title: Resting-state functional connectivity in late-life depression: higher global connectivity and more long distance connections.
abstract: Functional magnetic resonance imaging recordings in the resting-state (RS) from the human brain are characterized by spontaneous low-frequency fluctuations in the blood oxygenation level dependent signal that reveal functional connectivity (FC) via their spatial synchronicity. This RS study applied network analysis to compare FC between late-life depression (LLD) patients and control subjects. Raw cross-correlation matrices (CM) for LLD were characterized by higher FC. We analyzed the small-world (SW) and modular organization of these networks consisting of 110 nodes each as well as the connectivity patterns of individual nodes of the basal ganglia. Topological network measures showed no significant differences between groups. The composition of top hubs was similar between LLD and control subjects, however in the LLD group posterior medial-parietal regions were more highly connected compared to controls. In LLD, a number of brain regions showed connections with more distant neighbors leading to an increase of the average Euclidean distance between connected regions compared to controls. In addition, right caudate nucleus connectivity was more diffuse in LLD. In summary, LLD was associated with overall increased FC strength and changes in the average distance between connected nodes, but did not lead to global changes in SW or modular organization.
authors: School of Computing Science, Newcastle University Newcastle upon Tyne, UK.
authors: Iwo Jerzy
authors: IJ
authors: Bohr
authors: Eva
authors: E
authors: Kenny
authors: Andrew
authors: A
authors: Blamire
authors: John T
authors: JT
authors: O'Brien
authors: Alan J
authors: AJ
authors: Thomas
authors: Jonathan
authors: J
authors: Richardson
authors: Marcus
authors: M
authors: Kaiser
keywords: aging; default mode network; functional connectivity; functional magnetic resonance; graph theory; late-life depression; network analysis; resting-state