Department of Neuropsychology, University of Zurich, Switzerland.
Int J Psychophysiol. 2010 Jul;77(1):59-69. doi: 10.1016/j.ijpsycho.2010.04.003. Epub 2010 Apr 24.
The present Event-Related Potential (ERP) study aimed to investigate group differences in the early processing stages of 36 dyslexic and 24 non-dyslexic 8-12 year old children performing a lexical decision (word/pseudoword judgment) task. Our data showed larger amplitudes of negative-going waveforms in non-dyslexic children than dyslexic children over occipital/occipitotemporal electrodes at about 220 ms after stimulus onset. This electrophysiological response has previously been identified in adult readers and labeled as the N170 component. Notably, as reflected by the topographic maps children irrespective of group processed the linguistic stimuli bilaterally and we did not observe any differences in ERP parameters in words and pseudowords within groups. Contrarily, behavioral responses indicate that words were more quickly recognized than pseudowords irrespective of group. By applying post-hoc ROI analyses based on a source estimation approach (sLORETA) we observed that non-dyslexic participants, when compared to dyslexic children, demonstrated significantly stronger current density over the left hemispheric inferior temporal lobe when processing pseudowords. We concluded that impaired reading is reflected by the decreased amplitude of the early lexical component N170. The lack of a left hemispheric processing preference in both groups and similar activation for words and pseudowords can be considered a lack of reading experience and less established reading system in children. Our results indicate that dyslexic children commit fewer specialized neuronal circuits for processing print and confirm the reasoning that acquiring reading skills requires cortical reorganization over occipitotemporal regions.
本事件相关电位（ERP）研究旨在调查 36 名阅读障碍儿童和 24 名非阅读障碍 8-12 岁儿童在执行词汇判断（单词/伪词判断）任务时早期加工阶段的组间差异。我们的数据显示，在刺激后约 220 毫秒，非阅读障碍儿童的负向波幅比阅读障碍儿童更大，在枕叶/枕颞电极上。这种电生理反应以前在成年读者中被发现，并被标记为 N170 成分。值得注意的是，正如地形图所示，无论组间如何，儿童都双侧处理语言刺激，我们在组内的单词和伪词中没有观察到任何 ERP 参数差异。相反，行为反应表明，无论组间如何，单词的识别速度都快于伪词。通过应用基于源估计方法（sLORETA）的事后 ROI 分析，我们观察到，与阅读障碍儿童相比，非阅读障碍参与者在处理伪词时，左半球下颞叶的电流密度明显更强。我们得出的结论是，阅读障碍反映了早期词汇成分 N170 的振幅降低。两组都缺乏左半球处理偏好，并且对单词和伪词的相似激活可以被认为是缺乏阅读经验和儿童阅读系统建立不足。我们的结果表明，阅读障碍儿童在处理印刷品时较少使用专门的神经元回路，并证实了这样的推理，即获得阅读技能需要在枕颞区域进行皮质重组。
