The involvement of the right hemisphere (RH) in language, and especially after aphasia resulting from left hemisphere (LH) lesions, has been recently highlighted. The present study investigated white matter structure in the right hemisphere of 25 chronic post-stroke aphasic patients after LH lesions in comparison with 24 healthy controls, focusing on the four cortico-cortical tracts that link posterior parietal and temporal language-related areas with Broca’s region in the inferior frontal gyrus of the LH: the Superior Longitudinal Fasciculi II and III (SLF II and SLF III), the Arcuate Fasciculus (AF), and the Temporo-Frontal extreme capsule Fasciculus (TFexcF). Additionally, the relationship of these RH white matter tracts to language performance was examined. The patients with post-stroke aphasia in the chronic phase and the healthy control participants underwent diffusion tensor imaging (DTI) examination. The aphasic patients were assessed with standard aphasia tests. The results demonstrated increased axial diffusivity in the RH tracts of the aphasic patients. Patients were then divided according to the extent of the left hemisphere white matter loss. Correlations of language performance with radial diffusivity in the right hemisphere homologues of the tracts examined were demonstrated for the TFexcF, SLF III and AF in the subgroup with limited damage to the LH language networks and only with the TFexcF in the subgroup with extensive damage. The results argue in favor of compensatory roles of the right hemisphere tracts in language functions when the LH networks are disrupted.

中文翻译：

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左半球语言束受损后，右半球白质束在慢性失语症患者中的作用

最近已经强调了右半球（RH）的语言参与，尤其是在左半球（LH）病变导致失语之后。本研究调查了LH病变后的25位慢性卒中后慢性失语症患者右半球的白质结构，与24名健康对照者进行了比较，重点研究了连接后顶叶和颞叶语言相关区域与Broca区域的四个皮层皮质道。 LH的额下回中：上纵向筋膜II和III（SLF II和SLF III），弓形筋膜（AF）和颞额顶囊筋膜（TFexcF）。此外，还检查了这些RH白质谱与语言表现的关系。慢性期卒中后失语症患者和健康对照组的参与者进行了弥散张量成像（DTI）检查。对失语症患者进行标准的失语症检查。结果表明，失语症患者在RH区域的轴向扩散性增加。然后根据左半球白质丢失的程度对患者进行分类。对于TFexcF，SLF III和AF的亚组，对LH语言网络的损害有限，而对亚组中的TFexcF，只有在广泛受损的情况下，语言性能与所测听音的右半球同源物的径向扩散性相关。结果证明，当LH网络被破坏时，右半球区域在语言功能中具有补偿作用。