Neuronal correlates of early social behaviour in visually naive domestic chicks (Gallus gallus)

The detection of animate creatures, such as conspecifics, preys or predators, is crucial for survival of animals already at the onset of life. Behavioural studies conducted in newly hatched, visually-naive domestic chicks (Gallus gallus), demonstrated preferences for visual stimuli that resemble conspecifics (e.g. a stuffed fowl over a less naturalistic one) or that display static and dynamic features typical of animate objects (e.g., face-like or biologically-moving stimuli). However, the neuronal mechanisms mediating this phenomenon are mostly unknown. We conducted a series of experiments to investigate this issue in chicks (hatched in dark incubators and tested directly after birth), by mapping neuronal activity through immediate early genes expression. The experiments revealed that exposure to the static configuration of features or to the natural motion typical of conspecifics stimulated differential activation in the amygdaloid, septal and preoptic nuclei. These areas are part of the so-called ‘‘social behaviour network”, which is shared among all vertebrates and comprises interconnected areas rich in sex steroid receptors and implicated in adult social behaviours. Overall, the results of my works demonstrate that important nodes of the social behaviour network are already engaged in social responses at birth: previous learning experiences associated with social companions are not needed for their involvement in this function.