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Poster D69, Thursday, November 9, 6:15 – 7:30 pm, Harborview and Loch Raven Ballrooms

Using phonemic, rapid naming and orthographic measures to predict volume of the posterior cingulate

Hannah Travis1, Jennifer Schlak1, Ruchi Brahmachari1, Andrew Molnar1, George Hynd2, Michelle Kibby1;1Southern Illinois University-Carbondale, 2Oakland University

Introduction: The cingulate gyrus is not as commonly associated with dyslexia as other brain structures, but neurobiological evidence has shown that the posterior cingulate is an important region for reading (Graves et al., 2010; Hosseini et al., 2013). However, there may be differences in which hemisphere is more dominant, and for which skill, of reading. Thus, we examined the relationship of bilateral posterior cingulate volume with component skills for reading. We hypothesized that left hemisphere volume would be correlated with phonological processing/short-term memory, rapid automatic naming and orthographic processing, showing a differential hemispheric relationship. Methods: Participants included 42 children between the ages of 8-12 years who had reading disability, ADHD, both disorders or were typically developing. The sample was predominantly Caucasian (84%) and male (67 %). Data was collected as part of a larger study focused on dyslexia (NIH/NICHD R01 HD26890). Brain tracing was supported through a separate grant (NIH/NICHD R03 HD048752). Phonological repetition/short-term memory was measured with Nonword Repetition (NWR), and rapid naming was measured with Rapid Letter Naming (RLN), both from the CTOPP. Orthographic processing (OP) was measured with a composite score based off two experimental measures: correct spelling and homophone identification. The Vocabulary subtest from the Weschler Abbreviated Scale of Intelligence (WASI) was used as a covariate to control for verbal intelligence. A 1.5T GE Sigma scanner was used to obtain a 3-D, T1 weighted image. In terms of measurement, first, the cingulate was traced on every slice in the sagittal plane using guidelines from Crespo-Facorro et al. (1999). Next, the cingulate was divided into three regions, and the posterior region ran from the central sulcus to its posterior conclusion. Inter-rater reliability was > 0.90. Results: For both analyses, multiple hierarchal regression was used to examine the relationship between the orthographic processing composite, Nonword Repetition and Rapid Letter Naming (Block 2) and posterior cingulate volume (for both the left and right hemispheres), controlling for Vocabulary (Block 1). We found that RLN predicted left posterior cingulate volume (Delta R^2 =.234, p=.018; Beta=.568, p=.006). We also found that Nonword Repetition (Beta=.527, p=.001) and the orthographic composite (Beta=-.597, p<.001) predicted right hemispheric volume (Delta R^2=.456, p<.001). Conclusion: RLN was the only significant predictor of left posterior cingulate volume, while NWR and OP were significant predictors of right volume. Previous evidence supports a relationship between phonological processing and the posterior cingulate (Bolger et al., 2008). The relationship between right volume and these measures may be due to the visual component in orthography (Mesman and Kibby, 2011) and use of visualization in the STM task. It also could be due to the nature of our sample, as approximately half of our participants had some form of reading disability. There is evidence to suggest that increased activation in the right posterior hemisphere is related to worse spelling abilities (Gebauer et al., 2012), so it is possible that the children with RD are compensating for left dysfunction by relying on their right hemisphere more.

Topic Area: Phonology and Phonological Working Memory

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