Contrasting brain patterns of writing-related DTI parameters, fMRI connectivity, and DTI–fMRI connectivity correlations in children with and without dysgraphia or dyslexia

Abstract

Based on comprehensive testing and educational history, children in grades 4–9 (on average 12 years) were diagnosed with dysgraphia (persisting handwriting impairment) or dyslexia (persisting word spelling/reading impairment) or as typical writers and readers (controls). The dysgraphia group (n = 14) and dyslexia group (n = 17) were each compared to the control group (n = 9) and to each other in separate analyses. Four brain region seed points (left occipital temporal gyrus, supramarginal gyrus, precuneus, and inferior frontal gyrus) were used in these analyses which were shown in a metaanalysis to be related to written word production on four indicators of white matter integrity and fMRI functional connectivity for four tasks (self-guided mind wandering during resting state, writing letter that follows a visually displayed letter in alphabet, writing missing letter to create a correctly spelled real word, and planning for composing after scanning on topic specified by researcher). For those DTI indicators on which the dysgraphic group or dyslexic group differed from the control group (fractional anisotropy, relative anisotropy, axial diffusivity but not radial diffusivity), correlations were computed between the DTI parameter and fMRI functional connectivity for the two writing tasks (alphabet and spelling) by seed points. Analyses, controlled for multiple comparisons, showed that (a) the control group exhibited more white matter integrity than either the dysgraphic or dyslexic group; (b) the dysgraphic and dyslexic groups showed more functional connectivity than the control group but differed in patterns of functional connectivity for task and seed point; and (c) the dysgraphic and dyslexic groups showed different patterns of significant DTI–fMRI connectivity correlations for specific seed points and written language tasks. Thus, dysgraphia and dyslexia differ in white matter integrity, fMRI functional connectivity, and white matter–gray matter correlations. Of clinical relevance, brain differences were observed in dysgraphia and dyslexia on written language tasks yoked to their defining behavioral impairments in handwriting and/or in word spelling and on the cognitive mind wandering rest condition and composition planning.

Idea units in notes and summaries for read texts by keyboard and pencil in middle childhood students with specific learning disabilities: Cognitive and brain findings

“…Finally, this research supplements prior research showing that typically developing readers and writers differ in structural and functional connectivity on handwriting and spelling tasks and planning for text-level composing [53]. Only those with dyslexia with and without dysgraphia or with dysgraphia were included in the current study, which showed response to instruction in that correlations between brain connectivity and proportion of ideas units in notes and summaries increased after specialized instruction.…”

Computerized writing and reading instruction for students in grades 4–9 with specific learning disabilities affecting written language

“…Impairment was defined as below −2/3 SD on relevant measures. For brain evidence that control SLD groups differ from each other and from controls, see Richards et al (in press) and Berninger et al (2015).…”

Brain Connectivity Associated with Cascading Levels of Language

“…The amount of connectivity detected with other brain regions from a given seed, even after controlling for multiple comparisons [7], may be surprising to some. The brain atlas often used in connectome research [8-11] and also used in this fMRI connectivity study—the Jülich histological (cyto-and myeloarchitectonic) atlas [12,13] provides much more fine-grained detail and increases the number of potential connections compared to prior atlases with fewer locations within regions.…”