| Abstrakt: |
Objective: Although human brain appears to be macroscopically symmetrical, it is known that the connectivity of the human brain varies to a certain extent between the right and left hemispheres. In this study, we aimed to investigate whether the thicknesses of the major cortico-cortical association tracts differ between hemispheres. Methods: Diffusion images of 106 randomly selected subjects from the Human Connectome Project (HCP) dataset were processed using DSI Studio, fiber counts of 17 major association tracts were extracted via deterministic tractography. Mean fiber counts were compared between two hemispheres. Results: The difference between two hemispheres was statistically significant in 15 of the 17 tracts examined. The five tracts with the greatest difference between fiber counts were arcuate fasciculus, frontal aslant tract, cingulum frontal parietal, superior longitudinal fasciculus 1st and 2nd bundles. Arcuate fasciculus (80214± 6561 vs 41524±5528, p<0.000001), cingulum frontal parahippocampal (16812±2529 vs 14641±2252, p<0.000001), frontal aslant (54453±4579 vs 29757±2396, p<0.000001), middle longitudinal fasciculus (24983±4015 vs 17900±1953, p<0.000001), uncinate fasciculus (22476±2053 vs 18949±1952, p<0.000001) and vertical occipital fasciculus (12624±1346 vs 8874±1169, p< 0.000001) fiber counts were higher in left hemisphere whereas cingulum frontal parietal (24835±3294 vs 48943±4499, p<0.000001), cingulum parahippocampal parietal (13469±1534 vs 18253±1976, p<0.000001), cingulum paraolfactory (8800±912 vs 18603±2478, p<0.000001), inferior frontooccipital fasciculus (104115±9432 vs 115823±10351, p<0.000001), inferior longitudinal fasciculus (82324±7717 vs 95698±8404, p<0.000001), parietal aslant (24590±2485 vs 32405±3312, p<0.000001), superior longitudinal fasciculus 1st bundle (27936±3243 vs 34744±4769, p <0.000001), 2nd bundle (67590±5188 vs 88174±10808, p< 0.000001), 3rd bundle (22864±2595 vs 39729±2595, p <0.000001) fiber counts were higher in right hemisphere. There was no difference between two hemispheres in cingulum parahippocampal and extreme capsule fiber counts. Conclusion: There are significant differences between hemispheres in terms of thickness of the major association tracts. These differences in fiber counts point to the structural connectivity basis of hemispheric asymmetry and lateralization in the human brain. [ABSTRACT FROM AUTHOR] |
