Poster A83, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall
Localizing activation of component processes of reading in adult struggling readers
Rachael Harrington1,2, C. Nikki Arrington1, Lisa C. Krishnamurthy1,2, Venkatagiri Krishnamurthy2,3, Bruce Crosson1,2,3, Robin Morris1;1Georgia State University, 2Center for Visual and Neurocognitive Rehabilitation, Department of Veterans Affairs, 3Emory University School of Medicine
Reading is an essential skill necessary for many activities of daily living. Dyslexia most commonly occurs neurodevelopmentally and persists into adulthood in adult struggling readers (SR). Adult SR typically have poor fluency, receptive vocabulary and reading comprehension, along with poor phonological skills when compared to age-matched and reading age-matched controls. This represents the cumulative result of early phonological reading deficits (Greenberg et al., 1997, 2002, 2011). Functional imaging of children with developmental dyslexia shows decreased activation in the left-hemisphere visual system and dorsal stream with increased activation of right hemisphere visual and language systems (Shaywitz & Shaywitz, 2005). This project aims to understand the altered or compensatory neural networks underlying adult SR. Eleven adult SR and 11 age-matched controls were given a battery of reading tests and the Fast fMRI localizer task, a covert reading task that is highly effective at identifying brain regions that are sensitive to orthographic, phonological or semantic properties of words. Scans were performed on a Siemens 3T Trio (TR = 2 sec, TE = 30 ms, 3x3x4 mm). We performed standard image preprocessing and processing with in-house pipelines. Trial types were regressed to obtain contrast images and we applied continuous brain/behavior correlation analysis between subject reading skill and activation within specified ROIs. Following t-tests (p<0.05, cluster size =50) for adult SR relative to controls, we found increased activity in right inferior parietal lobe (r-IPL) during reading of phonologically related word sets and in right inferior frontal gyrus (r-IFG) and right middle temporal gyrus (r-MTG) during reading of semantically related word sets. Within the control group, we found positive correlations with left fusiform gyrus (l-FG) during reading of semantically related words sets and Woodcock Johnson 3: Reading Fluency subtest scores (WJ3RF) (r=0.607, p=0.048). We also found positive correlations when reading phonologically related words between l-IPL activation and the WJ3: Letter Word ID subtest (WJ3LWID) (r =0.828, p=0.002). Within the SR adult group, we found positive correlations between the WJ3RF and beta-weights during reading of semantically related words in regions similar to those of the control group, such as l-IPL (r=0.661, p=0.027) and l-FG (r=0.858, p=0.001), but also in right hemisphere regions like r-IPL (r=0.652, p=0.03), right inferior frontal gyrus (r-IFG) (r=0.694, p=0.018), and r-FG (r=0.869, p=0.001). Positive correlations also were present between RJ3LWID and reading of phonologically related word sets again in l-IPL (r=0.88, p=0.001) and l-FG (r=0.75, p=0.008) but also in right hemisphere regions such as r-IPL (r=0.79 p=0.004) and r-FG (r=0.71, p=0.013). While the increased right hemisphere activation as compared to controls is consistent with previous literature from children with dyslexia, we also found that right hemisphere activation is correlating positively with behavioral testing in adult SR. These results need to be explored in a larger group and further analysis is needed to determine if this activation is adaptive or maladaptive for reading. A better understanding of the neurobiology of reading can help inform treatment of both adult SR and other non-developmental reading disorders in adults.
Themes: Reading, Disorders: Developmental
Method: Functional Imaging