Dole Marjorie, Meunier Fanny, Hoen Michel
Université Grenoble Alpes, LPNC, Grenoble, France; CNRS, LPNC, Grenoble, France.
L2C2, CNRS UMR 5304, Institut des Sciences Cognitives, Bron, France; Université de Lyon, F-69000 Lyon, France.
Neuropsychologia. 2014 Jul;60:103-14. doi: 10.1016/j.neuropsychologia.2014.05.016. Epub 2014 Jun 4.
Dyslexia is a language-based neurodevelopmental disorder. It is characterized as a persistent deficit in reading and spelling. These difficulties have been shown to result from an underlying impairment of the phonological component of language, possibly also affecting speech perception. Although there is little evidence for such a deficit under optimal, quiet listening conditions, speech perception difficulties in adults with dyslexia are often reported under more challenging conditions, such as when speech is masked by noise. Previous studies have shown that these difficulties are more pronounced when the background noise is speech and when little spatial information is available to facilitate differentiation between target and background sound sources. In this study, we investigated the neuroimaging correlates of speech-in-speech perception in typical readers and participants with dyslexia, focusing on the effects of different listening configurations. Fourteen adults with dyslexia and 14 matched typical readers performed a subjective intelligibility rating test with single words presented against concurrent speech during functional magnetic resonance imaging (fMRI) scanning. Target words were always presented with a four-talker background in one of three listening configurations: Dichotic, Binaural or Monaural. The results showed that in the Monaural configuration, in which no spatial information was available and energetic masking was maximal, intelligibility was severely decreased in all participants, and this effect was particularly strong in participants with dyslexia. Functional imaging revealed that in this configuration, participants partially compensate for their poorer listening abilities by recruiting several areas in the cerebral networks engaged in speech perception. In the Binaural configuration, participants with dyslexia achieved the same performance level as typical readers, suggesting that they were able to use spatial information when available. This result was, however, associated with increased activation in the right superior temporal gyrus, suggesting the need to reallocate neural resources to overcome speech-in-speech difficulties. Taken together, these results provide further understanding of the speech-in-speech perception deficit observed in dyslexia.
阅读障碍是一种基于语言的神经发育障碍。其特征是阅读和拼写方面存在持续的缺陷。这些困难已被证明是由语言音韵成分的潜在损伤导致的，可能还会影响言语感知。尽管在最佳、安静的聆听条件下几乎没有证据表明存在这种缺陷，但阅读障碍成年人的言语感知困难在更具挑战性的条件下经常被报道，比如当言语被噪音掩盖时。先前的研究表明，当背景噪音是言语且几乎没有空间信息可用于促进区分目标声源和背景声源时，这些困难会更加明显。在本研究中，我们调查了典型阅读者和阅读障碍参与者在言语中言语感知的神经影像学相关性，重点关注不同聆听配置的影响。14名患有阅读障碍的成年人和14名匹配的典型阅读者在功能磁共振成像（fMRI）扫描期间，对在同时出现的言语背景下呈现的单个单词进行了主观可懂度评分测试。目标单词总是在三种聆听配置之一中与四说话者背景一起呈现：双耳分听、双耳或单耳。结果表明，在单耳配置中，没有空间信息且能量掩蔽最大，所有参与者的可懂度都严重下降，并且这种影响在阅读障碍参与者中尤为强烈。功能成像显示，在这种配置下，参与者通过调动参与言语感知的脑网络中的几个区域来部分补偿他们较差的聆听能力。在双耳配置中，阅读障碍参与者达到了与典型阅读者相同的表现水平，这表明他们在有可用空间信息时能够利用它。然而，这一结果与右侧颞上回激活增加有关，这表明需要重新分配神经资源以克服言语中言语的困难。综上所述，这些结果进一步加深了我们对阅读障碍中观察到的言语中言语感知缺陷的理解。
