Poster Session D, Monday, March 25, 8:00 – 10:00 am, Pacific Concourse
Assessing the relationship between reading ability and dyslexia: A Behavioral and fMRI study
Stephen Gonzalez1,2, Rita Barakat2,3, Maya Rajan2,4, Kristi Clark1,2,3; 1University of Southern California Neuroimaging and Informatics Masters Program, 2Connectivity and Network Development Laboratory (CANDL) Groups, Laboratory of Neuro Imaging and USC Mark and Mary Stevens Neuro Imaging and Informatics Institute, 3University of Southern California Neuroscience Graduate Program, 4University of Southern California Psychology Program
Dyslexia is traditionally thought to be a product of a deficit in phonological processing. Other theories suggest a deficit in integration of phonological and orthographical processing streams. It has also been shown that areas participating in these processes show hypoactivity during phonological tasks, and that this pattern of activation is more strongly related to dyslexia as opposed to reading ability. Using functional magnetic resonance imaging, we examined key regions of the left hemisphere reading network that contribute to orthographic and phonological processing, as well as primary convergence points of these two streams, while including reading ability in our regression model. Participants were between ages 8-12, right-handed, and were monolingual English speakers. We presented subjects with phonological and orthographical decision tasks which adapted to their performance over the course of each task. For each task, we assessed subject’s performance by measuring the average difficulty level across all trials, as well as the frequency subjects switched difficulty level within a task (variability). Reading ability was measured using the Woodcock-Johnson Test of Achievement (WJ-III). Behavioral analysis revealed dyslexic subjects exhibited lower mean difficulty level, and higher variability on each task when compared to controls. Preliminary functional analysis for the phonological task highlighted differences in activation between groups in the superior temporal gyrus, a location shown to contribute to phonemic processing. These findings suggest a difference in phonological processing between dyslexic individuals and non-deficient controls. Further analysis is needed to determine the magnitude of these differences and if they are replicable across subject populations.
Topic Area: METHODS: Neuroimaging