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Abstract

To estimate white matter interregional axonal pathways and to infer left and right common anatomical network properties, obtaining global and local measures that allow us to evaluate structural network (dis)similarities between hemispheres, high-angular resolution DW-MRI datasets were acquired in 11 right-handed healthy subjects. T2-weighted images were parcellated into 90 gray matter structures. 3 axonal connectivity values were estimated using 3 fiber tractography algorithms: FSL, PICo, and a graph-based tractography algorithm. Whole-brain network was segmented into left and right hemispheric networks and analyzed in a graph framework: anatomic regions representing nodes and connections obtained from tractography representing arcs. Topological parameters of global efficiency, local efficiency, interconnectivity and betweenness centrality were extracted. Lateralization index was computed for these measures. We found significant differences between right and left hemispheric networks at a hemispheric level for the efficiency and interconnectivity metrics. Also, 21 pairs of human homolog regions were found lateralized according to centrality (15 leftward 6 rightward). These indicate either that the right hemisphere is, at the whole-hemisphere level, more efficient and interconnected and also that the left hemisphere presents more central or indispensable regions for the whole-brain structural network. A greater left hemisphere functional specialization could lead to its apparently ‘worse’ general structural organization. Results are in line with the fact that the left hemisphere has a leading role for highly demanding specific process (e.g.language and motor actions), whereas the right hemisphere has a leading role for more general process (e.g.integration tasks).