Subpallial and hypothalamic areas activated following sexual and agonistic encounters in male chickens

Male sexual and agonistic behaviors are controlled by the common social behavior network, involving subpallial and hypothalamic brain areas. In order to understand how this common network generates different behavioral outcomes, induction of FOS protein was used to examine the patterns of neuronal activation in adult male chickens following interaction with a female or a male. Males were subjected to one of the following treatments: handling control, non-contact interaction with a female, contact interaction with a live female, a taxidermy female model or another male. The number of FOS-immunoreactive (FOS-ir) cells, and the area and immunostaining density of individual cells were quantified in the medial preoptic nucleus (POM), medial extended amygdala (nucleus taeniae of the amygdala, TnA, and dorsolateral and ventromedial subdivisions of the medial portion of the bed nucleus of stria terminalis, BSTM1 and BSTM2, respectively), lateral septum (SL), hypothalamic paraventricular nucleus (PVN), bed nucleus of the pallial commissure (NCPa) and ventrolateral thalamic nucleus (VLT). An increase in FOS-ir cells following appetitive sexual behavior was found in BSTM2 and NCPa. Copulation augmented FOS-ir in POM, SL, VLT, and PVN. Intermale interactions increased FOS-ir in all examined brain regions except the TnA and BSTM. Within the SL, copulatory and agonistic behavior activated spatially segregated cell groups. In the PVN, different social behaviors induced significant changes in the distribution of FOS-ir cell sizes suggesting activation of heterogeneous subpopulations of cells. Collectively, behavioral outcomes of male–female and male–male interactions are associated with a combination of common and site-specific patterns of neural activation.