Scientists find 'root of all evil'
The "root of all evil" has been discovered by scientists who found that part of the brain fires up before nefarious acts are carried out. Researchers wanted to find out if bad intentions could be seen forming in the brain before any violence or aggression took place. They found that a distinct part of the hypothalamus - the brain region that controls body temperature, hunger and sleep - is activated shortly before an attack.The study authors, from New York University, say it may be possible to spot early warning signs of premeditated violence, stalking, bullying and even sexual aggression, and prevent it occurring for good."Our study pinpoints the brain circuits essential to the aggressive motivations that build up as animals prepare to attack," said study senior investigator Dayu Lin, of the Neuroscience Institute at NYU Langone.The part of the brain that switches on before aggressive behaviour is known anatomically as the ventro-lateral part of the ventromedial hypothalamus, or VMHvl, because of its central location inside the brain on the underside of the hypothalamus.Researchers say the finding could lead to drugs that help people control violent behaviour, without the need for restraints or sedation. It might even be possible to monitor brain activity continually and alert health experts or the security services before an aggressive attack.But the work is likely to prove controversial as drugs to prevent aggression or monitoring might be seen as preventing free will, which would raise ethical concerns.Lin said targeting this part of the brain to curb aggression remains "only a distant possibility, even if related ethical and legal issues could be resolved. That said, our results argue that the ventrolateral part of the ventromedial hypothalamus should be studied further as part of future efforts seeking to correct behaviours from bullying to sexual predation."For the study, male mice were trained to attack weaker males and then monitored to see how aggressively they tried to gain access to, and bully, another mouse.One measure used to gauge aggression was counting the number of attempts made by mice to wiggle through small holes that led to another mouse, which they could then attack. The mice were fitted with probes that measured nerve activity before, during and after they planned the attack. The researchers found nerve cell activity in the VMHvl routinely peaked just before mice began to poke through the holes.Nerve cell activity in the VMHvl also increased up to tenfold during the initial seconds after the weaker target mice appeared. However, genetically stopping VMHvl activity caused the aggressive mice to stop attacking.The researchers say it is possible the region is linked to reward centres of the brain that make an attack seem more desirable and may promote a flow of endorphins.The study tracked the premeditated, motivational aspect of the behaviour to the VMHvl.Lin' s laboratory plans to investigate which nerve cells and circuits in the VMHvl are involved in carrying out aggression.The research was published in Nature Neuroscience. Lead author Annegret Falkner said: "Little is known about the neural mechanisms that promote self-initiated aggression-seeking when no threat is present."We found that the [VMHvl] was essential for aggression-seeking. Inactivation of the VMHvl reduced aggression-seeking behaviour, whereas stimulation of the VMHvl accelerated moment-to-moment aggression-seeking and intensified future attacks."