Developmental dyslexia in Chinese and English populations: dissociating the effect of dyslexia from language differences

Abstract

Previous neuroimaging studies have suggested that developmental dyslexia has a different neural basis in Chinese and English populations because of known differences in the processing demands of the Chinese and English writing systems. Here, using functional magnetic resonance imaging, we provide the first direct statistically based investigation into how the effect of dyslexia on brain activation is influenced by the Chinese and English writing systems. Brain activation for semantic decisions on written words was compared in English dyslexics, Chinese dyslexics, English normal readers and Chinese normal readers, while controlling for all other experimental parameters. By investigating the effects of dyslexia and language in one study, we show common activation in Chinese and English dyslexics despite different activation in Chinese versus English normal readers. The effect of dyslexia in both languages was observed as less than normal activation in the left angular gyrus and in left middle frontal, posterior temporal and occipitotemporal regions. Differences in Chinese and English normal reading were observed as increased activation for Chinese relative to English in the left inferior frontal sulcus; and increased activation for English relative to Chinese in the left posterior superior temporal sulcus. These cultural differences were not observed in dyslexics who activated both left inferior frontal sulcus and left posterior superior temporal sulcus, consistent with the use of culturally independent strategies when reading is less efficient. By dissociating the effect of dyslexia from differences in Chinese and English normal reading, our results reconcile brain activation results with a substantial body of behavioural studies showing commonalities in the cognitive manifestation of dyslexia in Chinese and English populations. They also demonstrate the influence of cognitive ability and learning environment on a common neural system for reading.

Universal Reading Processes Are Modulated by Language and Writing System

“…Adding complexity to the picture is evidence that whereas Chinese reading, compared with alphabetic reading, engages distinctive areas in normal readers, Chinese dyslexics show activation patterns that are highly overlapping with what is shown by alphabetic dyslexics (Hu et al, 2010). …”

Centro-parietal N200: An event-related potential component specific to Chinese visual word recognition

“…Linguists are also starting to use cognitive neuroscience methods to examine traditional linguistic topics [9]. However, with about three decades of research, including recent work in cognitive neuroscience, no reliable and well-accepted neural markers have been identified to distinguish word recognition across Chinese and other alphabetic scripts such as English [10][11][12][13][14]. Occasional reports of cross-script differences in brain activation are either not well-replicated or uncertain as to whether they do reflect unique processing for Chinese word recognition.…”

China’s language input system in the digital age affects children’s reading development

“…For example, children's awareness of the phonological structure of speech sounds and their knowledge of letter-sound correspondences play a pivotal role in reading development in English and other alphabetic languages, and reading instruction and remediation programs have therefore centered on phonological training (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). For Chinese readers, children's reading acquisition begins with a demanding visuospatial analysis of characters' graphic forms composed of strokes and subcharacter components that are packed into a square (2,17,18), followed by rote memory of arduous lexical mappings of orthography to phonology, orthography to meaning, and phonology to meaning (19,20). A prevalent strategy in facilitating the development of these mappings is handwriting, which requires children to repeatedly copy single characters to help them to elaborate the visuo-orthographic analysis of characters and to establish their representation in longterm memory (21)(22)(23)(24)(25).…”