中国科学院心理研究所机构知识库

发展性阅读障碍是一种有遗传基础的神经发育不良引起的疾病，表现为一种阅读学习的持续困难。研究者试图在基因水平，神经生物水平和认知水平描述阅读障碍的特征，以期揭示掩藏于各不同水平间的真正原因。汉语为一种独特的表意文字，汉字的二维构型使其具有显著的图形特征；声旁具有 一定的表音功能；形旁具有表示字义类属的能力，这些特点使汉字的形音义关系与拼音文字有很大差异；因而引起研究者的极大兴趣。本实验综合运用实验心理学的研究方法和神经科学的研究手段 ERP 技术，从神经心理学的角度，考察汉语发展性阅读障碍是否在视听觉功能和语音分辨方面有与拼音文字相应的表现形式，并结合 Franck 理论假说，进一步深入分析它们之间是否存在共同的原因，有共同的生理基础，为其汉语阅读障碍的研究及理论的发展提供电生理学证据。

本论文实验结果发现汉语阅读障碍在视听觉功能上有非语言特异性的感知觉加工缺陷：阅读障碍儿童在完成视觉任务时成绩稍差，反应时延长，ERP 波形成分的峰潜伏期也延长，波幅降低，尤其是左侧枕叶视皮层对右侧视野投射信号的加工效能差，峰潜伏期与正常儿童的差异更大。而我们使用的视觉刺激是巨细胞系统加工的适宜刺激，因而可以说明汉语阅读障碍儿童中也存在视觉巨细胞系统功能缺陷，而且，可能有其独特性，表现为枕叶的左侧视皮质功能差异，这是首次报道阅读障碍儿童枕叶视皮质的左右差异。阅读障碍儿童完成听觉分辨任务的反应时虽然与正常儿童没有显著的差异，从行为水平观察，可能推断出阅读障碍儿童听觉分辨的功能与正常儿童没有差异，但是从正确率分析可以明显地看出，他们对听觉分辨的效能比正常儿童低；尤其 是在听觉相关电位中的表现，基本 与视觉相关电位中的变化一致，也是峰潜伏期延长，波幅降低。这说明汉语阅读障碍儿童的听觉功能也可能有缺陷。阅读障碍儿童在视听觉双通道信号整合的加工上仍表现出 ERP 波形成分的峰潜伏期延长，波幅较低的现象；这说明阅读障碍儿童在视听觉整合中也可能存在缺陷，综合这三方面的结果，可以推论阅读障碍者可能对一般的信息进行感知觉加工的效能弱。

汉语阅读障碍儿童在同音字判断任务中表现出有语音意识缺陷：本实验结果表明，阅读障碍儿童完成同音字判断任务的正确率与正常儿童有显著的差异,主要表现为对字形字音的分析缺陷，而语义的加工水平正常。阅读障碍儿童对假字的加工和形似同音字的加工产生的 ERP 波形均与正常儿童有显著差异。这种差异尤其在左脑更明显，可能是由于声旁的干扰对读音提取的错误线索作用，而使得阅读障碍儿童必须对读音提取策略作出调整，而增加了颞叶和额叶的语音分析，所以形似音异字比形似同音字的波幅更高。

本实验结果一定程度上支持 Franck 对阅读障碍的病因的新的理论解释。事件相关脑电研究提供的结果显示，汉语阅读障碍儿童在视听觉功能和语音意识上表现出的神经心理学特征基本是一致的，与正常儿童的差异均表 现为峰潜伏期延长，波幅降低的现象。结合 Franck 的理论，我们作出对汉语阅读障碍形成原因的推论：汉语阅读障碍行为表现多种多样，这些变异性可能有一些共同的神经心理基础；可能由于出生前神经的异常发育，遗传的异常或环境的影响而导致的大脑左右两半球功能与正常儿童的差异，尤其是左半球的功能差异引起其对语言加工的缺陷，可能伴随出现视听觉等基本的感知觉功能障碍。

Developmental dyslexia is a mild hereditary neurological disorder that manifests as a persistent difficulty in learning to read in children with normal intellectual functioning and educational opportunities. One notable aspect of dyslexia is the variety of symptoms. This plurality of symptoms has led to two broad approaches to dyslexia. One has been to concentrate on one particular cognitive symptom as the phonological theory of dyslexia that showed a specific deficit in the representation and processing of speech sounds (grapheme–phoneme correspondences). The alternative theoretical approach gives a primary explanatory role to the sensory and/or motor symptoms. This approach has led to the formulation of theories of dyslexia tracing the causes of reading disability back to auditory (temporal) processing deficit, visual (magnocellular) dysfunction and/or motor (cerebellar) dysfunction.

