Multiplex core-periphery organization of the human connectome

What is the core of the human brain is a fundamental question that hasbeen mainly addressed by studying the anatomical connections betweendifferently specialized areas, thus neglecting the possiblecontributions from their functional interactions. While many methods areavailable to identify the core of a network when connections betweennodes are all of the same type, a principled approach to define the corewhen multiple types of connectivity are allowed is still lacking. Here,we introduce a general frame-work to define and extract thecore-periphery structure of multi-layer networks by explicitly takinginto account the connectivity patterns at each layer. We first validateour algorithm on synthetic networks of different Size and density, andwith tunable overlap between the cores at different layers. We then useour method to merge information from structural and functional brainnetworks, obtaining in this way an integrated description of the core ofthe human connectome. Results confirm the role of the main knowncortical and subcortical hubs, but also suggest the presence of newareas in the sensori-motor cortex that are crucial for intrinsic brainfunctioning. Taken together these findings provide fresh evidence on afundamental question in modern neuroscience and offer new opportunitiesto explore the mesoscale properties of multimodal brain networks.