Movements of the face play an important role in social communication. However, it is not clear whether there are distinct neural representations for different types of facial movement. In this study, we used fMRI to investigate the neural representations underlying changes caused by rigid and non-rigid movements of the face. In the first experiment, participants (n=83) viewed sequences of faces that varied in either facial expression (non-rigid change) or viewpoint (rigid change). Each sequence of images could be from the same identity or could contain different identities. Patterns of response were restricted to face-selective regions that were defined by the contrast face > scrambled face. Using correlation based MVPA, we found distinct patterns of response for facial expression and viewpoint within face-selective regions. A regression analysis showed that the patterns of response to expression and viewpoint were largely invariant to changes in facial identity and were consistent across participants. In the second experiment, we used an fMRI-adaptation paradigm to explore further the patterns of response to facial expression and viewpoint. Participants (n=31) viewed sequences of faces in which both expression and viewpoint were varied. We found adaptation to expression (lower responses in conditions when expression was unchanged) and adaptation to viewpoint (lower responses in conditions when viewpoint was unchanged) occurred in largely non-overlapping regions of the face-selective network. Together, these results reveal distinct topographic patterns of response for rigid and non-rigid movements in face-selective regions of the human brain. The segregation of regions involved in neural responses to changeable aspects of faces fits with the distinct social information that is conveyed by these different movements.
Meeting abstract presented at VSS 2014