The role of motor processes in egocentric mental transformations involving nonbody stimuli

Previous research has shown that response measures, which instill embodiment, such as pointing, serve to anchor participants to their physical body during imagined erspective mental rotations (Wraga, Flynn, and Evans; under review). The current study used functional magnetic resonance imaging (fMRI) to investigate if recruitment of the body schema using virtual pointers would activate low-level cortical motor areas of the brain across different types of mental rotation tasks. Participants viewed depictions of single three-dimensional Shepard–Metzler objects situated within a sphere and performed both imagined hand and viewer tasks using these stimuli. The participants used button presses serving as virtual pointers to make right/left responses for each task. Low-level cortical motor activation (M1) was found for both egocentric tasks, yet the location of this activation was found to differ along the motor strip. For the Hand task, the activation was more medial and roughly corresponded to the shoulder/arm region of the motor cortex map. For the Viewer task, the motor activation was more lateral and corresponded roughly to the face and head region of the motor cortex map. These results are discussed relative to recent hypotheses regarding the role of body schema in imagined egocentric transformations, as well as in the context of important visual, spatial, and motor processes