Han Zaizhu, Ma Yujun, Gong Gaolang, Huang Ruiwang, Song Luping, Bi Yanchao
State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, 100875, China.
Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing, 100875, China.
Brain Struct Funct. 2016 Jan;221(1):577-89. doi: 10.1007/s00429-014-0926-2. Epub 2014 Oct 31.
In speech production, an important step before motor programming is the retrieval and encoding of the phonological elements of target words. It has been proposed that phonological encoding is supported by multiple regions in the left frontal, temporal and parietal regions and their underlying white matter, especially the left arcuate fasciculus (AF) or superior longitudinal fasciculus (SLF). It is unclear, however, whether the effects of AF/SLF are indeed related to phonological encoding for output and whether there are other white matter tracts that also contribute to this process. We comprehensively investigated the anatomical connectivity supporting phonological encoding in production by studying the relationship between the integrity of all major white matter tracts across the entire brain and phonological encoding deficits in a group of 69 patients with brain damage. The integrity of each white matter tract was measured both by the percentage of damaged voxels (structural imaging) and the mean fractional anisotropy value (diffusion tensor imaging). The phonological encoding deficits were assessed by various measures in two oral production tasks that involve phonological encoding: the percentage of nonword (phonological) errors in oral picture naming and the accuracy of word reading aloud with word comprehension ability regressed out. We found that the integrity of the left SLF in both the structural and diffusion tensor imaging measures consistently predicted the severity of phonological encoding impairment in the two phonological production tasks. Such effects of the left SLF on phonological production remained significant when a range of potential confounding factors were considered through partial correlation, including total lesion volume, demographic factors, lesions on phonological-relevant grey matter regions, or effects originating from the phonological perception or semantic processes. Our results therefore conclusively demonstrate the central role of the left SLF in phonological encoding in speech production.
在言语产生过程中，运动编程之前的一个重要步骤是目标词语音元素的检索和编码。有人提出，语音编码由左额叶、颞叶和顶叶区域及其深层白质中的多个区域支持，尤其是左弓状束（AF）或上纵束（SLF）。然而，尚不清楚AF/SLF的作用是否确实与输出的语音编码有关，以及是否有其他白质束也参与这一过程。我们通过研究一组69名脑损伤患者全脑所有主要白质束的完整性与语音编码缺陷之间的关系，全面调查了支持言语产生中语音编码的解剖连接性。每个白质束的完整性通过受损体素百分比（结构成像）和平均分数各向异性值（扩散张量成像）来测量。语音编码缺陷通过涉及语音编码的两项口语产生任务中的各种测量方法进行评估：口语图片命名中非词（语音）错误的百分比，以及在排除单词理解能力影响后大声朗读单词的准确性。我们发现，在结构成像和扩散张量成像测量中，左SLF的完整性始终能够预测两项语音产生任务中语音编码损伤的严重程度。当通过偏相关考虑一系列潜在混杂因素时，包括总病变体积、人口统计学因素、语音相关灰质区域的病变，或源自语音感知或语义过程的影响，左SLF对语音产生的这种影响仍然显著。因此，我们的结果确凿地证明了左SLF在言语产生的语音编码中的核心作用。
