The Neural Mechanisms of Sexually Dimorphic Aggressive Behaviors

• Published in: Trends in genetics Vol. 34; no. 10; pp. 755 - 776
• Main Authors: Hashikawa, Koichi, Hashikawa, Yoshiko, Lischinsky, Julieta, Lin, Dayu
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2018
• Subjects: Aggression - physiology; Animals; Brain - physiology; Female; Male; Selection, Genetic - genetics; Selection, Genetic - physiology; Sexual Behavior, Animal - physiology
• ISSN: 0168-9525
• DOI: 10.1016/j.tig.2018.07.001

Aggression is a fundamental social behavior that is essential for competing for resources and protecting oneself and families in both males and females. As a result of natural selection, aggression is often displayed differentially between the sexes, typically at a higher level in males than females. Here, we highlight the behavioral differences between male and female aggression in rodents. We further outline the aggression circuits in males and females, and compare their differences at each circuit node. Lastly, we summarize our current understanding regarding the generation of sexually dimorphic aggression circuits during development and their maintenance during adulthood. In both cases, gonadal steroid hormones appear to play crucial roles in differentiating the circuits by impacting on the survival, morphology, and intrinsic properties of relevant cells. Many other factors, such as environment and experience, may also contribute to sex differences in aggression and remain to be investigated in future studies. Depending on the species, aggressive behaviors can differ both quantitatively and qualitatively between sexes. In rodents, social experiences, including social isolation, mating, winning, and losing, impact differentially on aggressive behaviors between sexes. Similar brain regions mediate male and female aggression in mice, although the number and response intensity of relevant cells may differ. Sex hormones, such as estrogen and androgen, play important roles during development to differentiate male and female aggression circuits. Sex hormones are necessary to maintain a high level of aggression in adult male mice but not in female mice.