Mean ± SEM Fos-ir expression across SBN nodes in non-bonded (left) and pair bonded (right) male prairie voles across contexts. Color gradation represents mean Fos-ir cell counts with dark blue representing 0 cells and dark red representing greater than 200 cells. Abbreviations: anterior hypothalamus (AH), bed nucleus of the stria terminalis (BST), lateral septum (LS), medial amygdala (MeA), periaqueductal gray (PAG), preoptic area (POA), ventromedial hypothalamus (VMH).