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Monica G. Chica, Keith A. Schneider; Hemispheric differences in the human lateral geniculate nucleus. Journal of Vision 2013;13(9):24. doi: https://doi.org/10.1167/13.9.24.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction Human brain asymmetry has been observed in previous studies and been related to a normal specialization of functional roles. Greater asymmetry between hemispheres has been associated with increased capabilities, such as enhanced processing auditory features, while smaller asymmetry has been linked to decreased capabilities, like dyslexia. Here we investigate hemispheric differences in the human lateral geniculate nucleus (LGN), a visual relay and control nucleus in the thalamus. Methods 26 subjects (13 controls and 13 subjects with dyslexia) were scanned with a Siemens Trio 3T MRI scanner. For each subject, 40 proton density weighted images were acquired with a resolution of 0.75 ´ 0.75 ´ 1 mm[sup]3[/sup]. The LGN were traced manually on these images by six independent observers. The median masks of right and left LGN of all subjects from each population were registered according to their centers of mass and averaged to create four probability maps. The left maps were then reflected for comparison with the right ones. Finally, we determined the principal axis of orientation of the LGN by fitting a plane through it that minimized the perpendicular distance from each point of the LGN to the plane. We then obtained the inclination angle of this plane in the subjects’ native spaces and compared the orientations between hemispheres. Results The difference in probability maps revealed morphological differences between the left and right LGN. The orientations of the LGN in the two hemispheres differed by 23.9 ± 5.4° (mean ± SEM), which was highly significant (p = .003). The right LGN was oriented more vertically in the coronal plane and the left more horizontally. There were no significant differences between dyslexics and controls. Conclusions We have observed previously unreported asymmetries in the morphology and orientation of the human LGN between hemispheres. The functional implications of these differences are unknown.
Meeting abstract presented at VSS 2013
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