Evidence of Altered Functional Connectivity at Rest in the Writing Network of Children with Dyslexia

Claire Gosse,Marie Van Reybroeck,Laurence Dricot

doi:10.3390/brainsci12020243

Abstract

Aim. Handwriting abilities in children with dyslexia (DYS) are not well documented in the current literature, and the presence of graphomotor impairment in addition to spelling impairment in dyslexia is controversial. Using resting-state functional connectivity (RSFC), the present study aims to answer the following question: are there markers of graphomotor impairment at rest in DYS children? Method. The participants were children with DYS and typically developing (TD) children (n = 32) from French-speaking primary schools (Mage = 9.3 years). The behavioural evaluation consisted of spelling and handwriting measures. Participants underwent a resting-state fMRI scan. Results. Analyses of RSFC focused on a brain region responsible for graphomotor processes—the graphemic/motor frontal area (GMFA). The RSFC between the GMFA and all other voxels of the brain was measured. Whole-brain ANOVAs were run to compare RSFC in DYS and TD children. The results demonstrated reduced RSFC in DYS compared to TD between the GMFA and brain areas involved in both spelling processes and motor-related processes. Conclusions. For the first time, this study highlighted a disruption of the writing network in DYS. By identifying functional markers of both spelling and handwriting deficits at rest in young DYS participants, this study supports the presence of graphomotor impairment in dyslexia.

Highlights

Developmental dyslexia is a neurobiological disorder characterised by deviant literacy development, [1,2,3,4,5] affecting approximately 10% of the French-speaking population, the language of the present study
Our results reveal that the left graphemic/motor frontal area (GMFA), a region that is specialised in graphomotor processes, has reduced connectivity with regions that are recruited during reading and spelling for both phonological and lexical processes in DYS children [64]
Our results revealed that the left GMFA had reduced connectivity with brain areas of the limbic system in DYS children compared to typically developing (TD) children, which is responsible for emotion and behaviour regulation

Summary

Introduction

Developmental dyslexia is a neurobiological disorder characterised by deviant literacy development, [1,2,3,4,5] affecting approximately 10% of the French-speaking population, the language of the present study. The symptoms of dyslexia occur despite normal intelligence, adequate education and the absence of sensory deficits, and they persist across a lifespan. In addition to reading impairment, DYS children have a severe and persistent impairment in spelling, which remains the most visible symptom of dyslexia in adults [6,7]. Past research has repeatedly demonstrated that DYS children struggle with all writing activities that are carried out every day in school, such as copying tasks [8,9], dictation tasks [10] and text composition [11]. Despite the importance of mastering writing and the severity and persistence of DYS-related writing impairment, current research on dyslexia focuses substantially more on reading difficulties than on writing difficulties. A gap in the literature concerns the presence of graphomotor difficulties in children with dyslexia in addition to their spelling impairment

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