Chinese language has attracted a great deal of interest among researchers as a unique language. All Chinese languages use a nonalphabetic script, which is a relatively arbitrary system for mapping orthography to phonology. This feature of Chinese means that homophony is prevalent, and for a reader the skill of phonological awareness, specifically at the level of the onset and the rime is a critical capacity of learning spoken and written Chinese words. The phonetic component of a compound is itself often a character (and thus represents a syllable), which potentially provide information about the pronunciation of the whole compound via a lexical reading process. It would therefore be interesting to investigate whether dyslexic children reading nonalphabetic orthographies exhibit the same pattern of deficits as do alphabetic counterparts.

By integrating the behavior and ERP measure, the goal of the present dissertation was to systematically reveal the neuropsychological development law of two aspects including language and perceptivity in dyslexia and normal children.

The objective of experiment 1 is designed for exploring the neuropsychological feature of development dyslexia, especially in visual sensitivity of magnocellular system and hemispheric lateralization using the high temporal frequencies dynamic visual stimuli presented by lateral visual field. The results showed as follows: Firstly, the pattern of dyslexia children responded to the task of lateral visual field stimulation was consistent with that of normal children. There were significant interaction effects between task and hemisphere. Secondly, the latency of P120 component and the amplitudes of N60 and N180 have remarkable differences between normal child and dyslexia, especially in the latency of P120 in electrode O1. We made such conclusions: The occipital processing from right visual field stimulation showed a predominance of left cortex, while processing the left stimulus had preference for right occipital, in other word, lateral visual field stimulation active the contralateral occipital. In Chinese dyslexia that dyslexia suffered from the M pathway deficits as their contemporaries who may have the obstacle to read alphabetic writing. A left occipital cortex dysfunction is thought to be the neurological basis underlying the Chinese dyslexics M' deficit. Compared with the control, development of magnocellular system in dyslexia may delay, and the development of interhemispheric asymmetry was disregulated, especially in left occipital. The aberrant development of magnocellular system and interhemispheric asymmetry was the main neuropsychologic feature of magnoccelullar system in Chinese dyslexia.

The experiment 2 is aimed to explore the neuropsychological feature of developmental dyslexia, especially in auditory sensitivity using 500Hz and 1000Hz pure tones auditory stimuli. The results were following: Firstly, auditory-related brain potential was a large negative wave form, which could include four waves, respectively as P60, N160, P200, and N240. Secondly, there is a significantly left-right hemispheric difference in processing pure tone. Thirdly, comparing with normal, the auditory-related brain potential of dyslexia expressed as the delay of latency and the descent of amplitude. We thought that the development of auditory system in dyslexia maybe more delays than normal children. The significant delay of latency and the marked descent of amplitude perhaps is the main neuropsychological character in auditory system of dyslexia.

The goal of experiment 3 was to explore the neuropsychological feature of developmental dyslexia, especially in audio-visual integration using the combinations of lateral visual stimuli with pure tones auditory stimuli. The results showed as follow: Firstly, the significant main effect exits between two children in auditory-related brain potential such as P60, N160. Secondly, the main effect of latency of P110 is significant. The latency of dyslexia is more delayed markedly than that of normal. Thirdly, the accuracy of dyslexia is lower than that of normal but the response time doesn’t reach the significant level. The conclusions were made: The processing of audio-visual integration of development dyslexia is in according with the model of interaction. The significant delay of latency and the marked descent of amplitude perhaps are the main neuropsychological character in dyslexia. On the other hand, the behavior results of dyslexia differ from single modal. Those results elucidate dyslexia may have limited mental resource that they couldn’t deal with so much signals.

The experiment 4 was designed to explore whether the phonology plays an important role in mental lexicon development and whether phonological deficit exists in Chinese dyslexic children when operating the task of homophony judgment. The data about Chinese dyslexia show that the dyslexia has deficits in orthography and phonology while capacity of semantic is good. There were significant differences in accuracy for homophone judgment between two groups; the accuracy of dyslexia was lower. Secondly, the phonetic radicle played an important role as a cue in retrieval the phonology of a compound, the disturbance and promotion of phonetic radicle also showed a significant difference. Thirdly, there was a significant difference in the processing of pseudo-characters and orthography-similar-homophony characters. This difference showed more marked in right-hemisphere temporal and frontal cortex. Fourthly, dyslexia children showed longer latency and lower amplitude in ERP waveform component. These results suggest that phonologic awareness play an important role in Chinese and Chinese dyslexia showed the phonological deficit.

To sum up, there seem to be multiple causes for reading disabilities in Chinese. Chinese dyslexia children can have impairment in one or more of the domains of language and perceptivity as their alphabetic counterparts.