Abstract
One of the most important roles of vision is to provide information about the actions, intentions and identities of other individuals and so to enable successful interactions in a social environment. Critical regions in the human brain for perceiving others have been shown to include (but are not limited to) the posterior fusiform gyrus (Kanwisher et al., 1997; Peelen & Downing, 2005) and the posterior inferior temporal sulcus (Downing et al., 2001). This fMRI study examines the response in these cortical regions to biological motion using point-light walkers. We show that functionally defined body- and face-selective areas in posterior fusiform gyrus, and body- and motion-selective areas in inferior temporal sulcus all respond significantly to “point-light” human motion. We then apply voxel-by-voxel analyses of the response patterns to different stimuli in order to disentangle body-selective from face- and motion-selective responses in our regions of interest. Our analysis shows that, on a voxel-by-voxel basis, only body selectivity is correlated with biological motion selectivity. Biological motion selectivity is not related to motion or face selectivity. We conclude that: i) biological motion, through the process of structure-from-motion, engages areas involved in the analysis of the static human form; ii) body-selective regions in posterior fusiform gyrus and in posterior inferior temporal sulcus overlap with, but are distinct from, face- and motion-selective regions; iii) the interpretation of region-of-interest findings may be substantially altered when multiple patterns of selectivity are considered in parallel.