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. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was funded by NCCR Evolving Language with the Swiss National science Foundation Agreement #51NF40-180888, and the Fonds für wissenschaftliche Zwecke im Interesse der Heilung von psychischen Krankheiten. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All data stem from studies approved by the Ethics Commission of the Canton of Zurich. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors