Microstructural integrity of the dual-stream fiber pathways significantly affects language performance of individuals...

The critical role of subcortical fiber pathways in mediating interregional communication within cortical language networks is widely acknowledged. However, the relationship between their structural integrity and language impairment following brain injury remains incompletely understood. This knowledge gap has motivated sustained efforts to systematically examine how the microstructural integrity of these pathways influences the phenotypic manifestations of linguistic deficits in individuals with aphasia. In this study, we quantitatively evaluated the microstructural properties of eight major language-related neural tracts-including bilateral dorsal/ventral pathways, the frontal aslant tracts, and the extreme capsule fasciculi-in a cohort of sixty-eight patients with subacute post-stroke aphasia (PSA) using diffusion tensor imaging (DTI). Hemispheric differences were observed in the diffusion indices of the examined tracts. Correlation analyses revealed significant associations between diffusion measures in these tracts and performance across multiple language subdomains, including aphasia severity, spontaneous speech, comprehension, repetition, naming, and fluency. Our findings highlight the importance of microstructural integrity within left-hemispheric neural tracts for language performance and provide supplementary evidence supporting interactions between the left dorsal and ventral fiber pathways during language processing in the early post-stroke period.