Van Petten Cyma, Luka Barbara J
Department of Psychology, University of Arizona, Tucson, AZ 85721, USA.
Brain Lang. 2006 Jun;97(3):279-93. doi: 10.1016/j.bandl.2005.11.003. Epub 2005 Dec 15.
Measures of electrical brain activity (event-related potentials, ERPs) have been useful in understanding language processing for several decades. Extant data suggest that the amplitude of the N400 component of the ERP is a general index of the ease or difficulty of retrieving stored conceptual knowledge associated with a word, which is dependent on both the stored representation itself, and the retrieval cues provided by the preceding context. Recordings from patients with brain damage, intracranial recordings, and magnetoencephalographic data implicate a (probably large portion of) the left temporal lobe as the largest source of the N400 semantic context effect, with a substantial but lesser contribution from the right temporal lobe. Event-related functional magnetic resonance (fMRI) studies using semantic context manipulations are dominated by observations of greater hemodynamic activity for incongruent sentence completions or semantically unrelated words than congruent or related words, consistent with the direction of the ERP effect. The locations of the hemodynamic effects show some variability across studies, but one commonly identified region is the left superior temporal gyrus, which is compatible with the electrophysiological results. A second commonly identified region in the fMRI studies is the left inferior frontal gyrus, which does not appear to make a substantial contribution to the N400 effect.
几十年来，测量大脑电活动（事件相关电位，ERPs）在理解语言处理方面一直很有用。现有数据表明，ERP的N400成分的振幅是检索与一个单词相关的存储概念知识难易程度的一个通用指标，这既取决于存储表征本身，也取决于前文语境提供的检索线索。对脑损伤患者的记录、颅内记录以及脑磁图数据表明，左颞叶（可能是很大一部分）是N400语义语境效应的最大来源，右颞叶也有相当大但较小的贡献。使用语义语境操纵的事件相关功能磁共振成像（fMRI）研究主要观察到，与一致或相关单词相比，不一致的句子完成或语义无关的单词会有更大的血液动力学活动，这与ERP效应的方向一致。血液动力学效应的位置在不同研究中存在一些差异，但一个常见的确定区域是左颞上回，这与电生理结果相符。fMRI研究中另一个常见的确定区域是左额下回，它似乎对N400效应没有实质性贡献。
