Romero Lauro Leonor J, Mattavelli Giulia, Papagno Costanza, Tettamanti Marco
Dipartimento di Psicologia, Università di Milano-Bicocca, Milano, Italy.
Neuroimage. 2013 Dec;83:361-71. doi: 10.1016/j.neuroimage.2013.06.050. Epub 2013 Jun 20.
The role of sensory-motor components in language processing is a central topic in cognitive neuroscience. Recent studies showed that the processing of action words recruits cortical motor regions involved in the planning and execution of the described actions. However, it remains unclear to what extent the abstract versus concrete nature of the described motion modulates the activation of premotor and motor areas and how the agent affects this modulation. Here, we contribute to this line of research by investigating the comprehension of motion verbs, used in a literal versus figurative context, in an fMRI study with normal subjects in which the somatotopy of activation was investigated by presenting motion verbs that involve upper vs. lower limbs. A set of sentences including a motion verb used in a literal, fictive (only lower limb), metaphorical, or idiomatic way was studied. Cognition verbs were also included as control. We found that figurative sentences compared to literal ones produced a greater activation of a bilateral fronto-temporal network, in line with previous studies. Moreover, fictive motion activated a more posterior region, involving primary visual areas and motion sensitive visual areas, but also the left middle frontal gyrus. Crucially, the left precentral gyrus was activated in the case of the upper limb for literal and metaphorical motion sentence types, but not idiomatic sentences. For fictive motion, we found a lower limb-related somatotopic effect, also present for literal sentences, while the evidence for metaphorical and idiomatic sentences was less strong. In conclusion, our results confirm that premotor areas are activated by language understanding, but to a different degree depending on the specific literal versus figurative context in which motion verbs appear. Therefore, they support weak embodied views suggesting that the motor system enhances the comprehension of linguistically encoded actions.
感觉运动成分在语言加工中的作用是认知神经科学的核心主题。最近的研究表明，动作词的加工会激活参与所描述动作计划和执行的皮层运动区域。然而，所描述动作的抽象与具体性质在多大程度上调节运动前区和运动区的激活，以及动作者如何影响这种调节，仍不清楚。在此，我们通过在一项功能磁共振成像（fMRI）研究中调查正常受试者对字面与比喻语境中使用的运动动词的理解，为这一研究方向做出贡献。在该研究中，通过呈现涉及上肢与下肢的运动动词来研究激活的躯体定位。研究了一组句子，其中的运动动词以字面、虚构（仅涉及下肢）、隐喻或习语的方式使用。还纳入了认知动词作为对照。我们发现，与字面句子相比，比喻句子会使双侧额颞网络产生更大的激活，这与先前的研究一致。此外，虚构运动激活了更靠后的区域，包括初级视觉区和运动敏感视觉区，以及左侧额中回。至关重要的是，对于上肢，左侧中央前回在字面和隐喻运动句子类型的情况下被激活，但在习语句子中未被激活。对于虚构运动，我们发现了与下肢相关的躯体定位效应，字面句子中也存在这种效应，而隐喻和习语句子的证据则不那么明显。总之，我们的结果证实运动前区会因语言理解而被激活，但激活程度因运动动词出现的具体字面与比喻语境而异。因此，它们支持弱具身观点，即运动系统增强对语言编码动作的理解。
