Abstract
Previous neuroimaging studies have shown that the posterior superior temporal sulcus (pSTS) is involved in processing changeable aspects of faces, such as expression and gaze direction. To be socially meaningful, however, such changes must be tracked across an individual. We therefore investigated the sensitivity of pSTS to facial identity while processing changeable characteristics of faces. We used fMRI to assess the neural responses in a large number of participants (N=103) viewing sequences of faces that varied in expression and viewpoint. There were two conditions: (1) same identity faces and (2) different identity faces. A whole-brain, group analysis revealed that the face-selective pSTS was more highly activated by same identity compared with different identity faces. In contrast, the face-selective fusiform face area (FFA) was activated more strongly by different identity than same identity faces. Because pSTS is not usually thought to encode facial identity, we sought to understand how the activation of the pSTS to changes in expression and viewpoint could be greater when faces have the same identity than when faces have different identities. We therefore measured how functional connectivity between core face-selective regions (OFA (occipital face area), FFA and pSTS) was affected by identity. We found a significant increase in the correlation of the residual time-courses between pSTS and OFA and between pSTS and FFA when participants viewed changeable aspects of same identity faces compared to different identity faces. There was no difference, however, in the functional connectivity between OFA and FFA when same or different identity faces were viewed. The identity-dependent change in connectivity between pSTS and other face-selective regions suggests that pSTS receives information about identity from these other regions, allowing it to process changeable features of the face in a socially meaningful way.
Meeting abstract presented at VSS 2012