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Neural correlates of semantic processing in Chinese children with dyslexia
Poster Session C, Thursday, October 1, 10:45 am - 12:45 pm, Wangari Maathai
Li-Ying Fan1, Yueh-Lin Li2, Hsin-Chin Chen3, Shiou-Yuan Chen4, Tai-Li Chou2; 1National Taipei University of Education, 2National Taiwan University, 3National Chung Cheng University, 4University of Taipei
Reading is a complex process typically involves multiple levels of language processing, including orthographic, phonological and semantic (Cao et al., 2009; Catts et al., 2001; Cone et al., 2008; Jasinska and Petitto, 2014). Dyslexia, a heritable neurodevelopmental disorder, refers to a specific learning difficulty with word recognition, decoding, and spelling. Little is known about the neural mechanisms underlying atypical semantic processing in young children. The aim of the present study was to use functional Near Infrared Spectroscopy (fNIRS) to investigate whether brain activation of semantic processing would differ in children with dyslexia relative to typically developing (TD) children. Sixteen children with dyslexia (mean age, 8.3 ± 0.9; age range 7.1-10.1; mean Chinese character recognition percentile = 19.68), and 16 gender- and age-matched TD children (mean age, 8.3 ± 0.9; age range 7.3-10.1; mean Chinese character recognition percentile = 73.94) were recruited based on the Chinese character recognition test. Participants completed a battery of literacy tasks measuring vocabulary, phonological awareness, morphological awareness, and reading ability. During the fNIRS imaging task, children heard two words and were asked to indicate if word pairs were related in meaning. The semantic judgment task included two levels of semantic difficulty requiring either high-association (easy) or low-association (difficult). The contrast of the high- versus low-association was defined to reveal the hemodynamic activity associated with semantic processing. We investigated the differences in behavioral performance and neural activity between children with dyslexia and TD children. Also, we performed Pearson’s correlations between brain activity assessed by beta values of significant brain regions and the scores of literacy tasks. Behavioral results indicated that TD children were more accurate than children with dyslexia in the high-association condition. In addition, fNIRS results revealed that TD children exhibited stronger activation in the right middle frontal gyrus (MFG) than children with dyslexia during the high- versus low-association contrast. Furthermore, increased activation in the right MFG was positively correlated with morphological awareness scores. Overall, our findings suggest that TD children might have a better elaborated semantic system, facilitating greater right MFG activation for semantic feature selection in the high- versus low-association contrast compared to children with dyslexia.
Topic Areas: Disorders: Developmental, Meaning: Lexical Semantics