Rich club organization supports a diverse set of functional network configurations

Abstract

Brain function relies on the flexible integration of a diverse set of segregated cortical/nmodules, with the structural connectivity of the brain being a fundamentally important factor/nin shaping the brain‟s functional dynamics. Following up on macroscopic studies showing the/nexistence of centrally connected nodes in the mammalian brain, combined with the notion that/nthese putative brain hubs may form a dense interconnected „rich club‟ collective, we/nhypothesized that brain connectivity might involve a rich club type of architecture to promote/na repertoire of different and flexibly accessible brain functions. With the rich club suggested/nto play an important role in global brain communication, examining the effects of a rich club/norganization on the functional repertoire of physical systems in general, and the brain in/nparticular, is of keen interest. Here we elucidate these effects using a spin glass model of/nneural networks for simulating stable configurations of cortical activity. Using simulations,/nwe show that the presence of a rich club increases the set of attractors and hence the diversity/nof the functional repertoire over and above the effects produced by scale free type topology/nalone. Within the networks‟ overall functional repertoire rich nodes are shown to be important/nfor enabling a high level of dynamic integrations of low-degree nodes to form functional/nnetworks. This suggests that the rich club serves as an important backbone for numerous co-/nactivation patterns among peripheral nodes of the network. In addition, applying the spin/nglass model to empirical anatomical data of the human brain, we show that the positive effects/non the functional repertoire attributed to the rich club phenomenon can be observed for the/nbrain as well. We conclude that a rich club organization in network architectures may be/ncrucial for the facilitation and integration of a diverse number of segregated functions.