Application of Multi Network Alignment Algorithms for Connectomes Study

A growing area in neurosciences is focused on the modeling and analysis the complex 1 system of connections in neural systems, i.e. the connectome. Here we focus on the representation of 2 connectomes by using graph theory formalisms. The human brain connectomes are usually derived 3 from neuroimages; the analyzed brains are co-registered in the image domain and brought to a 4 common anatomical space. An atlas is then applied in order to define anatomically meaningful 5 regions that will serve as the nodes of the network this process is referred to as parcellation. Recently, 6 it has been proposed to perform atlas-free random brain parcellation into nodes and align brains in 7 the network space instead of the anatomical image space to define network nodes of individual brain 8 networks. In the network domain, the question of comparison of the structure of networks arises. 9 Such question is tackled by modeling the comparison of brain network as a network alignment (NA) 10 problem. In this paper, we first defined the NA problem formally, then we applied three existing state 11 of the art of multiple alignment algorithms (MNA) on diffusion MRI-derived brain networks and we 12 compared the performances. The results confirm that MNA algorithms may be applied in cases of 13 atlas-free parcellation for a fully network-driven comparison of connectomes. 14