Neural Mechanisms Underlying Literacy in Bilingual Children with Typical and Atypical Reading Development

One in five children in the United States is bilingual. Despite a plethora of research on monolingual reading development, it is unclear how the brain develops to support literacy when two languages are being learned. Furthermore, it is poorly understood how these neural processes develop in bilingual children who are at risk of having reading difficulties. This study aimed to identify the neural correlates of literacy in 69 bilingual middle schoolers with English reading skills above and below state of Texas benchmarks. Children were given a language questionnaire, proficiency assessments, and were asked to complete reading-related tasks while in a magnetic resonance imaging (MRI) scanner that collected functional brain data. Some evidence was found for Hypothesis 1, which was that better task performance would predict ventral reading route activation and worse performance would predict dorsal activation. Specifically, whole-brain general linear modelling showed a positive relationship between task performance and left occipitotemporal activity (part of the ventral route). On the other hand, there was an inverse relationship between task performance and two non-hypothesized areas (right angular gyrus and secondary visual area). These findings indicate that, for bilingual children, recruitment of right hemisphere regions may help compensate when orthographic processing in the second language is less (or not yet) automatized. Hypothesis 2, which was that English proficiency would mediate the relationship between task performance and task activation, was rejected. Instead, post hoc analyses showed that self-report, but not objective, proficiency predicted brain activation in motor and visual regions. These findings highlight the notion that self-report proficiency can capture certain components of language skill that objective measures do not.