Involvement of the Motor System in Comprehension of Non-Literal Action Language: A Meta-Analysis Study

Although numerous studies have shown that the sensory-motor system is involved in semantic processing of language stimuli, it is still unclear whether comprehension of abstract concepts is embodied, and whether the involvement of the sensory-motor system is context-dependent. Investigation of how the motor system is activated during comprehension of non-literal action languages can help address these issues. So far several studies have reported brain activations during non-literal action language comprehension, but the findings are highly inconsistent because of different types of non-literal action language stimuli. To clarify how the motor system is involved in comprehension of different types of non-literal languages, the current study conducted quantitative meta-analyses on fMRI findings about comprehension of sentences describing fictive motions, metaphoric actions, and idiomatic actions. Results showed that fictive motion sentences elicited activation in the right parahippocampal gyrus, an area important for spatial processing. For metaphoric actions, the left precentral gyrus (BA 6) was strongly activated, suggesting a link between metaphoric and literal meanings. For idiomatic actions, activity was found in the left inferior frontal gyrus (BA 44/45), highlighting semantic selection and inhibition. No premotor or motor activity was found in idiom condition. These results together suggest that the involvement of the sensory-motor system in abstract concepts processing is flexible, depending on semantic features of the language stimuli and links between abstract and literal meanings.