关键词: 运动特征, 抽象动词, 具身认知, 任务态功能磁共振成像, 肌电图

Abstract: Embodied cognition theories assume that conceptual representations are essentially rooted in modal experiential information.Abstract concepts, however, which do not refer to entities with direct sensory-motor experience, have challenged the embodied theories. Taking verbs as an example, it is still debated whether abstract verbs meaning are represented in the sensorimotor system.After sorting out and analyzing the previous studies, it can be speculated that the involvement of the motor system in the representations of abstract verbs may be modulated by the motor features. Abstract verbs with more direct motor experiences acquired during their learning are more likely to be predominant in the motor features and accordingly grounded much more in the motor system. The present study aimed to explore the causal role of motor features of abstract verbs in their representations in the motor system and provide an explanation for the variance of previous results. Forty-four participants (6 males) were recruited in Experiment 1, one male participant withdrew for private reasons and all the data were removed from the analysis. Experiment 1 lasted four days. Day 1 and Day 4 were the pre-and post-learning test respectively, in which participants were instructed to perform a lexical decision task first inside a 3.0 T Siemens Prisma MRI scanner. During the scanning, 240 words (including 60 target novel words) were presented in a pseudorandomized sequence within an event-related design. Then, outside the scanner, the same behavioral task with 120 words (including 60 target novel words) were performed on computers (but responded in a way of the action-sentence compatibility paradigm). On Day 2 and 3, 60 target novel words and their interpretive abstract meanings, which were printed on the cards, were learned and memorized for about one hour each day. While learning participants had to perform a specific hand movement toward or away from themselves as required, with the aim to successfully increase the predominance of motor features in the target words. Acquired neuroimaging data of the pre-learning and the post-learning test were respectively pre-processed and analyzed using SPM and DPABI. On the whole brain level a 2×2 within analysis of variance (ANOVA) was performed. The two within-subject factors were testing phase (pre-vs. post-learning), and word type (learning vs. non-learning novel words). We found that comparing the processing of the leaning novel words, that is, the novel words with increased motor features, in the post- versus pre-learning test yielded stronger activations in motor-related brain areas (such as the left precentral gyrus). Furthermore, the scores on the motor features in the learning novel words significantly predicted the degree of neural activation in the motor system (i.e., the right pre- and post central gyrus, the left precentral gyrus, etc.) in the post-learning test. Thirty subjects from Experiment 1 participated in Experiment 2.They were instructed to learn 30 novel words selected from the above 60 target words in the similar way as in Experiment 1. After about 30-minute learning, the participants had to perform the lexical decision task while their arm’s electromyographic activities were recorded with a wireless EMG measurement module from BIOPAC. The results showed that processing of the learning novel words with increased motor features, compared to the non-learning novel words (i.e., the baseline), elicited an enhanced EMG activity of the right extensor digitorum muscle. In conclusion, the present study confirmed the causal role of motor features in the embodied representations (ie. representations in the motor system) of abstract verbs. The motor features’ increasing would make the representations of the abstract verbs more dependent on the motor system. Moreover, processing of abstract verbs with enough motor features could elicit motor resonance also in the peripheral motor system. These findings provide new evidence and important interpretation for the embodied cognition theories.

Key words: motor features, abstract verbs, embodiment, fMRI, EMG