Abstract
The ability to recognize familiar faces across different viewing conditions contrasts with the inherent difficulty in the perception of unfamiliar faces across similar image manipulations. It is believed that this difference is based on the neural representation for familiar faces being less sensitive to changes in the image than it is for unfamiliar faces. Here, we used a fMR-adaptation paradigm to investigate neural correlates of familiar face recognition in face-selective regions of the human brain. 80 participants viewed faces presented in a blocked design. Each block contained different face images from either the same identity or different identities. Faces in each block were either familiar or unfamiliar to the participants. First, we defined face-selective regions by comparing the response to faces with the response to scrambled faces. This revealed the core face-selective regions (fusiform face area (FFA), occipital face area (OFA) and superior temporal face area (STS)), along with regions of the amygdala, hippocampus, middle temporal gyrus (MTG), precuneus and medial frontal gyrus (MFG). Next, we asked whether any of these regions responded more to familiar faces compared to unfamiliar faces. Higher responses to familiar faces were evident in the FFA, hippocampus, MTG, precuneus and MFG. No face-selective regions responded more to unfamiliar compared to familiar faces. Finally, we tested whether any of these regions showed image invariant adaptation to faces. We found a higher response to different identity compared to same identity familiar faces (adaptation) in the hippocampus. However, there was no adaptation to unfamiliar faces. These findings are consistent with electrophysiological studies that have found identity-invariant neuronal responses in the medial temporal lobe (Quiroga et al., 2005, Nature, 435: 1102-1107). Taken together, our results suggest that the marked differences in the perception of familiar and unfamiliar faces may depend critically on neural representations in the medial temporal lobe.
Meeting abstract presented at VSS 2015