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Poster A24, Wednesday, November 8, 10:30 – 11:45 am, Harborview and Loch Raven Ballrooms

Is the Middle Frontal Gyrus Implicated in Reading?

Maria Stacy1, Sarah Dyer1, Michelle Kibby1;1Southern Illinois University-Carbondale

Objective: Despite recent growth in our understanding of the neurobiological basis of reading, much of this research has focused upon single-word reading, while higher-level reading skills, like reading comprehension, have received less attention. Hence, this study investigated the relationship between middle frontal gyrus volume (MFG) and basic reading skills, like single word reading and reading fluency, and more complex reading skills, like reading comprehension, to ascertain whether volume in this region is equally related to differing aspects of reading ability. This study focused on MFG volume because previous research has indicated that this region is involved in working memory (Narayanan, et al, 2005; Tor & Edward, 2003), and that working memory contributes to both single word reading (decoding) (Messer, Henry & Nash, 2016) and reading comprehension (Cain, Oakhill & Bryant, 2004; Tighe & Schatschneider, 2014). Method: Data were collected as part of larger, NIH funded studies on a community sample (R03 HD048752, R15 HD065627). Children, ages 8 to 12 years, with reading disability (n=19), ADHD (n=42), both disorders (n=20), or typically developing controls (n=28) were administered subtests from the Woodcock-Johnson III including Passage Comprehension (PC), Reading Fluency (RF) and Letter-Word Identification (LWI). In addition, all participants completed a T1 weighted MRI scan using a 1.5T Phillips Intera scanner. Results: Two hierarchical multiple regressions were performed to statistically predict left, then right, middle frontal gyrus volume (MFG), with the three reading measures as predictors. The regression predicting left MFG volume was significant: adjusted R2=.06, F(3, 102) = 3.21, p = .03. In addition, the regression predicting right MFG volume was significant: adjusted R2= .08, F(3, 102) = 3.92, p = .01. Passage Comprehension was a significant predictor for both left (β = .22, p = .03) and right (β = .32, p = .001) hemispheres, but Letter Word Identification and Reading Fluency were not (ps > .10). Conclusion: Reading comprehension ability predicted bilateral middle frontal gyrus volumes. In contrast, word recognition and reading fluency did not significantly predict either left or right middle frontal gyrus volume. It is logical that a reading comprehension task, which requires more working memory than single word reading, would be a better predictor of middle frontal gyrus volume than basic reading, as the MFG is implicated in cognitive executive functioning, including working memory. However, it is surprising that PC better predicted right hemisphere volume than left hemisphere volume. Traditionally, the left hemisphere has been more closely associated with verbal processing than the right. However, researchers have reported that the kind of working memory task being completed by each hemisphere may affect which hemisphere is more involved. Tsukiura, et al (2001) asserted that while the left hemisphere is more involved in maintenance of information, the right hemisphere is more involved in manipulation of information held in mind. Updating and synthesizing of information is required when comprehending written text, and it may be these aspects of reading that are reflected in the relationship with right MFG volume.

Topic Area: Language Disorders

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