Development of the Multimodal Integration in the Superior Colliculus and Its Link to Neonates Facial Preference

Abstract

The question whether newborns possess inborn social skills is a long debate in developmental psychology. Fetal behavioral and anatomical observations show evidences for the control of eye movements and facial behaviors during the third trimester of pregnancy whereas specific sub-cortical areas, like the superior colliculus (SC) and the striatum appear to be functionally mature to support these behaviors. These observations suggest that the newborn is potentially mature for developing minimal social skills. In this talk, we propose that the mechanism of sensory alignment observed in SC is particularly important for enabling the social skills observed at birth such as facial preference and facial mimicry. In a computational simulation of the maturing superior colliculus connected to a simulated facial tissue that replicate some attributes of the bio-mechanical properties of the fetus' face, we model how the incoming tactile information is used to direct visual attention toward faces. We suggest that the unisensory superficial visual layer (eye-centered) in SC and the deep somatopic layer (face-centered) in SC are combined into an intermediate layer for vision-tactile integration and that multi-modal alignment in this third layer allows newborns to detect faces and to mimic them. After we complete the learning stage within each map through Hebbian reinforcement learning, we show that the intermediate layer develops vision-tactile sensory alignment which respects the topology of the visuotopic map and of the facial map. We observe emergent properties of the global network such as sensitivity to the orientation of face-like patterns and detection of facial expressions. Although neonate imitation is only a marker that disappears after 2-3 months in human and lets place to whole body imitation starting in human 9-12 months, we propose that the superior colliculus plays a key role in the perinatal period to bootstrap the immature cortex to develop its social abilities.