中国科学家最新《Cell》子刊文章

生物通报道，香港大学国家重点脑科学与认知学实验室，双语学研究系，北京306医院的科学家在最新的Cell子刊《Current Biology》上发表研究文章Developmental dyslexia is characterized by the co-existence of visuospatial and phonological disorders in Chinese children。

 

文章作者包括：香港大学的Wai Ting Siok和John A. Spinks、北京医院的Zhen Jin，以及香港大学的Li Hai Tan。

 

汉语无疑是世界上比较难学的语种，说汉语的儿童患诵读困难症与说英语的儿童情况明显不同，而且前者或许更加复杂和严重。这些差异可以在大脑中观察到，也可以在说汉语的儿童对于视觉语言和口头语言的测试成绩中观察到。

 

香港大学的Wai Ting Siok解释说，英语的诵读困难症包括了一种"音系障碍"，意思是患该病的人们在探测或操纵口语的声音结构方面有困难，而这反过来又导致了把语音映射成字母的困难。相比之下，这些新的发现表明汉语的发展性诵读障碍其实是两种障碍：一种是视觉空间缺陷，而另一种是音系障碍。

 

Siok和她的同事Li Hai Tan说，这种差异可以追溯到两种语言的特征。"在英语中，形成了可视的词语的字母是可发音的，因此通过使用字母到语音的转换规则就可以进行英语词的发音，"Siok说。"书面汉语把图形（也就是汉字）映射成意义；汉字拥有一些复杂的笔画，组成了一个方块的构造，而且必须死记硬背它们的发音。这种特性提示，为了激活汉字的音系和语义信息，视觉系统必须进行细粒度的视觉空间分析。因此，在汉语诵读障碍症中，有障碍的音系处理可能常常与异常的视觉空间处理共存。"

 

这组科学家要求正常和有诵读困难症的汉语读者判断视觉刺激的物理尺寸，结果发现了正常的读者的表现显著优于诵读困难症的读者。大脑扫描显示，与正常读者相比，诵读困难症患者的大脑中已知用于调控视觉空间处理的部分的激活更弱。Siok说，关键在于，大多数有视觉空间问题的汉语诵读困难症患者也表现出了音系处理障碍，这是由他们在与音系有关的判断押韵的任务中的不良表现证明的，这提示了两种障碍的共存。

 

"我们的研究首次证明了视觉处理和音系障碍在诵读困难症患者身上共存，"Tan说，这对目前解释发展性诵读障碍症的理论提出了一个挑战。"我们的结果强有力地表明，需要一个拥有足够余地的统一的理论去容纳观察到的机能障碍的充分复杂性和涉及到诵读缺陷的各个大脑系统之间的相互作用。

 

生物通推荐原文检索

Developmental dyslexia is characterized by the co-existence of visuospatial and phonological disorders in Chinese children

 

Wai Ting Siok1, 2, John A. Spinks1, 3, Zhen Jin4 and Li Hai Tan1, 2, 

 

1 State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China

2 Department of Linguistics, The University of Hong Kong, Pokfulam Road, Hong Kong, China

3 Vice-Chancellor's Office, The University of Hong Kong, Pokfulam Road, Hong Kong, China

4 Beijing 306 Hospital, Beijing 100101, China

 

【Summary】

Developmental dyslexia is a neurological condition that is characterized by severe impairment in reading skill acquisition in people with adequate intelligence and typical schooling [1,2,3]. For English readers, reading impairment is critically associated with a phonological processing disorder [3,4,5], which may co-occur with an orthographic (visual word form) processing deficit [6], but not with a general visual processing dysfunction in most dyslexics [7]. The pathophysiology of dyslexia varies across languages [8]: for instance, unlike English, written Chinese maps visually intricate graphic forms (characters) onto meanings; pronunciation of Chinese characters must be rote memorized. This suggests that, in Chinese, a fine-grained visuospatial analysis must be performed to activate characters' phonology and meaning; consequently, disordered phonological processing may commonly co-exist with abnormal visuospatial processing in Chinese dyslexia. To test this hypothesis, we conducted an fMRI experiment in which 12 Chinese dyslexics, shown previously [9] to exhibit a phonological disorder, performed a physical size judgment measuring visuospatial dimensions. Compared with 12 control subjects, the dyslexics showed weaker activations in left intraparietal sulcus (IPS) mediating visuospatial processing. Analyses of individual dyslexics' performances further suggest that developmental dyslexia in Chinese is commonly associated with the co-existence of a visuospatial deficit and a phonological disorder.