Within- and across-network alterations in the default network and in visual networkpatients with somatic symptom disorder

Background: Somatic symptom disorders (SSDs) are common medical disorders characterized by various bio-logical, psychological, and social pathogenic factors. Little is known about the functional profiles associated with SSDs within and between brain networks.Methods: In this study, resting-state functional magnetic resonance imaging (fMRI) was assessed in 60 patients with SSD and 62 matched healthy controls (HCs). Independent component analysis (ICA) of 20 components was conducted and investigated for functional connectivity changes within and acrossnetworks between patients and controls. In addition, fractional amplitudes of low-frequency fluctuation (fALFF) were used to detect intensities of spontaneous functional activity in networks successfully separated by ICA.Results: The patients with SSD exhibited significantly increased functional connectivity (FC) in the left lingual gyruswithin thevisual network, and higher fALFF values in the cingulate cortex and precuneus within the default network. Furthermore, SSD patients showed significantly decreased FC between the default and visual networks.Conclusion: SSD is associated with significant changes within thevisual network, and the defaultnetwork, and decreased FC between the default network and visual network, which may indicate an imbalance within and between networks. These decouplings are likely associated with impaired perceptual and self-conscious inte-gration in those with the disease.