An innovative model developed for getting to know how aggression arises in the brain

Researchers at the Universitat Jaume I have developed a model that represents a significant advance toward understanding the brain mechanisms that trigger aggression. The model has been published in the journal Frontiers in Behavioural Neuroscience and is an innovative approach to analyse the brain area known as "the socio-sexual brain" by comparing brains of female mice under physiological situations in which their behaviour differs substantially.

The proposed method has been developed from the research of the PhD student of the Universitat Jaume I and the University of Valencia, Ana Martín Sánchez, in the framework of the preparation of her doctoral thesis at the Laboratory of Functional Neuroanatomy (NeuroFun) of the UJI. Thus, by studying the maternal behaviour of female mice, it was found that females who are mothers develop aggressive behaviour towards male mice, which virgin females do not show. As the Ph.D. student Ana Martín Sánchez explains, "A female is not usually aggressive. For her to attack, it is necessary her to be a mother and to have offspring to defend. We have seen that in these cases when approached by a male mouse, the female will attack him being as or more aggressive than a male."

Previous research of the group had shown that virgin females feel attracted by a pheromone that males expel in their urine. However, as the researcher Carmen Agustín says, "recent studies at the NeuroFun Laboratory of the UJI have shown that the same male pheromone that generates attraction on virgin females generates aggression on mother females." The brain area known as the "socio-sexual brain" determines this aggression. A primitive brain area, similar in all vertebrates, which is responsible for instinctive and non-cognitive behaviours, and therefore very difficult to control. The model developed by the researchers at the Universitat Jaume I will help to understand how this area of the brain manages our social behaviour.

In this sense, the proposed model will allow to understand how arises the aggressive behaviour in the brain from the study of an animal that goes into an aggressive model in a particular physiological situation as motherhood. As Ferran Martínez García explains, "the study indicates that when maternity comes, occurs a change in behaviour due to a change in the brain. We have an animal that enters in an aggressive mode reversibly. Through comparing the brains of virgin and mother females by studying their neuronal circuits or their gene expression patterns, we want to understand what brain changes make aggressive females during the breeding period. "To do this, the researchers of the group combine the analysis of animal behaviour with studies of the distribution of neurotransmitters and their receptors in the neurones of the socio-sexual brain.

The model developed by the NeuroFun group of the UJI is a major breakthrough for the study of the mechanisms that trigger aggression and would allow, by analysing those areas of the brain and the changes in the expression of certain genes, designing a pharmaceutical strategy for reducing aggression. Thus, this method provides a unique opportunity to discover the neuronal basis of aggression and its control mechanisms, but also to study other socio-sexual behaviours of enormous importance in our species as attraction or the maternal and paternal behaviours.

Bibliographic References:

Martín-Sánchez A, Valera-Marín G, Hernández-Martínez A, Lanuza E, Martínez-García F and Augustín-Pavón C (2015) Wired for motherhood: induction of maternal care but not maternal aggression in virgin female CD1 mice. Front. Behav. Neurosci. 9:197. doi: 10.3389/fnbeh.2015.00197

Martín-Sánchez A, McLean L, Beynon RJ, Hurst JL, Ayala G, Lanuza E, Martínez-García F. From sexual attraction to maternal aggression: when pheromones change their behavioural significance (2015) Horm Behav. 68:65-76. doi: 10.1016/j.yhbeh.2014.08.007

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