An audiovisual integration deficit underlies reading failure in nontransparent writing systems: An fMRI study of Chinese children with dyslexia

Establishing the associations between speech sounds and visual scripts is an essential step for reading acquisition. Audiovisual integration deficits have been proposed to be a cause of developmental dyslexia, and this has been evidenced by behavioral and neural findings from alphabetic languages with relatively transparent orthographies. Here, using functional magnetic resonance imaging (fMRI) in a lexical decision task, this study examined the neural correlates of audiovisual integration deficits in Chinese children with dyslexia and age-matched controls. The results indicated that the children with dyslexia showed a reduced audiovisual congruency effect in the left angular gyrus, left superior temporal gyrus and left middle and superior frontal gyrus. Moreover, dyslexics showed reduced functional connectivity for the congruency effect between the left angular gyrus and both the left lingual gyrus and left cerebellum. The regional activation and functional connectivity abnormalities might underlie the ill-developed correspondence between orthographic and phonological information in Chinese dyslexia. This study, for the first time, illustrates the neural mechanisms of the audiovisual integration deficit in dyslexia in a nontransparent logographic writing system, extending our understanding of the neural basis of dyslexia.