Face processing in the chimpanzee brain.

Human face recognition involves highly specialized cognitive and neural processes that enable the recognition of specific individuals. Although comparative studies suggest that similar cognitive processes underlie face recognition in chimpanzees and humans ([6-8] and Supplemental Data), it remains unknown whether chimpanzees also show face-selective activity in ventral temporal cortex. This study is the first to examine regional cerebral glucose metabolism with (18)F-flurodeoxyglucose positron emission tomography in chimpanzees after they performed computerized tasks matching conspecifics' faces and nonface objects (Supplemental Data). A whole-brain analysis comparing these two tasks in five chimpanzees revealed significant face-selective activity in regions known to comprise the distributed cortical face-processing network in humans, including superior temporal sulcus and orbitofrontal cortex. In order to identify regions that were exclusively active during one task, but not the other, we subtracted a resting-state condition from each task and identified the activity exclusive to each. This revealed numerous distinct patches of face-selective activity in the fusiform gyrus that were interspersed within a large expanse of object-selective cortex. This pattern suggests similar object form topography in the ventral temporal cortex of chimpanzees and humans, in which faces may represent a special class of visual stimulus.