Department of Neurology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Cereb Cortex. 2010 Aug;20(8):1799-815. doi: 10.1093/cercor/bhp245. Epub 2009 Nov 17.
Reading aloud involves computing the sound of a word from its visual form. This may be accomplished 1) by direct associations between spellings and phonology and 2) by computation from orthography to meaning to phonology. These components have been studied in behavioral experiments examining lexical properties such as word frequency; length in letters or phonemes; spelling-sound consistency; semantic factors such as imageability, measures of orthographic, or phonological complexity; and others. Effects of these lexical properties on specific neural systems, however, are poorly understood, partially because high intercorrelations among lexical factors make it difficult to determine if they have independent effects. We addressed this problem by decorrelating several important lexical properties through careful stimulus selection. Functional magnetic resonance imaging data revealed distributed neural systems for mapping orthography directly to phonology, involving left supramarginal, posterior middle temporal, and fusiform gyri. Distinct from these were areas reflecting semantic processing, including left middle temporal gyrus/inferior-temporal sulcus, bilateral angular gyrus, and precuneus/posterior cingulate. Left inferior frontal regions generally showed increased activation with greater task load, suggesting a more general role in attention, working memory, and executive processes. These data offer the first clear evidence, in a single study, for the separate neural correlates of orthography-phonology mapping and semantic access during reading aloud.
朗读涉及从视觉形式计算单词的发音。这可以通过拼写和音系之间的直接联系来实现 1)，也可以通过从正字法到意义到音系的计算来实现 2)。这些组成部分已经在行为实验中进行了研究，这些实验检查了词汇属性，例如单词频率；字母或音素长度；拼写发音一致性；语义因素，如可形象化程度、正字法或音系复杂性的度量；以及其他因素。然而，这些词汇属性对特定神经系统的影响知之甚少，部分原因是词汇因素之间的高度相关性使得难以确定它们是否具有独立的影响。我们通过仔细选择刺激物来解相关联几个重要的词汇属性来解决这个问题。功能性磁共振成像数据显示了直接将正字法映射到音系的分布式神经系统，涉及左缘上回、后中颞叶和梭状回。与这些不同的是反映语义处理的区域，包括左中颞叶/下颞回、双侧角回和楔前叶/后扣带。左侧额下回区域通常随着任务负荷的增加而显示出更高的激活，这表明在注意力、工作记忆和执行过程中具有更一般的作用。这些数据在一项单独的研究中首次提供了清晰的证据，证明了在朗读过程中，正字法-音系映射和语义访问的独立神经关联。
