Abstract
This fMRI study investigates the neural mechanisms supporting the retrieval of action semantics. A novel motor imagery task was used in which participants were required to imagine planning actions with a familiar object (e.g. a toothbrush) or with an unfamiliar object (e.g. a pair of pliers) based on either goal-related information (i.e. where to move the object) or grip-related information (i.e. how to grasp the object). Planning actions with unfamiliar compared to familiar objects was slower and was associated with increased activation in the bilateral superior parietal lobe, the right inferior parietal lobe and the right insula. The stronger activation in parietal areas for unfamiliar objects fits well with the idea that parietal areas are involved in motor imagery and suggests that this process takes more effort in the case of novel or unfamiliar actions. In contrast, the planning of familiar actions resulted in increased activation in the anterior prefrontal cortex, suggesting that subjects maintained a stronger goal-representation when planning actions with familiar compared to unfamiliar objects. These findings provide further insight into the neural structures that support action semantic knowledge for the functional use of real-world objects and suggest that action semantic knowledge is activated most readily when actions are planned in a goal-directed manner.
