The influence of complex action knowledge on representations of novel graspable objects: evidence from functional magnetic resonance imaging.

The influence of action knowledge associated with novel objects was investigated using functional magnetic resonance imaging. Participants were trained on complex actions associated with novel objects ("tools") and had experience manipulating other visually similar novel objects ("shapes"). During scanning, participants viewed, imagined grasping, and imagined using the objects. Based on previous neuroimaging and neuropsychological findings, our primary goal was to examine frontal and parietal regions subserving action representations associated with visual objects, namely the left inferior parietal lobule (IPL), the left ventral premotor cortex (VPM) and the presupplementary motor cortex (pre-SMA). We predicted differences between the tool and shape stimuli, modulated also by task demands. In viewing, we found greater effect sizes in the left VPM and IPL for tools versus shapes. In grasping, there was similar activation with both object types. The largest differences existed in using, in which greater effect sizes were found for tools versus shapes in left IPL and pre-SMA, and marginally in the left VPM. We suggest that representations of tools extend beyond classically defined affordances and recruit processing about both graspability and known action plans in tasks involving visual memory, motor imagery, and motor execution.