Abstract
Background and PurposeLittle is known about the interactions between the default mode network (DMN) subregions in relapsing-remitting multiple sclerosis (RRMS). This study used diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) to examine alterations of long white matter tracts in paired DMN subregions and their functional connectivity in RRMS patients.MethodsTwenty-four RRMS patients and 24 healthy subjects participated in this study. The fiber connections derived from DTI tractography and the temporal correlation coefficient derived from rs-fMRI were combined to examine the inter-subregion structural-functional connectivity (SC-FC) within the DMN and its correlations with clinical markers.ResultsCompared with healthy subjects, the RRMS patients showed the following: 1) significantly decreased SC and increased FC in the pair-wise subregions; 2) two significant correlations in SC-FC coupling patterns, including the positive correlation between slightly increased FC value and long white matter tract damage in the PCC/PCUN-MPFC connection, and the negative correlations between significantly increased FC values and long white matter tract damage in the PCC/PCUN-bilateral mTL connections; 3) SC alterations [log(N track) of the PCC/PCUN-left IPL, RD value of the MPFC-left IPL, FA value of the PCC/PCUN-left mTL connections] correlated with EDSS, increases in the RD value of MPFC-left IPL connection was positively correlated to the MFIS; and decreases in the FA value of PCC/PCUN-right IPL connection was negatively correlated with the PASAT; 4) decreased SC (FA value of the MPFC-left IPL, track volume of the PCC/PCUN-MPFC, and log(N track) of PCC/PCUN-left mTL connections) was positively correlated with brain atrophy.ConclusionsIn the connections of paired DMN subregions, we observed decreased SC and increased FC in RRMS patients. The relationship between MS-related structural abnormalities and clinical markers suggests that the disruption of this long-distance “inter-subregion” connectivity (white matter) may significantly impact the integrity of the network's function.
Highlights
Pathological [1,2,3,4] and neuroimaging [5,6,7] studies have demonstrated the widespread involvement of the gray matter and white matter of the brain in multiple sclerosis (MS)
default mode network (DMN) maps revealed a typical spatial pattern in both the patient and control groups (P,0.05, FDR corrected), and six subregions were extracted from the union of the DMN maps of two groups (Figure 1)
We found two significant correlations between the functional connectivity (FC) and structural connectivity (SC) measures: slightly increased FC value was positively correlated with long white matter tract damage in the PCC/PCUN-medial prefrontal cortex (MPFC) connection, and significantly increased FC values were negatively correlated with long white matter tract damage in the PCC/PCUN-bilateral medial temporal lobes (mTLs) connections
Summary
Pathological [1,2,3,4] and neuroimaging [5,6,7] studies have demonstrated the widespread involvement of the gray matter and white matter of the brain in multiple sclerosis (MS). The structures has been considered as the underlying foundation of functional change. It is controversial in the relationship between the cerebral structure and function or clinical function [12,13,14]. Little is known about the interactions between the default mode network (DMN) subregions in relapsing-remitting multiple sclerosis (RRMS). This study used diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) to examine alterations of long white matter tracts in paired DMN subregions and their functional connectivity in RRMS patients
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