Luo Hao, Ni Jing-Tian, Li Zhi-Hao, Li Xiao-Ou, Zhang Da-Ren, Zeng Fan-Gang, Chen Lin
Auditory Research Laboratory, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China.
Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19558-63. doi: 10.1073/pnas.0607065104. Epub 2006 Dec 11.
In tonal languages such as Mandarin Chinese, a lexical tone carries semantic information and is preferentially processed in the left brain hemisphere of native speakers as revealed by the functional MRI or positron emission tomography studies, which likely measure the temporally aggregated neural events including those at an attentive stage of auditory processing. Here, we demonstrate that early auditory processing of a lexical tone at a preattentive stage is actually lateralized to the right hemisphere. We frequently presented to native Mandarin Chinese speakers a meaningful auditory word with a consonant-vowel structure and infrequently varied either its lexical tone or initial consonant using an odd-ball paradigm to create a contrast resulting in a change in word meaning. The lexical tone contrast evoked a stronger preattentive response, as revealed by whole-head electric recordings of the mismatch negativity, in the right hemisphere than in the left hemisphere, whereas the consonant contrast produced an opposite pattern. Given the distinct acoustic features between a lexical tone and a consonant, this opposite lateralization pattern suggests the dependence of hemisphere dominance mainly on acoustic cues before speech input is mapped into a semantic representation in the processing stream.
在诸如汉语普通话这样的声调语言中，词汇声调携带语义信息，并且如功能磁共振成像或正电子发射断层扫描研究所示，以母语者而言，词汇声调优先在左脑半球进行处理，这些研究可能测量了包括听觉处理注意阶段的神经事件在内的时间上聚合的神经活动。在此，我们证明，在注意前阶段对词汇声调的早期听觉处理实际上偏向于右脑半球。我们使用奇偶数范式，向汉语普通话母语者频繁呈现具有辅音-元音结构的有意义听觉单词，并偶尔改变其词汇声调或首辅音，以形成对比从而导致词义变化。如通过失配负波的全脑电记录所示，词汇声调对比在右脑半球引发的注意前反应比在左脑半球更强，而辅音对比则产生相反的模式。鉴于词汇声调与辅音之间存在明显的声学特征，这种相反的偏侧化模式表明，在语音输入在处理流中被映射为语义表征之前，半球优势主要依赖于声学线索。
