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Poster E48, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Performance differences on reading skill measures are related to differences in cortical grey matter structure in young adults

Clinton Johns1, Andrew A. Jahn1, Hannah R. Jones2, Dave Kush1,3, Peter J. Molfese1,4, Julie A. Van Dyke1, James S. Magnuson1,5, Whitney Tabor1,5, W. Einar Mencl1, Donald P. Shankweiler1,5, David Braze1;1Haskins Laboratories, 2University of Rochester, 3Norwegian University of Science and Technology, 4National Institutes of Health, 5University of Connecticut

Individual differences in reading comprehension and its components often correlate with differences in functional activity in task-relevant brain regions (e.g., Clements-Stephens et al., 2012; Meyler et al., 2008). There is also some evidence that such individual differences correlate with differences in neuroanatomical structure (for review Richardson & Price, 2009). However, most evidence to date derives from contrasts between clinical (e.g., dyslexic) and non-clinical groups. Non-clinical studies of individual differences in cortical structure and cognitive ability have typically utilized small or homogeneous samples (e.g., college students). Further, such studies typically assess only a narrow range of language-related cognitive abilities and skills, such as decoding ability (Jednoróg et al., 2015), print exposure (Goldman & Manis, 2013), vocabulary knowledge (Lee et al., 2007; Richardson et al., 2010), or overall reading comprehension ability (Welcome et al., 2011). Thus, interpreting the largely heterogeneous findings of such studies presents a challenge. Therefore, we conducted an investigation of potential relations between cortical grey matter structure and individual differences on a broad battery of literacy-related skill assessments in a community-based sample of young adults with a wide range of linguistic ability. We recruited 35 right-handed native English speakers (ages 16-24 years, 17 female) from the local New Haven area. Each participant completed two experimental sessions – one scanning session, and one behavioral testing session – on separate days. During behavioral testing, participants completed a test battery, including decoding, phonological awareness, rapid naming, both oral and print comprehension, reading fluency, print exposure, working memory capacity, and reasoning ability. During the scanning session, we acquired whole-head, high resolution T1-weighted anatomical images. Subsequent analyses in Freesurfer calculated cortical grey matter volume (GMV) and thickness (GMT) for brain parcellations based on the Desikan-Killiany atlas. Whole-brain analysis revealed that individual differences on multiple battery measures were associated with differences in cortical structure. Of primary interest, decoding ability was positively correlated with GMV in left superior temporal sulcus (STS), and grey matter thickness GMT in right superior temporal gyrus (STG). Print exposure was negatively correlated with GMT of pars opercularis in left inferior frontal gyrus (IFG) and the left fusiform gyrus (including the visual word form area, VWFA). Both measures were also related to supramarginal gyrus (SMG), but with differential specificity: decoding was positively associated with GMV in left anterior SMG (aSMG), and print exposure was negatively associated with GMT in left posterior SMG (pSMG). These results are broadly consistent with previous functional findings that have associated aSMG, left IFG, left STS, and VFWA with establishing relations between different types of lexical (e.g., phonological, orthographic) information (e.g., Shankweiler et al., 2008). In addition, they confirm previous findings (Lee et al., 2007; Richardson et al., 2010) suggesting a structural role for pSMG with no functional analog: as a site related to the assembly of high-dimensional lexical representations via the binding of orthographic, phonological, and semantic information. Finally, our results suggest that while aSMG may be chiefly concerned with phonological aspects of grapheme-to-phoneme translation, pSMG may be primarily related to with orthographic aspects of this process.

Topic Area: Methods

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