Neurofunctional mechanisms underlying audiovisual integration of characters and pinyin in Chinese children

Efficient integration of grapheme and phoneme is crucial for reading development in alphabetic languages, and superior temporal cortex (STC) has been demonstrated to be the most critical region for this process. To determine whether a similar neural mechanism underlies such processing in non-alphabetic languages, and to explore its relationship with reading, we conducted a functional magnetic resonance imaging study in typically developing Chinese children. Highly frequent pictographic characters and pinyin, a transparent alphabetic coding system that assists individuals to learn the pronunciation of new characters were investigated. In support of the orthographic depth hypothesis developed in alphabetic languages, reverse congruency effect (i.e., higher activation in incongruent condition compared to congruent condition) was identified in the left inferior frontal gyrus (IFG) and bilateral STC for character (deep orthography) conditions. Furthermore, correlation analysis revealed that the congruency contrast in the left IFG was associated with proficiency in reading comprehension and morphological awareness, suggesting reading-related semantic access during the implicit integration of multisensory information regarding characters. For pinyin (shallow orthography) conditions, while no regions showed a significant congruency effect at the group level in either direction, the congruency contrast in the left superior temporal gyrus was positively correlated with oral reading performance. This observation is consistent with findings in transparent scripts on reading disorders. Taken together, these results support and generalize the orthographic depth hypothesis to a logographic language, highlight the role of the left IFG in character-syllable integration, and underscore the role pinyin could play in developing fluent reading in Chinese children.