Abstract：
The neural underpinnings of processing concrete and abstract semantics remain poorly understood. Previous fMRI studies have shown that multimodal and amodal neural networks respond differentially to different semantic types; importantly, abstract semantics activates more left-lateralized networks, as opposed to more bilateral activity for concrete words. Due to the lack of temporal resolution, these fMRI results do not allow to easily separate language- and task-specific brain responses and to disentangle early processing stages from later post-comprehension phenomena. To tackle this, we used magnetoencephalography (MEG), a time-resolved neuroimaging technique, in combination with a task-free oddball mismatch negativity (MMN) paradigm, an established approach to tracking early automatic activation of word-specific memory traces in the brain. We recorded the magnetic MMN responses in 30 healthy adults to auditorily presented abstract and concrete action verbs to assess lateralization of word-specific lexico-semantic processing in a set of neocortical areas. We found that MMN responses to these stimuli showed different lateralization patterns of activity in the upper limb motor area (BA4) and parts of Broca\'s area (BA45/BA47) within ∼100-350 ms after the word disambiguation point. Importantly, the greater leftward response lateralization for abstract semantics was due to the lesser involvement of the right-hemispheric homologues, not increased left-hemispheric activity. These findings suggest differential region-specific involvement of bilateral sensorimotor systems already in the early automatic stages of processing abstract and concrete action semantics.
摘要：
处理具体和抽象语义的神经基础仍然知之甚少。以前的功能磁共振成像研究表明，多模态和Amodal神经网络对不同的语义类型有不同的反应；重要的是，抽象语义激活了更多的左翼网络，而不是更多的双边活动来表达具体的话语。由于缺乏时间分辨率，这些功能磁共振成像结果不允许容易地将语言和任务特定的大脑反应分开,也不允许将早期处理阶段与后来的理解后现象分开.为了解决这个问题，我们使用了脑磁图(MEG)，时间分辨神经成像技术,结合无任务的怪球失配否定(MMN)范式，一种既定的方法来跟踪大脑中特定单词记忆痕迹的早期自动激活。我们记录了30名健康成年人对听觉上呈现的抽象和具体动作动词的磁MMN反应，以评估一组新皮层区域中特定单词的词汇语义处理的偏侧化。我们发现，MMN对这些刺激的反应在单词消歧点后的100-350毫秒内，在上肢运动区域（BA4）和Broca区域（BA45/BA47）的部分活动显示出不同的偏侧化模式。重要的是,抽象语义的更大的向左反应偏侧化是由于右半球同源物的参与较少，不增加左半球的活动。这些发现表明，双侧感觉运动系统已经处于处理抽象和具体动作语义的早期自动阶段，具有不同区域特定的参与。
