Abstract:

There is mixed evidence concerning the processing of word meaning. Early research into language assumed that word meaning was processed in the left temporal lobe. However, more recent research suggests that words are processed by distributed neuronal assemblies. This fMRI study explores embodied semantic processing and semantic system of Chinese action idioms. In the study, thirteen participants were asked to read one hundred and twenty four-character Chinese idioms, which are related to hand, face, mouth and feet action. Next, the participants were asked to judge whether the idiom’s meaning was related to mouth pronunciation. Functional brain imaging was conducted on a Siemens 3.0T scanner while participants performed Go/No go semantic judgment tasks. Imaging data were processed by spm8 software. Multi-comparison tests were conducted between the scores of the semantic comprehension task under four conditions (hand idioms, face idioms, mouth idioms and feet idioms). The activation was corrected by AlphaSim at the threshold of p<0.001 and cluster size > 39. The brain systems which are engaged in the processing of action idioms related to body parts were tested and Marsbar software was used to create images of the relevant areas of the cortex. The result showed: (1) when comparing activations for face and mouth idioms with activations for hand and feet idioms, more activations were observed for face and mouth idioms in the bilateral parietal lobe, precentral gyrus, postcentral gyrus, the dorsal premotor of the middle frontal gyrus and superior frontal gyrus, and inferior temporal gyrus; hand idioms caused more activation in the posterior of inferior parietal lobe bilaterally, inferior frontal gyrus in anterior part of premotor cortex, and middle frontal gyrus and in the dorsal of the premotor cortex; more activations were observed for feet idioms compared to hand idioms in dorsal along the midline and superior parietal lobe. (2) There were more activations for face and mouth idioms in the bilateral occipital lobe, the left dorsal premotor of the middle frontal gyrus and superior frontal gyrus, the pars triangularis in the inferior frontal gyrus and BA47, and in the left lingual gyrus when compared to hand and feet idioms. Superior frontal and middle frontal region of BA8 are activated to a greater extent for face idioms as opposed to mouth idioms. Mouth idioms specifically activated the left Broca and BA47. (3) Chinese action idioms activated prefrontal cortex, parietal lobe, occipital lobe and temporal lobe. But some differences were observed in activation between these regions. More activation was observed in parietal lobe for hand and feet idioms than face and mouth idioms. Face and mouth idioms were found to generate more activation in the occipital cortex than hand and feet idioms. This finding confirmed that the prefrontal-parietal-temporal network is the constitution of semantic system. The embodied semantics theory, states that verb meaning is represented in the cortex within the same sensory motor circuitry which executes the action. The cortex activation induced by Chinese action idioms in frontal-parietal lobe engaged action execution, and this pattern is consistent with the hypothesis of embodied semantics comprehension theory which indicates that semantic representation on imageable verbs is correlated with the somatotopic activation of motor and premotor cortex. The results demonstrate that semantic comprehension of Chinese action idioms is affected by our experience.

Key words: embodied cognition, Chinese action idioms, semantic processing, mirror-neuron system