The goal of this project is to develop and test age appropriate lexical tasks to differentiate between children who are normally developing and children with communication disorders (poor readers and phonological dyslexics). Poor readers tend to have a history of language problems in semantic processing coupled with deficits in decoding between orthography and phonology, whereas phonological dyslexics have a specific deficit in decoding. We wish to differentiate between these groups in patterns of brain activation during functional magnetic resonance imaging (fMRI). We propose a chronological age match (12-year-olds) and a reading level match (9-year-old normally developing children matched to older children with communication disorders) experimental design so that we can examine issues of developmental delay versus deficit. We expect that we will able to differentiate between these groups in specific aspects of lexical processing, so our functional activation tasks are designed to examine intra-modal processing (auditory rhyming and visual spelling tasks), cross-modal processing (auditory spelling and visual rhyming tasks) and amodal word comprehension (auditory and visual meaning tasks). We expect that both the phonological dyslexics and poor readers will show abnormalities during the spelling and rhyming tasks in the two modalities, whereas we expect that only the poor readers will show abnormalities during the auditory semantic task. In order to be able to more clearly attribute group differences to lexical processing, we wilt use multiple baselines (simple versus complex) and a parametric difficulty manipulation (orthographic/phonologic consistency in word pairs for spelling and rhyming tasks and association strength for the semantic tasks). This project will provide tasks, an experimental approach, and a method for evaluating differences between groups with communication disorders that could potentially be used as a diagnostic and intervention tool.
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