Brain activity for peripheral biological motion in the posterior superior temporal gyrus and the fusiform gyrus: Dependence on visual hemifield and view orientation

Biological motion, the movement of the human body presented by a small number of point lights, activates among other regions lining the posterior superior temporal sulcus (pSTS) and gyrus (pSTG) and of the fusiform gyrus. In previous studies with foveal stimuli the activity in the pSTS/pSTG was often confined to the right hemisphere and bilateral in fusiform gyrus. We presented biological motion stimuli in peripheral vision and measured the BOLD responses with functional MRI to test whether the right dominance in pSTS/pSTG also occurred with peripheral stimuli. We found activation exclusively in the right pSTG for both visual hemifields. In the fusiform gyrus activation was found in both hemispheres and for peripheral stimuli strongest for contralateral stimulation. However, in both fusiform gyri leftward-facing stimuli activated different subfields than rightward-facing stimuli, indicating a clustering of the selectivity for the orientation of the human body form. No such clustering was observed in the pSTG. The results indicate for the fusiform gyrus an organization with respect to the view orientation of the stimulus.