The structural covariance of reading-related brain regions in adults and children with typical reading skills and developmental dyslexia

Structural covariance (SC) is a promising approach for investigating brain organization within the domain of literacy and developmental disorders as it thought to reflect both functional and structural information. This study presents a first-of-its-kind exploration of SC in reading-related brain regions across different ages and reading abilities. Whole-brain SC analyses were conducted for six key regions of the reading network, including an anterior and posterior subdivision of the visual word form area (VWFA). We compared SC matrices of typically reading adults (N=134) and children (N=110), and between typically reading children and children with dyslexia (N=68). Our results showed significant associations between reading-related brain regions in typically reading adults. We observed significant SC between the posterior VWFA and the left occipital cortex, and between the anterior VWFA and the left superior temporal gyrus and left inferior frontal gyrus. Typical-reading adults and children did not differ significantly in SC. However, typically reading children demonstrated significantly higher SC between the inferior parietal lobule (IPL) and other reading-related brain regions than children with dyslexia. Our findings provide support for a functional and structural division of the VWFA and underscore the crucial role of the IPL in fluent reading.