title: Hubs of brain functional networks are radically reorganized in comatose patients.
abstract: Human brain networks have topological properties in common with many other complex systems, prompting the following question: what aspects of brain network organization are critical for distinctive functional properties of the brain, such as consciousness? To address this question, we used graph theoretical methods to explore brain network topology in resting state functional MRI data acquired from 17 patients with severely impaired consciousness and 20 healthy volunteers. We found that many global network properties were conserved in comatose patients. Specifically, there was no significant abnormality of global efficiency, clustering, small-worldness, modularity, or degree distribution in the patient group. However, in every patient, we found evidence for a radical reorganization of high degree or highly efficient "hub" nodes. Cortical regions that were hubs of healthy brain networks had typically become nonhubs of comatose brain networks and vice versa. These results indicate that global topological properties of complex brain networks may be homeostatically conserved under extremely different clinical conditions and that consciousness likely depends on the anatomical location of hub nodes in human brain networks.
authors.affiliation: Centre National de Recherche Scientifique, Grenoble Image Parole Signal Automatique, 38402 Grenoble, France. sophie.achard@gipsa-lab.grenoble-inp.fr
authors.forename: Sophie
authors.initials: S
authors.lastname: Achard
authors.forename: Chantal
authors.initials: C
authors.lastname: Delon-Martin
authors.forename: Petra E
authors.initials: PE
authors.lastname: Vértes
authors.forename: Félix
authors.initials: F
authors.lastname: Renard
authors.forename: Maleka
authors.initials: M
authors.lastname: Schenck
authors.forename: Francis
authors.initials: F
authors.lastname: Schneider
authors.forename: Christian
authors.initials: C
authors.lastname: Heinrich
authors.forename: Stéphane
authors.initials: S
authors.lastname: Kremer
authors.forename: Edward T
authors.initials: ET
authors.lastname: Bullmore
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D001930:Brain Injuries / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D003128:Coma / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology; D055815:Young Adult