Short-latency preference for faces in primate superior colliculus depends on visual cortex.

Face processing is fundamental to primates and has been extensively studied in higher-order visual cortex. Here, we report that visual neurons in the midbrain superior colliculus (SC) of macaque monkeys display a preference for images of faces. This preference emerges within 40 ms of stimulus onset-well before "face patches" in visual cortex-and, at the population level, can be used to distinguish faces from other visual objects with accuracies of ∼80%. This short-latency face preference in SC depends on signals routed through early visual cortex because inactivating the lateral geniculate nucleus, the key relay from retina to cortex, virtually eliminates visual responses in SC, including face-related activity. These results reveal an unexpected circuit in the primate visual system for rapidly detecting faces in the periphery, complementing the higher-order areas needed for recognizing individual faces.