Simos P G, Basile L F, Papanicolaou A C
Department of Neurosurgery, University of Texas, Houston Health Science Center, 77030, USA.
Brain Res. 1997 Jul 11;762(1-2):29-39. doi: 10.1016/s0006-8993(97)00349-1.
The aim of the present investigation was to localize the sources of the N400 response elicited in a sentence-reading paradigm. Eight neurologically healthy adults viewed sentences that were presented one word at a time in the center of a computer screen. Half of the sentences ended with a semantically inappropriate word, while the other half had appropriate endings. Event-related potentials recorded at Fz and Pz showed a negative-going deflection, the amplitude of which was strongly affected by semantic congruity (N400). Evoked magnetic fields that were simultaneously recorded over the left hemisphere showed clear magnetic field extrema in seven subjects during the time course of the N400. Underlying sources were successfully modeled as single equivalent current dipoles. Anatomical regions that contained the dipoles were localized by superimposing dipole coordinates onto magnetic resonance scans. Dipole regions were found in temporal lobe structures, in the vicinity of the hippocampus and the parahippocampal gyrus (in two subjects) and in posterior temporal neocortical regions (in the vicinity of the middle temporal gyrus; in five subjects). These findings are consistent with the view that posterior association cortices in the left hemisphere are involved in word recognition and semantic comprehension during reading.
本研究的目的是定位在句子阅读范式中引发N400反应的来源。八名神经健康的成年人观看在电脑屏幕中央一次呈现一个单词的句子。一半的句子以语义不恰当的单词结尾，而另一半有恰当的结尾。在Fz和Pz记录的事件相关电位显示出一个负向偏转，其幅度受到语义一致性的强烈影响（N400）。在左半球同时记录的诱发磁场在N400的时间进程中，七名受试者显示出明显的磁场极值。潜在来源成功地被建模为单个等效电流偶极子。通过将偶极子坐标叠加到磁共振扫描上来定位包含偶极子的解剖区域。在颞叶结构中发现偶极子区域，在海马体和海马旁回附近（两名受试者）以及颞叶后部新皮质区域（在颞中回附近；五名受试者）。这些发现与左半球后部联合皮质参与阅读过程中的单词识别和语义理解的观点一致。
