Structural disconnection, known to occur in multiple sclerosis (MS), contributes to network resting-state functional connectivity (rsFC) changes in MS, a recent study found. Furthermore, community isolation is responsible for elevated network functional connectivity. Given the known dependence of rsFC on underlying structural connectivity (SC), researchers examined an alternative hypothesis: that topographical changes in SC, specifically particular patterns of disconnection, contribute to increased network rsFC. They obtained measures of rsFC using fMRI and SC using probabilistic tractography in 50 healthy and 28 MS subjects. They found:

• Altering the model by introducing structural disconnection patterns observed in the MS subjects with high network rsFC generates simulations with high rsFC as well, suggesting that disconnection itself plays a role in producing high network functional connectivity.
• In MS subjects with high network rsFC, there was a preferential disconnection between the relevant network and wider system.
• As observed empirically, simulated network rsFC increases with removal of connections bridging a community with the remainder of the brain.