Cited research Proc. Natl Acad. Sci.USA doi:10.1073/pnas.1001394107 (2010)

Success in physical conflict can boost fighting ability in animals, possibly because of a post-bout release of testosterone. A study in a territorial species of mouse shows how the brain changes after several victories and that winning on home turf seems to enhance this effect.

Matthew Fuxjager at the University of Wisconsin, Madison, and his colleagues looked at the expression of androgen receptors, which respond to testosterone, in nine brain areas in captive California mice (Peromyscus californicus; pictured) that had won several territorial disputes. They found higher expression in three areas associated with social aggression, motivation and reward. But in two of these areas, expression was elevated only when the animals had fought in their own cages. These home-turf winners were more likely to win future encounters. B.M.

Credit: M. FUXJAGER