At first glance, the human brain seems to be ruled by mob mentality. Billions of nerve cells shout to one another by firing electrical impulses, controlling how the brain's owner behaves. But within that mob of nerve cells, or neurons, are specialists that do their own thing. Some cells ignore all but one specific sort of stimulus, then fire at will when encountering their specialty.
Many neurons respond best to faces, others to animals, some to houses.
And one neuron fires like crazy at the sight of an angry female face. For many men, that neuron works overtime. It's not easy, though, to find out what any one nerve cell's job is. Brain waves measured from outside the scalp reflect the signals from many cells, as do brain scans that measure brain activity by recording blood flow. Much of what scientists know about single neurons, therefore, is acquired from tiny electrodes implanted in the brains of animals, especially macaque monkeys or other primates.