On the Relations among Linguistic Subsystems in Typically Developing Children and Children with Neurodevelopmental Disorders

Language is a complex multifaceted system, and as we use spoken and written language we simultaneously recruit an array of interrelated linguistic subsystems. While these subsystems have been studied extensively during language acquisition, we know little about the organization and relations among these components in the school-age years. In the four investigations of this dissertation, I use classically defined components of language (phonological, lexico-semantic, and syntactic) as well as components of reading (orthographic and semantic) as a tool to explore the relations amongst elements that comprise the language system in school aged typically developing children (TD) and children with neurodevelopmental disorders (aged 7- 12). Investigating the composition of the language system in children with neurodevelopmental disorders that affect language will not only help to create more targeted interventions for these children, but will also provide a unique window through which to better understand the underlying structure and organization of language in TD children. Chapter 1 investigates the development of and relation between orthographic (a visuospatial-based skill) and semantic (a language-based skill) components of single word reading in typically developing children in the first through fourth grade. Chapter 2 explores these processes in High Functioning children with Autism (HFA) and children with Williams syndrome (WS); children with HFA and WS show opposite strengths and weaknesses in visuospatial and language cognitive domains, and neither population develops reading typically. Chapter 3 extends these results to include spoken and written language at increasing levels of linguistic complexity, and explores how these components relate to one another in HFA and TD, and how they are related to the ability to organize and produce a spoken personal narrative. Chapter 4 considers the underlying neural correlates of linguistic components in a case study format with two children with unilateral Perinatal stroke (one right, one left hemisphere) using multimodal structural imaging techniques alongside a detailed analysis of language performance. Together, results from these investigations suggest that assessing the associations among linguistic subsystems provides valuable information, which will add to our understanding of the mechanisms underlying language impairment in children with neurodevelopmental disorder