Synchronization within, and interactions between, the default mode and dorsal attention networks in relapsing-remitting multiple sclerosis

Abstract

Muhua Huang,1,2 Fuqing Zhou,1,2 Lin Wu,1,2 Bo Wang,1,2 Hui Wan,3 Fangjun Li,3 Xianjun Zeng,1,2 Honghan Gong1,2 1Department of Radiology, The First Affiliated Hospital, Nanchang University, Nanchang, People’s Republic of China; 2Neuroradiology Laboratory, Jiangxi Province Medical Imaging Research Institute, Nanchang, People’s Republic of China; 3Department of Neurology, The First Affiliated Hospital, Nanchang University, Nanchang, People’s Republic of China Background and purpose: The effects of the interactions between the default mode network (DMN) and the dorsal attention network (DAN), which present anticorrelated behaviors, in relapsing-remitting multiple sclerosis (RRMS) are poorly understood. This study used resting-state functional connectivity (FC) and the Granger causality test (GCT) to examine changes in the undirected and effective functional network connectivity (FNC) between the two networks during the remitting phase in RRMS patients.Patients and methods: Thirty-three patients experiencing a clinically diagnosed remitting phase of RRMS and 33 well-matched healthy control subjects participated in this study. First, an independent component (IC) analysis was performed to preprocess the functional magnetic resonance imaging data and select resting-state networks. Then, an FNC analysis and the GCT were combined to examine the temporal correlations between the ICs of the DMN and DAN and to identify correlations with clinical markers.Results: Compared with the healthy subjects, the RRMS patients in the remitting phase showed the following: 1) significantly decreased FC within the DAN in the postcentral gyrus and decreased FC within the DMN in several regions except the parahippocampal gyrus, where increased FC was observed; 2) a relatively stable interaction between the two anticorrelated networks as well as a driving connectivity from the DAN to DMN (IC15); and 3) significantly positive correlations between the connectivity coefficient of the right superior temporal gyrus and the Modified Fatigue Impact Scale score (ρ = 0.379, p = 0.036).Conclusion: Adaptive mechanisms that maintain stable interactions might occur between the DMN and DAN during the remitting phase in RRMS patients. Keywords: default mode network, dorsal attention network, multiple sclerosis, resting-state functional MRI, Granger causality test, anticorrelation

Keywords

• default mode network
• dorsal attention network
• multiple sclerosis
• resting-state functional MRI
• Granger causality test
• anticorrelation.