The proposed work seeks to develop a better understanding of the developmental time course of language processing, specifically orthographic and phonological word processing during silent reading. The end goal of this project is to further elucidate neural correlates of reading deficits in dyslexia. Because dyslexia has been linked to phonological processing deficits, masked priming will be used to examine the automatic mechanisms involved in orthographic and phonological processing. The mechanism underlying this deficit in reading can be occurring at several different stages of processing (e.g., mapping of orthographic information to phonology, activating an appropriate phonological representation). Using masked priming and brain measures (event-related potentials (ERPs) and fMRI) will allow us to determine more precisely which of these mechanisms is disrupted in dyslexia and intact in skilled readers. Prior fMRI research has established that during phonological processing parietotemporal and frontal regions are important, while ERP studies have outlined the timing of phonological processing in the brain. In terms of orthographic processing, the visual word form area (VWFA) has been suggested to subserve language processing through its role in visual word perception and again ERPs have established a series of effects sensitive to word form processing during orthographic priming. Using fMRI and ERPs we will establish the developmental time course of when and where in the brain these processes occur and how they are disrupted in dyslexia. By using behavioral, electrophysiological and neuroimaging methodologies, the relationship of these brain areas in visual word perception and the subsequent mapping of these lower level features (word form;sound) onto higher level semantic meaning necessary for successful reading, can be established. Specifically, this project will take place in three stages: the first stage will consist of an fMRI and ERP experiment with a normal college-age population studying repetition priming effects with words manipulating the phonology and orthography between word pairs. The second stage of this project will extend this research to a group of normally developing children (8-10 years old) using again fMRI and ERPs and the final stage of the project will extend this paradigm to a population of children with dyslexia (8-10 years old). The relevance of this proposal to public health is being able to better determine the underlying mechanisms involved in deficits in reading. This research will be relevant for establishing patterns of brain activity associated with normal and impaired reading, which may lead to being able to predict reading difficulties or a predisposition for these difficulties
| Eddy, Marianna D; Grainger, Jonathan; Holcomb, Phillip J et al. (2016) Orthographic and phonological processing in developing readers revealed by ERPs. Psychophysiology 53:1776-1783 |
| Eddy, Marianna D; Grainger, Jonathan; Holcomb, Phillip J et al. (2014) Masked priming and ERPs dissociate maturation of orthographic and semantic components of visual word recognition in children. Psychophysiology 51:136-41 |
| Blackburne, Liwei King; Eddy, Marianna D; Kalra, Priya et al. (2014) Neural correlates of letter reversal in children and adults. PLoS One 9:e98386 |
