Furthermore, patients with those lesions could discriminate known from unknown faces, gaze directions, and facial expressions ( de Gelder et al., 1999 Tamietto and de Gelder, 2010 Burra et al., 2013 Solcà et al., 2015 Bertini et al., 2019). A blindsight patient with visual cortical lesions showed residual visual functions they were able to unconsciously distinguish between normal faces and faces with arbitrarily placed facial features ( Solcà et al., 2015), suggesting a subcortical involvement in visual processing. Accumulating evidence from human neuropsychological studies suggests the existence of the subcortical face processing pathway, which consists of the SC, pulvinar, and amygdala ( Tamietto and de Gelder, 2010 Rafal et al., 2015). The SC, one of the subcortical visual areas, is phylogenetically old and might support innate visual recognition in vertebrates ( Sewards and Sewards, 2002 Carr, 2015). These behavioral data suggest that the vertebrate brain may have an innate face processing system or an innate prototypical face template (“Conspec” Morton and Johnson, 1991). In other vertebrate species, newly hatched chicks or chicks reared in dark, in which the optic tectum is the homolog of the mammal SC ( Butler and Hodos, 2005), show preference for the similar schematic face-like figures and photos of human faces ( Rosa-Salva et al., 2010, 2011). For example, infant monkeys reared without exposure to faces still reacted stronger to conspecific pictures as well as human faces compared with non-face objects ( Sackett, 1966 Sugita, 2008). This proposal is further supported by studies in other species. During this early period in life when the cortical visual systems are still immature, the subcortical visual areas including the superior colliculus (SC) are proposed to convey facial information to the extrastriate cortices ( Johnson, 2005). Newborn babies orient toward faces and schematic face-like figures (three filled circles on a bright ellipse Johnson et al., 1991). Our results provide strong neurophysiological evidence for the involvement of the primate SC in face detection and suggest the existence of a broadly tuned template for face detection in the subcortical visual pathway. In addition, the population activity of SC neurons with central RFs can discriminate face-like patterns from nonface patterns as early as 50 ms after the stimulus onset. Furthermore, SC neurons with central receptive fields (RFs) were more selective to face-like patterns. Here, we show that SC neurons respond stronger and faster to upright and inverted face-like patterns compared to the responses to nonface patterns, regardless of contrast polarity and contour shapes. To test this hypothesis, we examined the responsiveness of monkey SC neurons to first-order information of faces required for face detection (basic spatial layout of facial features including eyes, nose, and mouth), by analyzing neuronal responses to line drawing images of: (1) face-like patterns with contours and properly placed facial features (2) non-face patterns including face contours only and (3) nonface random patterns with contours and randomly placed face features. We hypothesized that the superior colliculus (SC) that receives direct and indirect retinal visual inputs may serve as an innate rapid face-detection system in primates. However, in primates, the visual area responsible for this process is yet to be unraveled. It has been proposed that an innate and rapid face detection system is present at birth before the cortical visual pathway is developed in many species, including primates. Human babies respond preferentially to faces or face-like images. 3Laboratory of Neuroscience and Behavior, CEUMA University, São Luis, Brazil.2Primate Center and Laboratory of Neurosciences and Behavior, Department of Physiological Sciences, Institute of Biology, University of Brasília, Brasilia, Brazil.1System Emotional Science, Faculty of Medicine, University of Toyama, Toyama, Japan.Maior 2 Carlos Tomaz 3 Taketoshi Ono 1 Hisao Nishijo 1* Quang Van Le 1† Quan Van Le 1† Hiroshi Nishimaru 1 Jumpei Matsumoto 1 Yusaku Takamura 1 Etsuro Hori 1 Rafael S.
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