From Nature:
Sex and violence are intertwined in mice. A tiny patch of cells buried deep within a male's brain determines whether it fights or mates, and there is good reason to believe humans possess a similar circuit. The study, published in Nature today1, shows that when these neurons are quieted, mice ignore intruding males they would otherwise attack. Yet when the cells are activated, mice assault inanimate objects, and even females they ought to court. The cells lie within an area of the hypothalamus with known links to violent behaviour. An electrical jolt to this vicinity causes cats and rats to turn violent, but neurophysiological experiments conducted decades ago stimulated too big an area to identify the specific brain circuits, let alone the individual neurons, involved in aggression.
More recently, scientists studying mice engineered to lack specific genes have found that some of them act more aggressively than normal mice. “We really don't know which part of the brain went wrong in those mice. Consequently it's tough to make sense of that behaviour,” says Dayu Lin, a neuroscientist now at New York University and an author of the study, who began searching for the seat of aggression in mice while working with David Anderson at the California Institute of Technology in Pasadena.
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