Slide Slam D13
Distinct relationships between neural correlates of print-sound integration and reading abilities in Chinese children with and without dyslexia
Zhichao Xia1, Ting Yang1, Xin Cui1,2, Fumiko Hoeft2,3,4,5, Hong Liu1,3, Xiangping Liu1, Hua Shu1; 1Beijing Normal University, 2Haskins Laboratories, 3University of Connecticut, 4University of California, San Francisco, 5Keio University School of Medicine
Effortless print-sound integration is a hallmark of fluent reading and is crucial for typical reading acquisition. The underlying brain network consists of the left superior temporal cortex (STC) as the central node and other cortical areas such as the left occipito-temporal cortex (OTC) and inferior frontal gyrus (IFG) playing specific roles. Adopting the audiovisual paradigm in functional magnetic resonance imaging (fMRI) studies and comparing the congruency effect (i.e., different brain responses to congruent versus incongruent audiovisual conditions; commonly considered an indicator of multisensory integration), altered activations in both children and adults with developmental dyslexia have been reported. However, the current pieces of evidence are almost restricted to alphabetic languages. Whether such processes are also impaired in dyslexia in non-alphabetic languages (e.g., Chinese) with different linguistic characteristics remains open. Against this background, we adopted a similar fMRI audiovisual paradigm with simple high-frequency pictographic characters and pinyin (an alphabetic system helping individuals learn new character’s pronunciation) as materials to examine the possible dysfunctions in Chinese school-aged children with dyslexia. Of note, while the two types of scripts are both fundamental for children’s reading acquisition in Mainland China, they have quite different linguistic properties, e.g., deep versus shallow transparencies. Four experimental conditions (auditory-only, visual-only, audiovisual congruent, audiovisual incongruent) were created with each type of script. During the fMRI scan, a simple target detection task was used to help participants hold their attention. We were particularly interested in the group differences in the congruency effect (i.e., audiovisual congruent against incongruent condition) and congruency-reading correlations in the data analysis. Unexpectedly, we found no region displaying significant group differences on the congruency effect survived the whole-brain multiple corrections in either experiment. However, differences were observed in the congruency-reading associations between the dyslexic and typical controls. Specifically, in the character experiment, the congruency effect in the left IFG was correlated with morphological awareness in the control group but with rapid naming in the dyslexic group. This pattern suggests that the affected children might have not yet developed an automatic grapho-semantic mapping as their typically developing peers do, but instead more access to the articulatory information during implicit character processing. In the pinyin experiment, the congruency effects in the bilateral STC and left OTC were positively associated with oral word reading fluency in the control group, whereas children with dyslexia showed negative associations. This pattern indicates dysfunctional recruitment of the grapho-phonological circuitry in dyslexia during pinyin processing, which may have been impeding their character learning. To summarize, this fMRI study investigated the possible impaired neurofunctional basis of print-sound integration in Chinese children with dyslexia. The findings reveal that although dyslexic children recruit similar neural networks for print-sound processing, they may use these neural resources differently compared with their typical peers. Given that developing fluent reading relies on well-established grapho-phonological and grapho-semantic mappings, this study also suggests Chinese children with dyslexia may have impaired neural circuitries underlying both processes.