Atypical Relationships Between Neurofunctional Features of Print-Sound Integration and Reading Abilities in Chinese Children With Dyslexia

Abstract

Conquering print-sound mappings (e.g., grapheme-phoneme correspondence rules) is vital for developing fluent reading skills. In neuroimaging research, this ability can be indexed by activation differences between audiovisual congruent against incongruent conditions in brain areas such as the left superior temporal cortex. In line with it, individuals with dyslexia have difficulty in tasks requiring print-sound processing, accompanied by a reduced neural integration. 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. In this study, we applied a passive audiovisual integration paradigm with functional magnetic resonance imaging to investigate the possible dysfunctions in processing character-sound (opaque; semantics can be automatically accessed) and pinyin-sound associations (transparent; no particular meaning can be confirmed) in Chinese dyslexic children. Unexpectedly, the dyslexic group did not show reduced neural integration compared with typically developing readers in either character or pinyin experiment. However, the results revealed atypical correlations between neural integration and different reading abilities in dyslexia. Specifically, while the neural integration in the left inferior frontal cortex in processing character-sound pairs correlated with silent reading comprehension in both children with and without dyslexia, it was associated with morphological awareness (semantic-related) in controls but with rapid naming (phonological-related) in dyslexics. This result indicates Chinese dyslexic children may not use the same grapho-semantic processing strategy as their typical peers do. As for pinyin-sound processing, while a stronger neural integration in the direction of "congruent > incongruent" in the left occipito-temporal cortex and bilateral superior temporal cortices was associated with better oral reading fluency in the control group, an opposite pattern was found in dyslexia. This finding may reflect dyslexia's dysfunctional recruitment of the regions in grapho-phonological processing, which further impedes character learning.

Keywords: Chinese; audiovisual integration; character; dyslexia; individual differences; pinyin.

Figure 1

Schematic description of the fMRI experimental procedure (A–C) for a run, a block, and a mini-block, respectively] and stimuli examples (D). Aud, auditory; avC, audiovisual congruent; avI, audiovisual incongruent; Fix, fixation; Vis, visual. *Was the visual target of the fMRI task, without any meaning.

Figure 2

(A) Results of the voxel-wise whole-brain ANOVA on the character conditions. Only clusters showing a significant main effect of condition were identified at the FWE corrected threshold of p-cluster < 0.05 (p-voxel < 0.001 for height). No region showed significant main effect of group or group × condition interaction. (B) The bar plots present brain activation in the audiovisual congruent and incongruent conditions for the control and dyslexic groups. (C) The scatterplots display correlations between the neural audiovisual integration effect (avC-avI) in the left IFC with silent reading comprehension proficiency and related cognitive-linguistic skills (morphological awareness, rapid naming). avC, audiovisual congruent; avI, audiovisual incongruent; IFC, inferior frontal cortex; STC, superior temporal cortex. ***p < 0.001, *p < 0.05, ^†p < 0.1.

Figure 3

(A) Brain map of regions showing significant between-group differences in the correlation between the audiovisual integration effect and oral reading fluency (FWE corrected p-cluster < 0.05, p-voxel < 0.001 for height). The scatterplots presents correlations in each group (blue: control; red: dyslexic) in the left OTC (B), STC (C), and right STC (D). avC, audiovisual congruent; avI, audiovisual incongruent; OTC, occipito-temporal cortex; STC, superior temporal cortex. ***p < 0.001, **p < 0.01, *p < 0.05.