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Major white matter tracts underlying language processing-a tractography study
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Poster A53 in Poster Session A - Sandbox Series, Thursday, October 24, 10:00 - 11:30 am, Great Hall 4
This poster is part of the Sandbox Series.
Qingchun WANG1, Yongkun GUO2, Fang WANG2, Yang LIU2, Xinjun WANG*2,3, Wai-Ting SIOK*1; 1The Hong Kong Polytechnic University, Hong Kong SAR, China, 2The Fifth Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China, 3The Third Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
Aphasia is a neurological disorder that typically results from brain damage, causing significant language deficits due to lesions in cortical regions or subcortical white matter tracts. Recently, the structural connectivity of the brain has drawn intensive attention, as its potential to facilitate language recovery. Although many white matter tracts have been proposed to participate in language processing, these pathways have not been fully examined in Chinese aphasic patients. In this study, we present five Chinese aphasic patients with language disorders resulting from unilateral left-hemisphere lesions. These patients were recruited from a local hospital in Mainland China. Ten healthy participants, matched for age, gender, language and educational background were recruited as the control group. Aphasia was diagnosed using the Chinese Rehabilitation Research Center Standard Aphasia Examination (CRRCAE), a widely used clinical tool in Mainland China. Language abilities, including speech comprehension, speech production, reading comprehension, writing, repetition, and reading aloud, were assessed by the CRRCAE, generating standardized scores based on correct items. Neuroimaging examinations including anatomical magnetic resonance imaging (MRI) and diffusion MRI were performed on a 3.0T Philips Ingenia scanner with identical scanning sequences for all participants. Behavioral measurements revealed significant language deficits in all tested linguistic domains for aphasic patients. Diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD), were extracted for each target white matter tract. An atlas-based diffusion metrics extraction method was employed to analyze indices of hypothesized language-related white matter tracts, including the arcuate fasciculus (AF), superior longitudinal fasciculus (SLF) I-III, inferior longitudinal fasciculus (ILF), inferior frontal-occipital fasciculus (IFOF), uncinate fasciculus (UF), middle longitudinal fasciculus (MdLF), and corticospinal tract (CST) bilaterally. Diffusion metrics were used to examine intergroup differences and the association between white matter integrity and language performance using partial correlation. Consistent with previous neuroimaging studies, aphasic patients exhibited significantly lower mean FA values in most target fiber tracts in the left hemisphere, except for the SLF_I and CST. Similar patterns were observed for MD and RD, with patients showing significantly higher values in left hemisphere tracts except for the first segment of the SLF and CST. Correlation analyses showed that FA measures for the left AF were significantly related to reading comprehension scores (p < 0.05). FA values in the left IFOF were also significantly correlated with reading comprehension (p < 0.05), and left SLF_III was significantly associated with speech production (p < 0.05). To comprehensively examine macro- and microstructural integrity, we reconstructed the left AF, left IFOF, and left SLF_III using probabilistic tractography, revealing evident fiber loss in aphasic patients. Our findings support the involvement of white matter tracts in language processing. The results from diffusion metrics analyses confirmed reduced integrity in language-related fiber tracts in aphasic patients. Correlation analyses highlighted the functional roles of the left AF, SLF III, and IFOF in spoken and written language. Additionally, we provided new evidence for the potential contribution of the left IFOF in Chinese reading. This study also detailed individual deficit patterns of each aphasic patient using tractography.
Topic Areas: Disorders: Acquired,