Body and Object Effectors: The Organization of Object Representations in High-Level Visual Cortex Reflects Body-Object Interactions

The principles driving the functional organization of object representations in high-level visual cortex are not yet fully understood. In four human fMRI experiments, we provide evidence that the organization of high-level visual cortex partly reflects the degree to which objects are typically controlled by the body to interact with the world, thereby extending the body's boundaries. Univariate whole-brain analysis showed an overlap between responses to body effectors (e. g., hands, feet, and limbs) and object effectors (e. g., hammers, combs, and tennis rackets) in lateral occipitotemporal cortex (LOTC) and parietal cortex. Region of interest analyses showed that a hand-selective region in left LOTC responded selectively to object effectors relative to a range of noneffector object control conditions (e. g., graspable objects, "act-on" objects, musical instruments). Object ratings showed that the strong response to object effectors in hand-selective LOTC was not due to general action-related object properties shared with these control conditions, such as hand priming, hand grasping, and hand-action centrality. Finally, whole-brain representational similarity analysis revealed that the similarity of multivoxel object response patterns in left lateral occipitotemporal cortex selectively predicted the degree to which objects were rated as being controlled by and extending the body. Together, these results reveal a clustering of body and object effector representations, indicating that the organization of object representations in high-level visual cortex partly reflects how objects relate to the body.