The neural correlates of mate competition in dominant male rhesus macaques

Background Male sexual jealousy provoked by threatened exclusive access to a female mate is a frequently reported motive in cases involving spousal abuse. Dominant male rhesus macaques also respond aggressively to threats to mating exclusivity. Methods Nine dominant male monkeys were injected with [18F]-fluorodeoxyglucose ([18F]-FDG) and then exposed to one of two conditions: a “challenge” condition in which they witnessed a potential sexual interaction between their female consort and a rival male, and a control condition in which the consort was present without the rival male. After the brain uptake period for [18F]-FDG, dominant males were sedated, blood samples were drawn, and regional cerebral glucose metabolism was measured with positron emission tomographic imaging. Results Males that showed larger increases in plasma testosterone in the challenge condition showed more aggression and greater activation in the central gray matter of the midbrain, a brain area rich in androgen receptors. The challenge condition was associated with activation in both right superior temporal sulcus and right amygdala, which might relate to increased social vigilance and anxiety, respectively. Conclusions Sexual jealousy in male humans is also often accompanied by vigilance behavior and anxiety and might recruit a similar neural network to that described here.