Examining Brain Connectivity and Reading Ability in Children

In this thesis, I investigated the relationship between functional and structural connectivity and reading ability in children. Prior research has tended to use single word reading measures or composite measures, however this is problematic as reading is a complex skill relying on multiple subskills, such as decoding efficiency, sight word reading efficiency, reading comprehension, and rapid automatized naming. As a result, the multi-faceted relationship between brain connectivity and reading ability is not well understood. I aimed to address this issue by considering multiple reading subskills while examining the neural substrates of reading. In Chapter 2, I examined how individual differences in decoding efficiency, sight word reading efficiency, reading comprehension, and rapid automatized naming relate to resting-state functional connectivity from regions of the brain’s reading network. I found that distinct functional networks in both hemispheres of the brain support different components of reading in children. In Chapter 3, I built on these findings to examine how individual differences in the same reading subskills are associated with structural connectivity in reading-related white matter tracts, as measured by diffusion tensor imaging. Similar to Chapter 2, the results of Chapter 3 suggested that different components of reading ability are supported by structural characteristics in distinct bilateral tracts of the brain. Importantly, many of the effects observed in Chapters 2 and 3 were found to be specific to reading subskills and were not associated with more general cognitive abilities. In Chapter 4, I examined how improvements in reading ability are related to changes in structural and functional connectivity, by measuring brain connectivity pre- and post-intervention in a group of children with reading disability. I also investigated whether individual differences in the amount of improvement in reading ability post-intervention was predicted by pre-intervention brain connectivity. I found that gains in reading ability were associated with changes in resting-state functional connectivity, particularly between reading-related regions and frontal regions as well as regions of the default mode network. Changes in white matter microstructure of the right arcuate fasciculus were strongly associated with gains in single word reading abilities. Additionally, results showed that distinct pre-intervention characteristics of resting-state functional connectivity and white matter integrity predicted the magnitude of subsequent gains in reading ability following the reading intervention. Chapter 5 summarizes the findings of this thesis in relation to the current literature and presents recommendations for future research on reading ability and brain connectivity