Poster E58, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Brain mechanisms underlying visuo-orthographic deficits in children with developmental dyslexia
Gregory Spray1, Xin Yan1, Yanni Liu2, Fan Cao1; 1Michigan State University, 2University of Michigan
The phonological deficit hypothesis has been the core hypothesis of developmental dyslexia (DD); however, reading is a complex process and orthographic skills play an important role in reading. Previous studies have suggested an orthographic deficit in children with DD; however, little is known whether the orthographic deficit is independent of visual skill. The current study examined the brain mechanisms of visuo-orthographic deficit in 23 Chinese children with DD in comparison to 19 age-matched controls (AC) and 15 reading-matched controls (RC) using functional magnetic resonance imaging (fMRI) under perceptual and lexical tasks. We found that AC and RC had greater activation than DD in the left precuneus for both the lexical and the perceptual tasks. It suggests a common brain mechanism of visual and orthographic deficit, which may be associated with visual spatial processing. Psychophysiological interactions (PPI) analysis revealed that the connectivity from the LMOG to the left IFG was greater in controls than DD for only the lexical task, whereas the connectivity from the LMOG to the bilateral cuneus was greater in controls than DD for only the perceptual task. It suggests differentiated brain mechanisms for orthographic and visual deficits in DD. In contrast, the group differences in the connectivity with the RMOG did not show task differentiation, suggesting that the RMOG is involved in both tasks in a similar manner. Our findings provide strong evidence for deficits in basic visual spatial processing in DD and some specific deficits in processing orthography in comparison to processing visual symbols.
Topic Area: LANGUAGE: Development & aging