Poster A86, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall
Bilingual dyslexic children show language-universal deficits in the brain
Qing Zhang1, Xiaohui Yan1, Fan Cao1;1Department of Psychology, Sun Yat-Sen University
Previous study has shown that Chinese-speaking children also show phonological deficits behaviorally and neurologically (Cao et al., 2016). If the underlying cause for DD is language-universal, bilingual speakers with DD could shed light on the neural basis of DD across languages. The existing results of the neural signature of bilingual (Chinese and English) DD is not consistent (Siok et al., 2008, Hu et al., 2010; You et al., 2010), mainly because none of them has examined both L1 and L2 simultaneously. To this end, we collected data from bilingual dyslexic children, and directly compared their deficits in both languages. Seventy-six Chinese children were recruited, with 20 children with DD in both Chinese and English, 17 age-matched controls for the Chinese task (AC), 21 reading-matched controls for the Chinese task (RC), and 18 age-matched controls for the English task (EC). A visual rhyming judgment task was adopted in the fMRI, in which two words were presented sequentially in the visual modality, and participants were asked to determine whether they rhyme or not. In a full factorial ANOVA of 2 groups (dyslexia, control) by 2 languages (Chinese, English), we found a main effect of group at two clusters in the left IFG, the left precuneus, and the left ITG, with greater activation in AC and EC than in DD. At the ROI level, we compared RC and DD, and found that RC was similar to AC and greater than DD at the left precuneus and left ITG (t(1,35)=2.84, p=0.008 for the precuneus; t(1,35)=2.50, p=0.017 for the ITG). It suggests that these two deficits are associated with dyslexia core deficits, since RC showed the same pattern as AC. At the two clusters in the left IFG, however, RC did not show significant difference than DD, suggesting these deficits might be accumulated with the experience of being DD. No interaction was found. These deficits at the left IFG overlaps with the language core areas from another study by Liu et al. (in progress) which proposed a language core network associated with the abstract and symbolic nature of language. The overlaps lie on the left IFG and the middle part of the precentral gyrus, very close to the location of laryngeal motor cortex (LMC) (Simonyan, 2013), suggesting that speech production deficit might play a more important role in phonological deficit experienced by children with DD. Correlation analysis also found different patterns for the dyslexia core areas and dyslexia accumulated areas. Within children with DD, we found negative correlation between accuracy on the task and activation in the left precuneus, and positive correlation between reading skill and activation in the left IFG. It suggests that children with more severe DD showed greater activation in the left precuneus and less activation in the left IFG. We hypothesize that the core deficits at the left precuneus and ITG are associated with the origin of DD, which then interferes with the development of the IFG.
Themes: Reading, Multilingualism
Method: Functional Imaging