Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo Tokyo, Japan ; Japan Society for the Promotion of Science Tokyo, Japan.
Front Hum Neurosci. 2013 Oct 22;7:681. doi: 10.3389/fnhum.2013.00681. eCollection 2013.
In both vocal and sign languages, we can distinguish word-, sentence-, and discourse-level integration in terms of hierarchical processes, which integrate various elements into another higher level of constructs. In the present study, we used magnetic resonance imaging and voxel-based morphometry (VBM) to test three language tasks in Japanese Sign Language (JSL): word-level (Word), sentence-level (Sent), and discourse-level (Disc) decision tasks. We analyzed cortical activity and gray matter (GM) volumes of Deaf signers, and clarified three major points. First, we found that the activated regions in the frontal language areas gradually expanded in the dorso-ventral axis, corresponding to a difference in linguistic units for the three tasks. Moreover, the activations in each region of the frontal language areas were incrementally modulated with the level of linguistic integration. These dual mechanisms of the frontal language areas may reflect a basic organization principle of hierarchically integrating linguistic information. Secondly, activations in the lateral premotor cortex and inferior frontal gyrus were left-lateralized. Direct comparisons among the language tasks exhibited more focal activation in these regions, suggesting their functional localization. Thirdly, we found significantly positive correlations between individual task performances and GM volumes in localized regions, even when the ages of acquisition (AOAs) of JSL and Japanese were factored out. More specifically, correlations with the performances of the Word and Sent tasks were found in the left precentral/postcentral gyrus and insula, respectively, while correlations with those of the Disc task were found in the left ventral inferior frontal gyrus and precuneus. The unification of functional and anatomical studies would thus be fruitful for understanding human language systems from the aspects of both universality and individuality.
在口语和手语中，我们可以根据分层过程区分词、句和语篇级别的整合，即将各种元素整合到另一个更高层次的结构中。在本研究中，我们使用磁共振成像和基于体素的形态测量学（VBM）测试了日本手语（JSL）中的三种语言任务：词级（Word）、句级（Sent）和语篇级（Disc）决策任务。我们分析了聋人手语者的皮质活动和灰质（GM）体积，并阐明了三个主要观点。首先，我们发现额语言区的激活区域在背腹轴上逐渐扩大，对应于三个任务的语言单位差异。此外，额语言区的每个区域的激活与语言整合水平呈递增调节。这些额语言区的双重机制可能反映了语言信息分层整合的基本组织原则。其次，外侧运动前皮质和下额回的激活呈左侧偏侧化。对语言任务的直接比较在这些区域显示出更集中的激活，表明它们的功能定位。第三，我们发现个体任务表现与局部区域的 GM 体积之间存在显著的正相关，即使考虑到 JSL 和日语的习得年龄（AOAs）也是如此。更具体地说，与 Word 和 Sent 任务的表现相关的区域分别在左侧中央后回和岛叶，而与 Disc 任务的表现相关的区域在左侧腹下额回和楔前叶。因此，功能和解剖学研究的统一对于从普遍性和个体性两个方面理解人类语言系统将是富有成效的。
