[Neural Mechanisms of Innate Recognition of Facial Stimuli in Primates].

Primates can recognize or respond to specific stimuli that are important for survival, such as faces, predators, prey animals, and foods, even if they have not experienced those stimuli previously (innate recognition). Throughout vertebrates, including primates, the extrageniculate visual system (subcortical visual pathway) comprising the retina, superior colliculus, pulvinar, and amygdala is thought to be genetically hard-wired and involved in innate recognition of these stimuli. To investigate neural mechanisms of innate recognition in primates, we analyzed single neuronal responses to facial images in the monkey pulvinar and superior colliculus. The results indicated that the pulvinar and superior collicular neurons responded preferentially to facial images in short latency and showed gamma oscillations during stimulus presentation. Furthermore, the population activity of these neurons discriminated head direction, sex, and identity of facial images. Based on these findings, we discussed neural mechanisms underlying the innate and automatic (unconscious) detection of facial stimuli in the extrageniculate visual system.