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Researchers Discover the Seat of Sex and Violence in the Brain


April 26, 2014
Brain & Behavior

As reported in a paper published online today in the journal Nature, Caltech biologist David J. Anderson and his colleagues have genetically identified neurons that control aggressive behavior in the mouse hypothalamus, a structure that lies deep in the brain (orange circle in the image at right). Researchers have long known that innate social behaviors like mating and aggression are closely related, but the specific neurons in the brain that control these behaviors had not been identified until now.

The interdisciplinary team of graduate students and postdocs, led by Caltech senior research fellow Hyosang Lee, found that if these neurons are strongly activated by pulses of light, using a method called optogenetics, a male mouse will attack another male or even a female. However, weaker activation of the same neurons will trigger sniffing and mounting: mating behaviors. In fact, the researchers could switch the behavior of a single animal from mounting to attack by gradually increasing the strength of neuronal stimulation during a social encounter (inhibiting the neurons, in contrast, stops these behaviors dead in their tracks).

These results suggest that the level of activity within the population of neurons may control the decision between mating and fighting.

The neurons initially were identified because they express a protein receptor for the hormone estrogen, reinforcing the view that estrogen plays an important role in the control of male aggression, contrary to popular opinion. Because the human brain contains a hypothalamus that is structurally similar to that in the mouse, these results may be relevant to human behavior as well.

The results of the study were published in journal Nature on April 16. David J. Anderson is the Seymour Benzer Professor of Biology and an investigator with the Howard Hughes Medical Institute.


12 Responses to Researchers Discover the Seat of Sex and Violence in the Brain

  1. u14135681 May 5, 2014 at 2:21 pm #

    It is absurd to say that men are more violent than women because during menstruation the levels of oestrogen drop and they find it more difficult than men to control their hormones. As much as you find men in prison,there are as much women as there are men in prison. Comparing humans to mice is ludicrous because most if not all animals act on instinct unlike human beings who are able to differentiate between right and wrong . You do find people who act on instinct thats why they are locked up like animals because they are not able to function in a civilised society. So saying that one gender is more violent than the other is wrong.

  2. u14042658 May 1, 2014 at 8:32 am #

    oestrogen is a very influencial hormone that makes men and women very different yet similar in certain ways. women have high levels of oestrogen which makes them calm and less aggressive as compared to men. women go though processes such as pregnancy and menstruation that makes these levels decrease, as a result makes them more comparable to men in their uncontrollable behaviour and sexual desire.

  3. u14044392 May 1, 2014 at 8:02 am #

    Somehow this article gives me the impression that the seat of sex and violence varies between males and females. I disagree. Both males and females can have the same degree of aggression and libido. For the same reason men are aggressive due to minimum amounts of oestrogen, females have a fluctuating process of hormones throughout their lives (Menstruation and Pregnancy) which makes them just as aggressive and sexually driven as males. The reason why there are more males behind bars simply does not mean they are more aggressive and sexually driven than females but instead females have a better logical level of thinking beyond just getting two minute pleasures from thrusting there gentiles into innocent people and the possibility of spending their lives behind bars.

    Lets not make excuses for stupidity.

  4. Lebohang(13381042) May 1, 2014 at 5:36 am #

    What are we supposed to believe now? Not long ago it was said that male aggression is caused by testosterone, now some researchers says it is estrogen. Science is contradicting itself!

  5. Camilla M. 14137594 May 1, 2014 at 4:39 am #

    How convenient that every time a human being either rapes or assaults someone it is blamed on the neurons or the DNA itself. It is funny how science contradicts itself on a daily basis. You wake up one morning to learn that male aggression is caused by testosterone and the next morning another researcher says its estrogen. Why cant science be conclusive in this pivotal field? I mean if we knew what causes people to be so aggressive we can help them before they hurt a whole lot of innocent people as well as themselves. It is high time this part of scientific research was given a lot of attention.

  6. Boipelo May 1, 2014 at 1:25 am #

    Knowing that estrogen is abundant in women and that men have the hormone but in very minute quantities,one would then ask if available quantities of the hormone account for the differences in aggressiveness of both genders??. The article has got me contemplating on the behaviour of men since men are generally known to be more aggressive than women, hence the high convictions of men in prison but also bearing in mind that women lose it sometimes, especially when they are pregnant or on their periods. This to me concludes that high quantities of estrogen in women account for their less aggressive behaviour as compared to men.However,sexual aggression certainly can go in any direction between and within genders.

  7. u13164270 May 1, 2014 at 12:47 am #

    less estrogen is equivalent to more sexual desire and aggression,men have the least amount of estrogen in comparison to women, which is why prisons are filled with men are killing and raping each other, because of the uncontrollable hormone that there neurons produce. Which bring up the question if we can really blame rapists for what they do? Can this hormone imbalance be changed? Does this justify why women are moody and more aggressive on their periods or when they are pregnant? Is the low amount estrogen to blame for almost all the infidelity and crime that we have?

  8. Inge Hugo (14022070) April 30, 2014 at 6:34 am #

    Knowing now where these neurons originate from we can further study how different stimuli can trigger this neuron other than just pulses of light, and the extent to which action (sex or violence) comes into play following these specific stimuli.
    The use of drugs and alcohol surely must have a huge affect on this area of the hypothalamus because people seem to get very sexual or very violent when either is taken. This is a breakthrough that will benefit future studies of sexual and violent behaviour and a hopeful future for people who want to pinpoint and prevent the stimulus that could cause them aggression or regretful behaviour.
    Scientists can now work on innovating and unique ideas for humans to control these behaviours especially for the ones who need to control it most.

  9. u14078024 April 28, 2014 at 12:33 pm #

    So by increasing the activity in these specific neurons in the brain the behaviour is changed from love to violence. Does this suggest that by limiting the activity of the neurons possibly chemically or electrically that aggression can be suppressed ending domestic and even global conflict? Would this truly be beneficial or would this simply lead to an onset of domination over those made incapable of resisting?

  10. u14056705 April 28, 2014 at 3:47 am #

    Violence is often an act of passion, but in a more dominant way. The feeling of love and sexual passion other than violence may awaken feelings of weakness, thus it is less difficult to carry out violent behaviour. This study of Caltech can help us to have a deeper understanding of behaviour among humans.

  11. u14025028 April 28, 2014 at 1:58 am #

    An act of violence can be seen as an act of passion, sexual intercourse also a passionate expression. It is intriguing that both violence and sex are extremely close and that a difference in stimulus can determine which act will take place. If humans react the same way that the mice did then people might be able to understand why domestic violence occurs in happy relationships and what can trigger the act of violence. It will open the societies understanding of why pain and pleasure are so closely related, and if society understands this then maybe when we have developed a further understanding for this subject people will learn to control the different actions and be able to control the stimulus. This can result in less domestic violence as well as a decrease in crimes of passion. The people who would have committed the crime can prevent it and carry on with a successful life, and the would have been victims won’t have to be afraid. Ultimately this breakthrough can change the lives of many people.

  12. Mkhululi April 27, 2014 at 7:27 am #

    The fact that the mating and aggression neurons in the brain are so close is very ironic and complements the phrase ” Love and war “. This can be used as an explanation as why lovers fight so much. However, i cannot help but to wonder if a person would able to be mount or attack another person if this person does not have these neuron.

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