Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Pacheco de Melo 1860, C1126AAB, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Godoy Cruz 2290, C1425FQB, Buenos Aires, Argentina; Faculty of Education, National University of Cuyo (UNCuyo), Sobremonte 74, M5500, Mendoza, Argentina.
Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Pacheco de Melo 1860, C1126AAB, Buenos Aires, Argentina; Fundación Escuela de Medicina Nuclear (FUESMEN) and Comisión Nacional de Energía Atómica (CNEA), Garibaldi 405, M5500, Mendoza, Argentina; Instituto Balseiro and Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo), Padre Jorge Contreras 1300, M5502 JMA, Mendoza, Argentina.
Neuroimage. 2019 Aug 15;197:439-449. doi: 10.1016/j.neuroimage.2019.05.002. Epub 2019 May 3.
Research on how the brain construes meaning during language use has prompted two conflicting accounts. According to the 'grounded view', word understanding involves quick reactivations of sensorimotor (embodied) experiences evoked by the stimuli, with simultaneous or later engagement of multimodal (conceptual) systems integrating information from various sensory streams. Contrariwise, for the 'symbolic view', this capacity depends crucially on multimodal operations, with embodied systems playing epiphenomenal roles after comprehension. To test these contradictory hypotheses, the present magnetoencephalography study assessed implicit semantic access to grammatically constrained action and non-action verbs (n = 100 per category) while measuring spatiotemporally precise signals from the primary motor cortex (M1, a core region subserving bodily movements) and the anterior temporal lobe (ATL, a putative multimodal semantic hub). Convergent evidence from sensor- and source-level analyses revealed that increased modulations for action verbs occurred earlier in M1 (∼130-190 ms) than in specific ATL hubs (∼250-410 ms). Moreover, machine-learning decoding showed that trial-by-trial classification peaks emerged faster in M1 (∼100-175 ms) than in the ATL (∼345-500 ms), with over 71% accuracy in both cases. Considering their latencies, these results challenge the 'symbolic view' and its implication that sensorimotor mechanisms play only secondary roles in semantic processing. Instead, our findings support the 'grounded view', showing that early semantic effects are critically driven by embodied reactivations and that these cannot be reduced to post-comprehension epiphenomena, even when words are individually classified. Briefly, our study offers non-trivial insights to constrain fine-grained models of language and understand how meaning unfolds in neural time.
关于大脑在语言使用过程中如何构建意义的研究提出了两种相互矛盾的观点。根据“扎根观点”，单词理解涉及对刺激物引起的感觉运动（具身）体验的快速再激活，同时或之后涉及多模态（概念）系统整合来自各种感觉流的信息。相反，对于“符号观点”，这种能力取决于多模态操作，具身系统在理解后起着副现象的作用。为了检验这些相互矛盾的假设，本项脑磁图研究评估了语法约束的动作动词和非动作动词的隐性语义访问（每类 100 个），同时测量来自初级运动皮层（M1，一个支持身体运动的核心区域）和前颞叶（ATL，一个假定的多模态语义中枢）的时空精确信号。来自传感器和源水平分析的综合证据表明，动作动词的调制增加发生在 M1 中较早（约 130-190ms），而不是在特定的 ATL 中枢（约 250-410ms）。此外，逐次分类解码显示，在 M1 中，分类峰出现得更快（约 100-175ms），而在 ATL 中则较慢（约 345-500ms），在两种情况下的准确率均超过 71%。考虑到它们的潜伏期，这些结果挑战了“符号观点”及其暗示，即感觉运动机制在语义处理中仅起次要作用。相反，我们的研究结果支持“扎根观点”，表明早期的语义效应是由具身再激活驱动的，这些效应不能简化为理解后的副现象，即使是在单个单词分类的情况下。简而言之，我们的研究为语言的精细模型提供了重要的见解，并帮助理解意义如何在神经时间中展开。
