A flash of light has turned on predatory instincts in mice, leading them to pounce on potential prey and display a range of hunting and killing acts.

Brain circuits involved in predatory activities are still largely mysterious, with previous research maintaining that the amygdala, the brain’s center of emotion and motivation, activates when rats are on the prowl. Yale University researchers suggested this brain region indeed controls hunting behaviors.

Turning Into Ravenous "Walkers"

The team used optogenetics, a technique that leads neurons into firing once light hits them. After infecting the mouse subjects with a virus that made their brain neurons sensitive to blue light, they shone a blue laser on the amygdala, prompting the creatures to tense muscles in their jaw and neck.

They turned the laser on and the mice became no different from walkers in The Walking Dead: hunting everything that crossed their paths, from wood sticks to bottle caps, and jumping on objects and biting them as if on hunting mode. This went on even if there was actually nothing to hunt.

Predatory hunting involves massively complex behaviors in both humans and vertebrate animals.

"It is a major evolutionarily player in shaping the brain. There must be some primordial subcortical pathway that connects sensory input to the movement of the jaw and the biting,” said lead study investigator and psychiatry professor Ivan de Araujo in a statement.

Friend Or Food? Mice Still Know, Study Says

Hunger appeared to affect predation, with light-activated mice that were hungry more aggressively chased after prey than their peers that were not hungry. However, laser-activated mice still recognized friend and food.

“When they were with another mouse, they might have become more curious, but we didn’t observe any attacks,” de Araujo said, explaining that their experiment potentially triggered predation and not necessarily aggression or hunger.

It was previously believed that the role of the central amygdala ended in fear, but current research offered a different perspective: the brain region is actually part of complex behaviors like grooming and can actually trigger predation.

Since the central amygdala plays a part in so many behaviors, future inquiries can delve into the specific neuron circuits involved in hunting. The question: what part of the brain governs hunting, and how do those decisions emerge in the first place?

de Araujo added that this helps in understanding how the brain works on a massive scale, including how its neurons recruit various areas to perform a single task. However, there’s no need to fear killer mice as the brain regions activated by their pouncing and killing were involved in highly specific actions — “as opposed to an uncontrolled killer instinct,” the researcher clarified.

The findings were discussed in the journal Cell.

In a separate study this week, a Tarantula spider was documented devouring a snake under a rock, surprising scientists due to the foot-length size of the snake versus the tiny size of the predator spider, which was just a fraction of the former. It was the first ever recorded incident of that specific predatory act in the wild.