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Frontoparietal interactions underlay visuospatial orthographic processes in Chinese reading
Poster E124 in Poster Session E, Thursday, October 26, 10:15 am - 12:00 pm CEST, Espace Vieux-Port
Pedro M. Paz-Alonso1, Jianqin Wang2, Huipìng Wang3, Yanjun Wei2; 1BCBL. Basque Center on Cognition, Brain and Language, 2Key Laboratory of the Cognitive Science of Language (Beijing Language and Culture University), Ministry of Education, Beijing, China, 3Center for the Cognitive Science of Language, Beijing Language and Culture University, Beijing, China
Previous neuroimaging research has started to unveil the neural correlates of orthographic, phonological, and semantic processing of Chinese reading. As a logographic writing system, Chinese reading encompasses processing visuospatial orthographic properties. To date, most of the neuroimaing research in processing Chinese characters have focused on phonological and semantic aspects rather than on visuospatial orthographic processes. Here, we sought to investigate the functional correlates supporting visuospatial orthographic processes relative to semantic and phonological processes in Chinese reading. We conducted a functional MRI single-character reading study in Chinese, in which 35 right-handed native Chinese young adults were asked to make orthographic judgments (i.e., whether the orthography of a character contains a radical "又", such as a target "对"), phonological judgments (i.e., whether the phonology of a character contains the vowel of "ong", such as "红, /hong2/"), and semantic judgments (i.e., whether the meaning of a character is an animal, such as "狗, dog"). Stimuli were visually presented in separate task-specific (orthographic, phonological, semantic) activation blocks of 11-13 s, that were alternated with rest-fixation blocks of 12 s. Conjunction analyses at the whole-brain level revealed that single-character reading across the three tasks recruited a frontal-parietal-temporal network in the left hemisphere and ventral occipitotemporal cortex (vOTC) bilaterally. Whole-brain contrasts between the three tasks showed that the brain activation for orthographic processing, compared to semantic processing, was mainly right lateralized. Also, activations associated with semantic processing occurred bilaterally but was more left lateralized for semantic versus phonological processing. Regions of interest (ROIs) analyses based on previous meta-analyses in Chinese reading revealed similar engagement profile across areas with stronger activation for semantic and orthographic processing than phonological processing. Of interest, among the regions examined, only the left pars triangularis (Tri) showed stronger engagement for semantic processing relative to orthographic and phonological processing. Time-course analysis conducted to examine temporal differences in the profile of activation among three tasks revealed a Task X Time-window interaction for left superior parietal gyrus (SPG), with initial activation being stronger for semantic than orthographic and phonological processing, and a significant increase for later activation in the orthographic processing of this region that reaches up to the same extent of the semantic processing but goes up higher than phonological processing. Both pairwise and whole-brain functional connectivity (FC) revealed that the MFG-SPG and vOTC-SPG FC was stronger in orthographic processing than semantic processing. In addition, stronger vOTC-SPG FC was associated with weaker vOTC activation and SPG-MFG FC was also associated with weaker MFG engagement. In sum, our study revealed that visuospatial orthographic processes in Chinese reading involves stronger right hemisphere engagement, including right vOTC, as well as a left-lateralized dorsal frontoparietal network that interacts with vOTC to orthographically process Chinese characters. Stronger connectivity in this left vOTC-SPG-MFG network is associated with reduced regional engagement, which suggest that processing visuospatial orthographic processes in Chinese rely on functional interactions among regions rather than of local processes taking place in each of them.
Topic Areas: Reading,