To activate the central amygdala in mice, Ivan de Araujo, a neurobiologist at Yale University in New Haven, Connecticut, and his colleagues used a technique called optogenetics. First, they infected the mice with a virus that made the neurons in their brains sensitive to blue light. Then, the researchers used a tiny optic fibre to shine a blue laser on the amygdala. This prompted the animals to tense their jaw and neck muscles. The behaviour didn’t occur when the researchers stimulated other parts of the brain.
When the laser was on, the mice hunted just about everything placed in their paths