"How to do things with words": role of motor cortex in semantic representation of action words

Language, believed to have originated from actions, not only functions as a medium to access other minds, but it also helps us commit actions and enriches our social life. This fMRI study investigated the semantic and neural representations of actions and mental states. We focused mainly on language semantics (comprehending sentences with action words versus those with mental state words). While in an fMRI scanner, twenty-four healthy, right-handed adult volunteers read a series of sentences with a verb depicting either a mental state (e.g., deceive, persuade) or an action (e.g., punch, kick), and answered a comprehension question that followed. Overall, this task showed brain activation in the left inferior frontal gyrus and in the left posterior superior temporal sulci. While comprehending sentences with mental state terms, participants showed greater activation in left orbitofrontal, and in left precuneus areas. On the other hand, the action sentences recruited more primary motor, left inferior parietal, bilateral occipital, right superior temporal, and right inferior frontal areas. The findings of this study underscore the role of motor and visuospatial involvement in action word representation in the human brain.