patients.