Evidence for a specific cross-modal association deficit in dyslexia: an electrophysiological study of letter speech sound processing
Evidence for a specific cross-modal association deficit in dyslexia: an electrophysiological study of letter speech sound processing
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DOI：
10.1111/j.1467-7687.2010.01007.x
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发表时间：
2011-07-01
影响因子：
3.7
通讯作者：
Blomert, Leo
中科院分区：
文献类型：
--
作者：
Froyen, Dries;Willems, Gonny;Blomert, Leo
阅读障碍的音位缺陷理论认为，语音表征的退化可能会阻碍学习阅读所必需的稳定的字母语音联想的获得。然而，对于这种假定的字母语音关联问题，目前只有很少且主要是间接的证据。本研究旨在通过分析11岁阅读障碍儿童对孤立语音或与字母同时呈现或在语音前200ms呈现的事件相关电位(ERP)，来阐明字母语音联想问题在阅读障碍中的性质和作用。最近对正常读者的研究表明，字母在早期(失配性否定或MMN)和晚期(晚期歧视性否定或LDN)时间窗中系统地调节语音加工。当语音被字母呈现时，MMN和LDN对语音的幅度被增强。然而，即使经过4年的阅读教学，本研究中的阅读困难读者也没有表现出任何字母对语音的早期影响，这表明字母和语音没有自动整合。有趣的是，他们揭示了字母对语音处理的系统性后期效应，可能反映了字母和语音的简单联系。这种模式与在年龄匹配的正常读者中观察到的明显不同，后者既表现出早期效应，也表现出晚期效应，但让人想起在之前的一项研究中在初学者正常读者中观察到的结果(Froyen，Bonte，van Atteveldt&Blomert，2009)。字母语音的语音处理质量与阅读流利性直接相关，这一发现促使人们进一步研究视听整合在阅读障碍阅读失败发展中的作用。
The phonological deficit theory of dyslexia assumes that degraded speech sound representations might hamper the acquisition of stable letter speech sound associations necessary for learning to read. However; there is only scarce and mainly indirect evidence for this assumed letter speech sound association problem. The present study aimed at clarifying the nature and the role of letter speech sound association problems in dyslexia by analysing event-related potentials (ERP) of 11-year-old dyslexic children to speech sounds in isolation or combined with letters, which were presented either simultaneously with or 200 ms before the speech sounds. Recent studies with normal readers revealed that letters systematically modulated speech sound processing in an early (mismatch negativity or MMN) and late (Late Discriminatory Negativity or LDN) time-window The amplitude of the MMN and LDN to speech sounds was enhanced when speech sounds were presented with letters. The dyslexic readers in the present study, however, did not exhibit any early influences of letters on speech sounds even after 4 years of reading instruction, indicating no automatic integration of letters and speech sounds. Interestingly, they revealed a systematic late effect of letters on speech sound processing, probably reflecting the mere association of letters and speech sounds. This pattern is strongly divergent from that observed in age-matched normal readers, who showed both early and late effects, but reminiscent of that observed in beginner normal readers in a previous study (Froyen, Bonte, van Atteveldt & Blomert, 2009). The finding that the quality of letter speech sound processing is directly related to reading fluency urges further research into the role of audiovisual integration in the development of reading failure in dyslexia.