认知与发展心理学研究室知识库

发展性阅读障碍是指个体在获得阅读技能方面存在特殊困难，且这种困难不能单纯的归因于智力缺陷、视敏度缺陷或者教育缺失。对于其成因目前还没有明确的结论。拼音文字发展性阅读障碍的视觉空间注意缺陷理论认为，视觉大细胞一背侧通路的缺陷会导致发展性阅读障碍的视觉空间注意缺陷，影响了阅读过程中语音解码的能力，进而导致语音缺陷和阅读困难。汉语是一种特殊的文字，不存在拼音文字中形素到音素的语音解码过程，字形结构也非常复杂，需要更多的视觉空间加工。目前对汉语发展性阅读障碍儿童的研究还较少，结果也不一致。本研究的目的是从行为和脑两个层面来考察汉语发展性阅读障碍儿童的视觉空间注意能力，并考察与哪些阅读技能有关。
研究一通过线索范式和视觉搜索范式，通过与同年龄对照组对比，从行为层面考察汉语发展性阅读障碍儿童covert visual spatial attention和。vert visualspatial attention是否存在缺陷，结果发现，汉语发展性阅读障碍儿童没有表现出covert visual spatial attention缺陷，这与拼音文字的结果不一致。在视觉搜索范式中，汉语发展性阅读障碍儿童表现出对方向搜索和联合搜索的困难。这表明汉语发展性阅读障碍儿童存在overt visual spatial attention的缺陷，并且可能存在对方向的早期视觉加工困难。汉语DD儿童的overt visual spatial attention能力与其阅读技能存在相关。主要表现在方向搜索能力与阅读流畅性、快速命名和正字法技能等阅读技能存在相关，联合搜索能力与正字法技能有关。
研究二采用静息态磁共振功能成像和结构磁共振成像的方法，考察汉语发展性阅读障碍儿童背侧和腹侧注意网络的脑区是否存在功能和结构缺陷。静息态fMRI的结果发现，对局部脑区，汉语发展性阅读障碍儿童的背侧注意网络和腹侧注意网络的脑区都存在异常。从静息态功能连接的角度，汉语发展性阅读障碍儿童背侧注意网络内部、背侧与腹侧注意网络之间，以及与阅读网络的连接都存在异常。背侧注意网络与阅读网络之间的连接与阅读流畅性存在相关，而腹侧注意网络与阅读网络的连接和快速命名存在相关。脑结构的研究发现，汉语发展性阅读障碍儿童的背侧注意网络的脑区同时存在皮层厚度异常，并且这种异常与阅读流畅性、正字法技能等阅读技能存在相关。
综合以上结果可以看出，汉语发展性阅读障碍儿童存在视觉空间注意缺陷，但仅限于overt visual spatial attention。此外，汉语发展性阅读障碍儿童在背侧和腹侧注意网络存在广泛的功能和结构的异常，并且这种异常与其阅读技能存在相关。

Developmental dyslexia is defined as a reading skills acquisition impairment despite normal intelligence, normal visual acuity and adequate learning opportunities.
The cause of the dyslexia was still unknown. A substantial number of research have demonstrated that alphabetic language speaking children with dyslexia have deficit in visual-spatial attention, especially in rapid orienting of the attentional spotlight. And their visual-spatial attention is correlated with their phonological decoding deficit. Chinese, as a logographic language, is charaterized with several diffences to alphabetic languages. Chinese script is known as addressed phonology, which means that a Chinese character directly maps to a whole morpheme syllable.Thus, there is no letter-by-letter phonological decoding when reading Chinese.Besides, Chinese characters also have higher visual-spatial complexity than alphabetic language. There is more visual processing in reading Chinese than reading alphabetic language script. To date, few studies have explored the visual spatial attention of Chinese dyslexia. The present study adopted behavioral measurements and functional magnetic resonance imaging (fMRn technique to systematically investigate the visual spatial attention in Chinese dyslexic children and the relationship between the visual spatial attention and the Chinese reading skills.
The first research explored the covert attention and the overt attention of Chinese dyslexic children using the cue paradigm and the visual search paradigm respectively. The results showed that the Chinese dyslexic children only exhibited an impairment in overt attention, which was inconsistent with the results of the alphabetic language studies. The Chinese dyslexic children showed difficulties in orientation searching and the conjunction searching tasks, indicating that the Chinese dyslexic children have impairment in early visual processing of orientation and overt attention. We also found that the overt attention was correlated with multiple Chinese reading skills, such as the reading fluency, rapid naming and orthographic skill.
The second research explored the neural basis of the visual spatial attention in Chinese dyslexic children. Using the resting一state fMRI, the present research found that the Chinese dyslexia showed the abnomal amplitude of low-frequency fluctuation (ALFF) or regional homogeneity (ReHo) in several brain regions in dorsal attention network and ventral attention network. The results also showed that the strength of resting一state functional connectivity (RSFC) within the dorsal attention network and between the dorsal attention network and the ventral attention network was abnormal in Chinese dyslexia. The RSFCs between the brain regions in attention network and reading network was also abnormal in Chinese dyslexia. The RSFC between the dorsal attention network and the reading network was correlated with the reading fluency. The RSFC between the ventral attention network and the reading network was correlated with the rapid naming. The present research also found that the cortical thickness in brain regions of dorsal attention network increased in Chinese dyslexia. And the cortical thickness in those brain regions were correlated with the reading fluency and orthographic skill.
In conclusion, the Chinese dyslexia exhibits the impairment in visual spatial attention, but the impairment is restricted to overt attention. The Chinese dyslexia also exhibits both functional and structural impairment in dorsal and ventral attention network. In addition, the impairment in visual spatial attention was correlated with multiple Chinese reading skills, such as reading fluency and rapid naming.