Humphries Colin, Binder Jeffrey R, Medler David A, Liebenthal Einat
Department of Neurology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Neuroimage. 2007 Jul 1;36(3):924-32. doi: 10.1016/j.neuroimage.2007.03.059. Epub 2007 Apr 10.
The ability to create new meanings from combinations of words is one important function of the language system. We investigated the neural correlates of combinatorial semantic processing using fMRI. During scanning, participants performed a rating task on auditory word or pseudoword strings that differed in the presence of combinatorial and word-level semantic information. Stimuli included normal sentences comprised of thematically related words that could be readily combined to produce a more complex meaning, semantically incongruent sentences in which content words were randomly replaced with other content words, pseudoword sentences, and versions of these three sentence types in which syntactic structure was removed by randomly re-ordering the words. Several regions showed greater BOLD signal for stimuli with words than for those with pseudowords, including the left angular gyrus, left superior temporal sulcus, and left inferior frontal gyrus, suggesting that these areas are involved in semantic access at the single word level. In the angular and inferior frontal gyri these differences emerged early in the course of the hemodynamic response. An effect of combinatorial semantic structure was observed in the left angular gyrus and left lateral temporal lobe, which showed greater activation for normal compared to semantically incongruent sentences. These effects appeared later in the time course of the hemodynamic response, beginning after the entire stimulus had been presented. The data indicate a complex spatiotemporal pattern of activity associated with computation of word and sentence-level semantic information, and suggest a particular role for the left angular gyrus in processing overall sentence meaning.
通过词语组合创造新意义的能力是语言系统的一项重要功能。我们使用功能磁共振成像（fMRI）研究了组合语义加工的神经关联。在扫描过程中，参与者对听觉单词或伪单词串执行评分任务，这些单词或伪单词串在组合和单词层面的语义信息方面存在差异。刺激包括由主题相关的单词组成的正常句子，这些单词可以很容易地组合起来产生更复杂的意义；语义不一致的句子，其中实词被随机替换为其他实词；伪单词句子；以及这三种句子类型的变体，其中通过随机重新排列单词来去除句法结构。与伪单词刺激相比，几个区域对单词刺激显示出更大的血氧水平依赖（BOLD）信号，包括左侧角回、左侧颞上沟和左侧额下回，这表明这些区域参与单个单词层面的语义提取。在角回和额下回，这些差异在血液动力学反应过程中早期出现。在左侧角回和左侧颞叶外侧观察到了组合语义结构的效应，与语义不一致的句子相比，正常句子在这些区域显示出更强的激活。这些效应在血液动力学反应的时间进程中出现得较晚，在整个刺激呈现之后开始。数据表明与单词和句子层面语义信息计算相关的复杂时空活动模式，并表明左侧角回在处理整体句子意义方面具有特殊作用。
