Jealousy. Conceptual composite magnetic resonance imaging (MRI) brain scans demonstrating differences in jealousy between the sexes. At left is a man's response and at right is a woman's response (superimposed onto copies of the same brain scan). The hypothalamus is shown in red, with the woman's hypothalamus less active. Research has shown that in the brain the amygdala (controlling fear and aggression) and the hypothalamus (sexuality) are activated differently in men and women.