title: Cortical functional connectivity networks in normal and spinal cord injured patients: Evaluation by graph analysis.
abstract: The present work aims at analyzing the structure of cortical connectivity during the attempt to move a paralyzed limb by a group of spinal cord injured (SCI) patients. Connectivity patterns were obtained by means of the Directed Transfer Function applied to the cortical signals estimated from high resolution EEG recordings. Electrical activity were estimated in normals (Healthy) and SCI patients on twelve regions of interest (ROIs) coincident with Brodmann areas. Degree distributions showed the presence of few cortical regions with a lot of outgoing connections in all the cortical networks estimated irrespectively of the frequency band investigated. For both of the groups (SCI and Healthy), bilateral cingulate motor area (CMA) acts as hub transmitting information flows. The efficiency index, allowed to assert the ordered properties of such estimated cortical networks in both populations. The comparison of such estimated networks with those obtained from random networks, elicited significant differences (P < 0.05, Bonferroni-corrected for multiple comparisons). A statistical comparison (ANOVA) between SCI patients and healthy subjects showed a significant difference (P < 0.05) between the local efficiency of their respective networks. For three frequency bands (theta 4-7 Hz, alpha 8-12 Hz, and beta 13-29 Hz) the higher value observed in the spinal cord injured population entails a larger level of internal organization and fault tolerance. This fact suggests a sort of compensative mechanism as local response to the alteration in their MIF areas, which is probably due to the indirect effects of the spinal injury.
authors.affiliation: Interdepartment Research Centre for Models and Information Analysis in Biomedical Systems, University La Sapienza, Rome, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: De Vico Fallani
authors.forename: Laura
authors.initials: L
authors.lastname: Astolfi
authors.forename: Febo
authors.initials: F
authors.lastname: Cincotti
authors.forename: Donatella
authors.initials: D
authors.lastname: Mattia
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Marciani
authors.forename: Serenella
authors.initials: S
authors.lastname: Salinari
authors.forename: Jurgen
authors.initials: J
authors.lastname: Kurths
authors.forename: Shangkai
authors.initials: S
authors.lastname: Gao
authors.forename: Andrzej
authors.initials: A
authors.lastname: Cichocki
authors.forename: Alfredo
authors.initials: A
authors.lastname: Colosimo
authors.forename: Fabio
authors.initials: F
authors.lastname: Babiloni
mesh_terms: D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D004569:Electroencephalography / Q000706:statistics & numerical data; D004576:Electromyography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007596:Joints / Q000502:physiology; D008297:Male; D008953:Models, Anatomic; D008959:Models, Neurological; D015233:Models, Statistical; D009068:Movement / Q000502:physiology; D009415:Nerve Net / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*