Face Processing in the Chimpanzee Brain
SummaryHuman face recognition involves highly specialized cognitive and neural processes that enable the recognition of specific individuals [1–5]. 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 18F-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 [9–11]. 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.