Schulz Enrico, Maurer Urs, van der Mark Sanne, Bucher Kerstin, Brem Silvia, Martin Ernst, Brandeis Daniel
Department of Child and Adolescent Psychiatry, University of Zurich, Zurich, Switzerland.
Neuroimage. 2008 May 15;41(1):153-68. doi: 10.1016/j.neuroimage.2008.02.012. Epub 2008 Mar 10.
Developmental dyslexia is a specific disorder of reading acquisition characterized by a phonological core deficit. Sentence reading is also impaired in dyslexic readers, but whether semantic processing deficits contribute is unclear. Combining spatially and temporally sensitive neuroimaging techniques to focus on semantic processing can provide a more comprehensive characterization of sentence reading in dyslexia. We recorded brain activity from 52 children (16 with dyslexia, 31 controls) with functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) in two separate counterbalanced sessions. The children silently read and occasionally judged simple sentences with semantically congruous or incongruous endings. fMRI and ERP activation during sentence reading and semantic processing was analyzed across all children and also by comparing children with dyslexia to controls. For sentence reading, we analyzed the response to all words in a sentence; for semantic processing, we contrasted responses to incongruous and congruous endings. Sentence reading was characterized by activation in a left-lateralized language network. Semantic processing was characterized by activation in left-hemispheric regions of the inferior frontal and superior temporal cortex and by an electrophysiological N400 effect after 240 ms with consistent left anterior source localization. Children with dyslexia showed decreased activation for sentence reading in inferior parietal and frontal regions, and for semantic processing in inferior parietal regions, and during the N400 effect. Together, this suggests that semantic impairment during sentence reading reduces dyslexic children's response in left anterior brain regions underlying the more phasic N400 effect and subsequently modulates the more sustained BOLD response in left inferior parietal regions.
发育性阅读障碍是一种以语音核心缺陷为特征的特定阅读习得障碍。阅读障碍读者的句子阅读也受损，但语义加工缺陷是否起作用尚不清楚。结合空间和时间敏感的神经成像技术来关注语义加工，可以更全面地描述阅读障碍中的句子阅读情况。我们在两个单独的平衡实验中，使用功能磁共振成像（fMRI）和事件相关电位（ERP）记录了52名儿童（16名阅读障碍儿童，31名对照儿童）的大脑活动。这些儿童默读并偶尔判断简单句子，句子结尾在语义上是一致或不一致的。我们分析了所有儿童在句子阅读和语义加工过程中的fMRI和ERP激活情况，也通过比较阅读障碍儿童和对照儿童进行了分析。对于句子阅读，我们分析了对句子中所有单词的反应；对于语义加工，我们对比了对不一致和一致结尾的反应。句子阅读的特征是左侧化语言网络的激活。语义加工的特征是额下回和颞上回左半球区域的激活，以及240毫秒后出现的电生理N400效应，且左侧前部源定位一致。阅读障碍儿童在句子阅读时，顶下小叶和额叶区域的激活减少，在语义加工时，顶下小叶区域的激活减少，在N400效应期间也是如此。总之，这表明句子阅读过程中的语义损伤会降低阅读障碍儿童在更具阶段性的N400效应基础上左前脑区域的反应，并随后调节左顶下小叶区域更持续的血氧水平依赖（BOLD）反应。
