First exposure to an alive conspecific activates septal and amygdaloid nuclei in visually-naïve domestic chicks (Gallus gallus)

The septal nuclei are an evolutionarily well-conserved part of the limbic system, present in all vertebrate groups. Functionally, septal nuclei are involved in many important aspects of social behavior and lateral septum is considered a node of the social decision making network, together with amygdaloid nuclei. Given the importance of septal nuclei for social behaviors, it is somewhat surprising that it has never been investigated whether they are involved in early social responses of naïve animals. In the present study we wanted to know if simple exposure of visually naïve newly hatched chicks to a visual object (an alive, behaving conspecific), that also contains all features to which chicks are known to express early social predispositions, will selectively activate septal areas. We measured brain activity by visualizing the immediate early gene product c-Fos with a standard immunohistochemical procedure. Notably, after a brief visual exposure to an alive behaving conspecific septu...