Article

Evaluation by graph analysis.
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.
CI - (copyright) 2007 Wiley-Liss, Inc.

Langue : ANGLAIS

Tiré à part : OUI