title: Altered brain structure in Chinese dyslexic children.
abstract: Due to the logographic nature of the writing system, learning to read Chinese places heavy demands on encoding of orthographic forms through rote memorization. Moreover, phonology has to often be retrieved from memory during reading because of the inconsistent mapping between characters and their pronunciations. Using optimized voxel-based morphometry, we examined differences in volumetrics between children with reading disability (RD, 10-12 years old) and age-matched typically developing (TD) children. Our study shows reduced gray matter volume (GMV) for RD in right inferior occipital gyrus and left inferior frontal gyrus, consistent with previous studies suggesting that Chinese dyslexics have deficits in orthographic and phonological processing. The deficit in phonological processing was further supported by reductions in white matter volumes (WMV) in left precentral gyrus. Greater deficits in ortho-phonological processing may be associated with semantic compensation, as lower skill RD children showed greater GMV in anterior temporal cortex, even though as a group they showed less GMV in this region compared to TD. Perhaps most interestingly, we showed reduced GMV in bilateral ventromedial prefrontal cortices (vmPFC) and this was correlated with reductions in WMV within vmPFC, suggesting that RD have deficits in memory retrieval. Moreover, these GMV alterations in vmPFC for the RD were correlated with alterations in right parahippocampal gyrus, which also showed a reduced GMV, suggesting that RD have a correlated deficit in memory encoding. Our results are consistent with previous studies suggesting that Chinese dyslexics have deficits in visuo-orthographic and phonological processing, but our study importantly suggests deficits in memory encoding and retrieval, perhaps due to the unique demands of the Chinese writing system.
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China. lilyliu.bnu@gmail.com
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Wenping
authors.initials: W
authors.lastname: You
authors.forename: Wenjing
authors.initials: W
authors.lastname: Wang
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Guo
authors.forename: Danling
authors.initials: D
authors.lastname: Peng
authors.forename: James
authors.initials: J
authors.lastname: Booth
mesh_terms: D000293:Adolescent; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D002648:Child; D002681:China; D004410:Dyslexia / Q000473:pathology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D011932:Reading; D012044:Regression Analysis