Atypical relationships between neurofunctional features of print-sound integration and reading abilities in Chinese children with dyslexia

Conquering grapheme-phoneme correspondence is necessary for developing fluent reading in alphabetic orthographies. In neuroimaging research, this ability is associated with brain activation differences between the audiovisual congruent against incongruent conditions, especially in the left superior temporal cortex. Studies have also shown such a neural audiovisual integration effect is reduced in individuals with dyslexia. However, existing evidence is almost restricted to alphabetic languages. Whether and how multisensory processing of print and sound is impaired in Chinese dyslexia remains underexplored. Of note, semantic information is deeply involved in Chinese character processing. In this study, we applied a functional magnetic resonance imaging audiovisual integration paradigm to investigate the possible dysfunctions in processing character-sound pairs and pinyin-sound pairs in Chinese dyslexic children compared with typically developing readers. Unexpectedly, no region displayed significant group difference in the audiovisual integration effect in either the character or pinyin experiment. However, the results revealed atypical correlations between neurofunctional features accompanying audiovisual integration with reading abilities in Chinese children with dyslexia. Specifically, while the audiovisual integration effect in the left inferior cortex in processing character-sound pairs correlated with silent reading comprehension proficiency in both dyslexia and control group, it was associated with morphological awareness in the control group but with rapid naming in dyslexics. As for pinyin-sound associations processing, while the stronger activation in the congruent than incongruent conditions in the left occipito-temporal cortex and bilateral superior temporal cortices was associated with better oral word reading in the control group, an opposite pattern was found in children with dyslexia. On the one hand, this pattern suggests Chinese dyslexic children have yet to develop an efficient grapho-semantic processing system as typically developing children do. On the other hand, it indicates dysfunctional recruitment of the regions that process pinyin-sound pairs in dyslexia, which may impede character learning.