Dopaminergic activity modulation via aggression, status, and a visual social signal.

Social interaction may elicit aggression, establish social rank, and be influenced by changes in central dopaminergic activity. In the lizard Anolis carolinensis, a sign stimulus (darkening of postorbital skin or eyespots) inhibits aggressive response from opponents, in part because it forms more rapidly in dominant males. The authors report that artificially hiding or darkening eyespots influences central dopaminergic activity, social status, and aggression during dyadic social interaction. All males that viewed an opponent with eyespots painted black became subordinate and exhibited elevated dopamine in raphe, lateral amygdala, and medial amygdala but decreased dopamine in septum and locus ceruleus. In contrast, males that viewed opponents with hidden eyespots (painted green) became dominant and had increased dopamine in striatum, nucleus accumbens, hypothalamus, and combined substantia nigra/ventral tegmental area.