Rodrigo S, Naggara O, Oppenheim C, Golestani N, Poupon C, Cointepas Y, Mangin J F, Le Bihan D, Meder J F
Département d'Imagerie Morphologique et Fonctionnelle, Faculté de Médecine, Université Paris-Descartes, Centre Hospitalier Sainte-Anne, Paris, France.
AJNR Am J Neuroradiol. 2007 Sep;28(8):1526-31. doi: 10.3174/ajnr.A0584.
Our aim was to improve our understanding of the subinsular white matter microstructural asymmetries in healthy right-handed subjects. Structural brain asymmetries could be related to functional asymmetries such as hemisphere language dominance or handedness. Besides the known gray matter asymmetries, white matter asymmetries could also play a key role in the understanding of hemispheric specialization, notably that of language.
White matter asymmetries were studied by diffusion tensor imaging at 1.5T (41 diffusion-gradient directions; b-value set to 700 s/mm(2); matrix, 128(2); in-plane resolution, 1.875 x 1.875 mm; section thickness, 2.0 mm) and fiber tracking (BrainVISA software). The main white matter bundles passing through the subinsular area were segmented, and fractional anisotropy (FA) was measured along each of the segmented bundles.
In line with published results, we found an asymmetry of the arcuate fasciculus and the subinsular white matter, namely left-greater-than-right FA in right-handed controls. Furthermore, by segmenting major tracts coursing through this region, we showed that the subinsular portions of the uncinate fasciculus (UF) and the inferior occipitofrontal fasciculus (IOF) contribute to this FA asymmetry. Those tracts have been reported to be likely implicated in the language network.
Because the left hemisphere hosts language functions in most right-handers, the significant leftward asymmetry observed within the arcuate fasciculus, the subinsular part of the UF and IOF may be related to the hemispheric specialization for language.
我们的目的是加深对健康右利手受试者岛叶下白质微结构不对称性的理解。大脑结构不对称可能与功能不对称有关，如半球语言优势或利手。除了已知的灰质不对称外，白质不对称在理解半球特化，尤其是语言特化方面也可能起关键作用。
采用1.5T的扩散张量成像（41个扩散梯度方向；b值设定为700 s/mm(2)；矩阵，128(2)；平面分辨率，1.875×1.875 mm；层厚，2.0 mm）和纤维追踪（BrainVISA软件）研究白质不对称性。对穿过岛叶下区域的主要白质束进行分割，并沿每个分割束测量分数各向异性（FA）。
与已发表的结果一致，我们发现弓形束和岛叶下白质存在不对称性，即在右利手对照中左侧FA大于右侧。此外，通过分割穿过该区域的主要束，我们表明钩束（UF）和枕颞额下束（IOF）的岛叶下部分促成了这种FA不对称。据报道，这些束可能与语言网络有关。
由于在大多数右利手者中左半球负责语言功能，在弓形束、UF和IOF的岛叶下部分观察到的显著向左不对称可能与语言的半球特化有关。
