Children with dyslexia utilize both top-down and bottom-up networks equally in contextual and isolated word reading

Abstract

IntroductionExecutive functions (EF) include cognitive processes that support learning and reading. Children with dyslexia experience challenges with both reading and reading comprehension. The neurobiological support for EF deficits during reading comprehension, however, has yet to be defined. Here we aimed to identify the neural networks related to EF during a reading comprehension task focusing on top-down and bottom-up networks in children with dyslexia and typical readers (TR). MethodTwenty children with dyslexia and 19 TR aged 8–12 were scanned during a sentence comprehension (SC) task that included isolated words and sentences that make sense, in addition to undergoing reading and EF behavioral assessment. Functional connectivity within and between four EF networks related to top-down and bottom-up processing were calculated. ResultsChildren with dyslexia scored significantly lower in reading and EF testing in several subdomains compared to TR. Children with dyslexia displayed decreased accuracy in both task conditions compared to TR during the SC task. Neuroimaging data analysis revealed that TR had greater functional connectivity within and between top-down and bottom-up processes, in the sentence vs. isolated word condition, compared to children with dyslexia. Discussion: TR demonstrate a reliance on top-down and bottom-up networks only during sentence comprehension. In children with dyslexia, however, this reliance was not found in either of the task conditions, suggesting that both conditions were equally challenging for them. These findings emphasize the involvement of EF networks in the reading comprehension process and highlight their impaired functionality among children with reading difficulties.