Fixel-based white matter atypicalities in relation to language impairment in children with developmental language disorder

Literature regarding white matter differences in children with developmental language disorder (DLD) has shown inconsistent results. Furthermore, relevance of neuroanatomical differences between typically developing children and children with DLD to language function has scarcely been investigated. Therefore, this study investigated white matter differences in children with DLD using fixel-based analysis, deriving fiber-specific metrics with increased biological specificity. Relations between fixel-based metrics showing group differences and behaviour were investigated for several language measures. <br>
Method. Dorsal (e.g., arcuate fasciculus) and ventral (e.g., uncinate fasciculus) language tracts and white matter of the cerebellar peduncles were modelled in 21 children with DLD and compared to that of 21 typically developing children between eight and 13 years of age. Children also completed an extensive language assessment, including overall language performance, vocabulary and word learning. Fixel-based metrics of the informative tracts (> 50 significant fixels in comparisons between groups) were regressed with the different language measures. <br>
Results. Children with DLD showed differences in fiber (density) cross-section in the uncinate, arcuate and superior longitudinal fasciculi, which were associated with overall language and/or vocabulary performance. Further, fixel metrics of the dorsal tracts were related to immediate recall of learned words. <br>
Discussion and conclusion. Our findings suggest that white matter differences in DLD could be associated with morphological differences in fiber bundle diameter or size. Further, atypical structural white matter properties may contribute to the observed language impairments. Our findings suggest that fixel-based analysis is a promising technique to detect fiber-specific differences in children with DLD.

关于发育性语言障碍（developmental language disorder, DLD）患儿脑白质差异的相关研究结论始终存在不一致性。此外，针对典型发育儿童与DLD患儿之间的神经解剖学差异与语言功能的关联性，目前鲜有研究涉足。因此，本研究采用基于fixel的分析（fixel-based analysis）方法，探究DLD患儿的脑白质差异，以获取具有更高生物学特异性的纤维特异性指标。同时，本研究还分析了呈现组间差异的fixel指标与多项语言行为测评结果之间的关联。<br>方法。本研究纳入21名DLD患儿与21名年龄介于8至13岁的典型发育儿童，对其背侧语言通路（如弓状束（arcuate fasciculus））、腹侧语言通路（如钩束（uncinate fasciculus））以及小脑脚（cerebellar peduncles）的脑白质进行建模，并开展组间对比。所有受试儿童均完成了全面的语言评估，涵盖整体语言表现、词汇能力与词汇学习能力三个维度。针对在组间比较中存在超过50个显著fixel的有效通路，将其fixel指标与各项语言测评结果进行回归分析。<br>结果。DLD患儿在钩束、弓状束与上纵束（superior longitudinal fasciculi）的纤维（密度）横截面积上存在显著差异，且该差异与整体语言表现及/或词汇能力显著相关。此外，背侧通路的fixel指标与习得词汇的即时回忆能力存在显著关联。<br>讨论与结论。本研究结果表明，DLD患儿的脑白质差异可能与纤维束直径或体积的形态学改变有关。进一步而言，异常的脑白质结构特性可能是导致所观察到的语言功能损伤的潜在机制。本研究结果同时证实，基于fixel的分析技术有望成为检测DLD患儿纤维特异性脑结构差异的可靠手段。