Does mental rotation emulate motor processes? An electrophysiological study of objects and body parts
Abstract Several arguments suggest that mental rotation (MR) and motor planning may share embodied neural mechanisms, but the overlap between cognitive processes recruited during MR of objects and body parts is not well established. We here used high-density EEG to examine the cognitive similarity between MR of non-manipulable objects (chairs) and bodily stimuli (hands). We selected chairs because they may appear in a recognizable left-right orientation and are not automatically associated with a manual action. Participants had identical response options for both types of stimuli, and they gave responses orally in order to prevent possible interference with motor imagery. MR of hands and chairs generated very similar behavioral responses, time-courses and neural sources of evoked-response potentials (ERPs). ERP segmentation analysis revealed distinct time windows during which differential effects of stimulus type and angular disparity were observed. An early period (90-160 ms) differentiated only between stimulus types, and was associated with occipito-temporal activity. A later period (290-330 ms) revealed strong effects of angular disparity, associated with electrical sources in the right angular gyrus and primary motor/somatosensory cortex. These data suggest that spatial transformation processes and motor planning are recruited simultaneously, supporting the involvement of motor emulation processes in MR.