An Sora, Oh Se Jin, Jun Sang Beom, Sung Jee Eun
Department of Communication Disorders, Ewha Womans University, Seoul, South Korea.
Department of Electronic and Electrical Engineering, Ewha Womans University, Seoul, South Korea.
Front Aging Neurosci. 2022 Jun 10;14:877235. doi: 10.3389/fnagi.2022.877235. eCollection 2022.
Age-related differences in sentence-level lexical-semantic processes have been extensively studied, based on the N400 component of event-related potential (ERP). However, there is still a lack of understanding in this regard at the brain-region level. This study explores aging effects on sentence-level semantic processing by comparing the characteristics of the N400 ERP component and brain engagement patterns within individual N400 time windows for two age groups (16 younger adults aged 24.38 ± 3.88 years and 15 older adults aged 67.00 ± 5.04 years) during sentence processing with different plausibility conditions. Our results demonstrated that the N400 effect according to the plausibility condition occurred in different temporal windows in the two age groups, with a delay in the older group. Moreover, it was identified that there was a distinct difference between the groups in terms of the source location of the condition-dependent N400 effect even though no significant difference was derived in its magnitude itself at the sensor-level. Interestingly, the source analysis results indicated that the two groups involved different functional networks to resolve the same semantic violations: the younger group activated the regions corresponding to the typical lexical-semantic network more, whereas the older group recruited the regions belonging to the multiple-demand network more. The findings of this study could be used as a basis for understanding the aging brain in a linguistic context.
基于事件相关电位（ERP）的N400成分，人们对句子层面词汇语义加工中的年龄相关差异进行了广泛研究。然而，在脑区层面，这方面仍缺乏了解。本研究通过比较两个年龄组（16名年龄在24.38±3.88岁的年轻成年人和15名年龄在67.00±5.04岁的老年人）在不同合理性条件下句子加工过程中N400 ERP成分的特征以及个体N400时间窗内的大脑参与模式，探讨衰老对句子层面语义加工的影响。我们的结果表明，根据合理性条件产生的N400效应在两个年龄组的不同时间窗出现，老年组存在延迟。此外，研究发现，尽管在传感器层面条件依赖性N400效应的幅度本身没有显著差异，但两组在该效应的源位置方面存在明显差异。有趣的是，源分析结果表明，两组在解决相同语义违反问题时涉及不同的功能网络：年轻组更多地激活了与典型词汇语义网络相对应的区域，而老年组更多地招募了属于多重需求网络的区域。本研究结果可作为在语言背景下理解衰老大脑的基础。
