Recent work has revealed that bvFTD syndrome, like typical AD, reflect the progressive degeneration of a specific large-scale network, the “salience network”.6,84 This network is involved in processing emotionally significant stimuli and is inversely correlated with the DMN in task-free settings,28 leading Seeley and colleagues to predict that bvFTD and AD would feature divergent network connectivity patterns.85 This hypothesis was subsequently tested using task-free fMRI and ICA analysis of the DMN and salience networks in patients with bvFTD and AD.58 The study identified divergent patterns in the two clinical groups, with reduced salience network connectivity and increased DMN connectivity in bvFTD and the opposite pattern in AD. In addition, reduced salience network connectivity in bvFTD patients was associated with greater disease severity.58 A score incorporating DMN and salience network connectivities better discriminated between the two clinical groups than did either network alone,58 suggesting that network-based patterns which are sensitive to decreases and increases may prove more specific to a given disease. Studies of structural connectivity in bvFTD support the disruption of specific frontal-temporal WM tracts, such as the bilateral uncinate
