Valencian researchers developed an innovative model to understand how aggression arises in the brain

Researchers at the University of Jaume I (UJI) developed a model that represents an important advance toward understanding the brain mechanisms that trigger aggression.

The model has been published in the journal Frontiers in Behavioral Neuroscience and is an innovative approach to analyse the brain area known as "the socio-sexual brain" by comparing brains of female mice under two physiological situations in which their behaviour differs substantially.

The proposed method has been developed from research done by Ana Martín Sánchez, PhD student of the University Jaume I and the University of Valencia, while preparing her doctoral thesis at the Laboratory of Functional Neuroanatomy (NeuroFun) at the UJI.

The study compared the behaviour of females who are mothers and of virgin females exposed to foster pups. Virgin females quickly developed maternal-like responses towards the pups; however, whereas mothers aggressively defended the nest of intruder males, virgin females did not develop aggressive responses.

"Usually, a female is not aggressive. To attack, the female has to be a mother and have pups to defend. We have seen that in this case, when a male mouse approached her, the female will attack him being as aggressive as a male or even more." Ana Martín Sánchez explained.

Previous research from the group had shown that virgin females are attracted to a pheromone that males expel in their urine. But as underlines the researcher Carmen Agustín, "recent studies at NeuroFun Laboratory at the UJI have shown that the same male pheromone that attracts a virgin females, triggers the aggressive responses of lactating females."

The researchers at UJI hope to shed light on how aggressive behaviour arises in the brain by studying how an animal becomes aggressive in a defined physiological state, i.e. motherhood. As Ferran Martínez García explains, "The study indicates that a temporarily, reversible change in behaviour occurs with maternity due to a change in the brain". The aggression response is likely controlled by the brain area known as the "socio-sexual brain", a primitive brain area, similar in all vertebrates, which is responsible for instinctive behaviours, non-cognitive, and therefore very difficult to control.

The next step is to investigate the changes that motherhood induces in the areas of the socio-sexual brain of mice, by comparing the distribution of neurotransmitters and their receptors and the patterns of gene expression in these areas in mothers and virgins. Hopefully, these studies will allow to design a drug strategy to reduce aggression. This method provides a unique opportunity to investigate the neural basis of aggression and its mechanisms of control, but also to study other socio-sexual behaviours of enormous importance for our species, such as attraction and parental behaviour.