Age-related changes of the representative modular structure in the brain

Describing the changes of modularity in different clinical states can help to understand the alterations of the global processing mechanisms. In the current study we applied the modularity in a local scale. The method is based on measuring the decrease of the modularity caused by shifting a node from its own module to another module. On one hand local modularity measures the influence of a node in the formation of the modular organization. On the other hand we evaluated differences in the community membership of the nodes between the modular structures of two groups. The method was tested on resting-state fMRI data of 20 young and 20 elderly subjects. Increased local modularity of the occipital module was found in the young, which is in line with the previously reported increased segregation of the visual cortex in the young. Regions of the dorsal attention network were characterized with an increased local modularity in the elderly which suggest that these regions preserve the modular structure in advanced age. These findings indicate that applying the modularity on a local scale is a promising biomarker for detecting differences between age groups.

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