Adult male mice have a simple repertoire of innate, or instinctive, social behaviors: When encountering a female, a male mouse will try to mate with it, and when encountering another male, the mouse will attack. The animals do not have to be taught to perform these behaviors. This has led to the widespread presumption among neuroscientists that the brain circuits mediating these behaviors are “hardwired,” meaning that they are genetically encoded pathways with little flexibility. But new research from Caltech neuroscientists shows that these behaviors and the neurons that represent them are not as fixed as previously believed. “This is an unexpected discovery,” says co-first author Ann Kennedy, a Caltech postdoctoral scholar in biology and biological engineering. “This area of the brain, the ventromedial hypothalamus, is a primitive, ancient region. We used to think of it as the basement of the brain, more like a plumbing system than a computer. Our study shows that this region exhibits plasticity and computation.”
The paper is titled “Social behaviour shapes hypothalamic neural ensemble representations of conspecific sex.”