汉语阅读障碍儿童汉字识别过程中脑血氧的变化

背景:阅读障碍是学习困难研究中最为常见的,可影响儿童的行为、认知、情感、社会适应等方面,严重阻碍儿童知识的获得和能力的提高。目的:研究汉语阅读障碍儿童汉字认知过程左前额叶皮层血氧变化规律,探讨儿童阅读障碍的神经生理基础。设计:病例对照实验。单位:华中科技大学同济医学院公共卫生学院儿少卫生与妇幼保健学系。对象:实验于2003-06/09在华中科技大学完成。选择45名武汉市3～5年级小学生为研究对象,年龄在8～12岁,均为右利手。其中汉语阅读障碍儿童26名(阅读障碍组),符合ICD-10定义的标准;非阅读障碍儿童19名(对照组)。所有对象均取得本人及父母(监护人)的知情同意。方法:应用功能性近红外光学成像技术,检测汉语阅读障碍和非阅读障碍儿童汉字初级加工(包括被动视觉呈现汉字,汉字朗读,动词联想)及再加工(包括词语输出和语义联想)过程左前额叶脑血氧含量的变化。主要观察指标:两组汉字初级加工及再加工过程中脑血氧含量的变化。结果:纳入阅读障碍儿童26名,非阅读障碍儿童19名,均进入结果分析。①汉字初级加工时血氧含量的变化:被动视觉呈现汉字:A,B,C通道上,阅读障碍组血氧含量均高于对照组(0.3780,0.1346;0.0858,0.0519;0.1093,0.0692,P<0.05),D通道上,阅读障碍组和对照组血氧含量差异不明显(P>0.05);汉字朗读:A、B、C、D通道上,阅读障碍组血氧含量高于对照组,但差异不明显(P>0.05);动词联想:在A、C通道上,阅读障碍组血氧含量高于对照组(0.4112,0.1397;0.1413,0.0784,P<0.05),在B、D通道上,阅读障碍组与对照组血氧含量差异不明显(P>0.05)。②汉字再加工过程血氧含量的变化:词语输出过程中,阅读障碍组的血氧含量变化量明显低于对照组(-0.0257,0.0890,F=16.25,P<0.01);语义联想过程中,阅读障碍组的血氧含量变化量明显高于对照组(0.0730,-0.0721,F=15.59,P<0.01)。结论:汉字认知过程阅读障碍儿童左前额叶皮层虽然激活,但相对正常儿童,激活的程度和激活模式均有差异熏提示特定脑区功能异常可能是阅读障碍发生的生物学基础。

Changes of regional cerebral blood oxygenation in recognizing Chinese characters in children with Chinese dyslexia

BACKGROUND: Dyslexia is the most common in the study of learning disabilities, it can affect various aspects of children, including behaviors,cognition, emotion, social adaptation, etc., and seriously block their obtaining of knowledge and improvement of ability in children.OBJECTIVE: To study the changing law of regional cerebral blood oxygenation in children with Chinese dyslexia in the process of recognizing Chinese characters, and investigate the neurophysiological basis of dyslexia in children.DESIGN: A case-control study.SETTING: Department of Child and Adolescent Health and Maternal Care, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology.PARTICIPANTS: The study was carried out in Huazhong University of Science and Technology from June to September in 2003. Forty-five primary students of 8 to 12 years old, who were grade 3 to 5 in Wuhan city,were enrolled in this study, including 26 dyslexic children (dyslexia group)and 19 normal readers (control group). All the enrolled children were righthanded. Informed consents were obtained from all the participants and their parents (guardians) after explanation of aims and steps of this study.METHODS: The functional near-infrared imager (fNIRI) was applied to detect the changes of cerebral blood oxygenation in left prefrontal lobe of dyslexic children and normal children in the primary processing (viewing passively, reading aloud, producing an action word) and secondary processing of Chinese characters (outputting task, action words association) of Chinese characters.MAIN OUTCOME MEASURES: The changes of cerebral blood oxygenation in the primary processing and secondary processing of Chinese characters were observed in both groups.RESULTS: All the 26 children with Chinese dyslexia and 19 normal children were involved in the analysis of results. ① Changes of the contents of blood oxygenation in the primary processing of Chinese characters:When viewing the Chinese characters passively, the contents of blood oxygenation on channel A, B and C were all higher in the dyslexia group than in the control group (0.378 0, 0.134 6; 0.085 8, 0.051 9; 0.109 3, 0.069 2;P ＜ 0.05); there was no obvious difference on channel D between the two groups (P ＞ 0.05). When reading aloud, the contents of blood oxygenation on channel A, B, C and D were all unobviously higher in the dyslexia group than in the control group (P ＞ 0.05). In the process of generating action words, the contents of blood oxygenation on channels A and C were all higher in the dyslexia group than in the control group (0.411 2, 0.139 7;0.141 3, 0.078 4; P ＜ 0.05), and there were no obvious differences on channels B and D between the two groups (P ＞ 0.05). ② Changes of the contents of blood oxygenation in the secondary processing of Chinese characters: In the process of outputting task, the changes of blood oxygenation was lower in the dyslexia group than in the control group (-0.025 7, 0.089 0,F=16.25, P ＜ 0.01); In the process of action words association, the changes of blood oxygenation was obviously higher in the dyslexia group than in the control group (0.073 0, -0.072 1, F=15.59, P ＜ 0.01).CONCLUSION: The cortexes of left prefrontal lobe in dyslexic children are activated in the process of recognizing Chinese characters, but the degree and pattern of activation are different from those of normal children.The functional abnormalities of specific brain area may be the biological basis of Chinese dyslexia.Song RR, Wu HR.Changes of regional cerebral blood oxygenation in recognizing Chinese characters in children with Chinese dyslexia.