fMRI Activation in Visual Processing and Memory Regions for Famous Versus Nonfamous Faces.

Abstract:
The effects of prior exposure to faces on the activity of various visual processing and memory regions were examined in two experiments using famous faces, nonfamous faces, scrambled faces, and noise patterns. Comparisons of faces, scrambled faces, and noise patterns permitted identification of cortical visual areas involved in face processing. It was then possible to determine which of these regions are differentially active for famous versus nonfamous faces. Medial occipital gyrus and fusiform gyrus were active (R>L) for scrambled faces compared to noise patterns. These same areas were active for faces compared to noise, but the area of activation expanded (compared to that for scrambled faces) to include more anterior regions of fusiform gyrus, similar to those reported in other studies of face processing. The spatial extent of activation in this fusiform area, was greater in the right hemisphere for famous compared to nonfamous faces, and in other portions of the ventral stream as well. Greater activation for famous compared to nonfamous faces was also seen in medial temporal-lobe regions, including hippocampus. These findings of greater activation for famous versus nonfamous faces contrast with various findings from priming studies in which decreases in cortical activation are observed for repeated versus novel stimuli.