Investigating the neural circuitry of spelling in reading impairments: A functional connectivity approach

Abstract

Background. Writing skills are imperative to successful academic and social functioning in todayâs literate society. Yet, literature exploring the underlying mechanisms associated with written communication, namely spelling, is surprisingly limited. This study looked into the neuropsychological profile for spelling in skilled and impaired individuals. Methods. 19 skilled individuals and 8 individuals with reading impairments performed behavioural and fMRI tasks. Behavioural measures included reading and spelling tasks and three measures to assess their phonological, orthographic and morphological awareness. In fMRI, they completed three conditions of an in-scanner spelling task called letter probe task (LPT). LPT involved deciding if a visually presented letter is in the spelling of an auditorily presented word (e.g., decide if letter âfâ is in the word âphaseâ?). The three conditions of LPT were as follows: 1) retrieval of the whole word spelling representations was required (e.g., âcâ in yacht), 2) retrieval of the whole word spelling representation was optional (e.g., ârâ in charm), and 3) non-words or made-up words needed to be generated (e.g., âbâ in bint). Functional connectivity patterns were analyzed between twelve left-hemispheric brain regions that have been implicated in reading and spelling literature. Results. We found that reading impaired individuals had low levels of phonological and morphological awareness and they used their language awareness skills differently than skilled readers. Functional connectivity results demonstrated a lack of functional connectivity from regions associated with orthographic (fusiform gyrus), phonological (superior temporal gyrus) and articulatory (putamen) processing. Implications. Results from the study will increase the current state of knowledge regarding the underlying neurobiology of spelling performance and add to the literature on acquisition, refinement and maintenance of written communication skills.