Network alignment and similarity reveal atlas-based topological differences in structural connectomes

• Published in: bioRxiv
• Main Authors: Frigo, Matteo, Cruciani, Emilio, Coudert, David, Deriche, Rachid, Natale, Emanuele, Deslauriers-Gauthier, Samuel
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 16.12.2020; Cold Spring Harbor Laboratory
• Edition: 1.2
• Subjects: Magnetic resonance imaging; Nervous system; Neural networks; Neuroimaging; Neuroscience; brain network topology; Weisfeiler-Lehman; graph Jaccard index; brain parcellation; structural connectome; graph alignment
• ISSN: 2692-8205; 2692-8205
• DOI: 10.1101/2020.12.16.422501

Abstract Brain atlases are central objects in network neuroscience, where the interactions between different brain regions are modeled as a graph called connectome. In structural connectomes, nodes are parcels from a predefined cortical atlas and edges encode the strength of the axonal connectivity between regions measured via diffusion Magnetic Resonance Imaging (MRI) tractography. Herein, we aim at providing a novel perspective on the evaluation of brain atlases by modeling it as a network alignment problem, with the goal of tackling the following question: given an atlas, how robustly does it capture the network topology across different subjects? To answer such a question, we introduce two novel concepts arising as natural generalizations of previous ones. First, the graph Jaccard index (GJI), a graph similarity measure based on the well-established Jaccard index between sets; the GJI exhibits natural mathematical properties that are not satisfied by previous approaches. Second, we devise WL-align, a new technique for aligning connectomes obtained by adapting the Weisfeiler-Lehman (WL) graph-isomorphism test. We validated the GJI and WL-align on data from the Human Connectome Project database, inferring a strategy for choosing a suitable parcellation for structural connectivity studies. Code and data are publicly available. Competing Interest Statement The authors have declared no competing interest. Footnotes * {matteo.frigo{at}inria.fr,rachid.deriche{at}inria.fr,samuel.deslauriers-gauthier{at}inria.fr} * {emilio.cruciani{at}inria.fr,david.coudert{at}inria.fr,emanuele.natale{at}inria.fr} * https://osf.io/depux/