Researchers Trigger Predatory Behaviors in Mice by Stimulating the Amygdala

In doing so, they found a switch that turns on the killer instinct of a mouse using a laser stimulator.

Hunger had a powerful influence on predatory behaviour – hungry mice were much more aggressive in their pursuit. “We could turn the neurons on and off based on our experimental design”.

“The system is not just generalized aggression”, de Araujo said. Mind control in mice: Attack!

A team from Yale university have managed to hack the brains of mice into highly efficient killing machines. The amygdala helps process memories while controlling both emotional responses and decision-making. The professor said that the key to understanding hunting instincts is how the brain is wired.

These prey-related sections of the amygdala are found in almost all vertebrates, but are absent in other species like the jawless lamprey fish, making the study of this brain area interesting from an evolutionary standpoint.

Researchers were specifically trying to learn about various animals’ feeding behaviors, the neural functions related to those behaviors, and how the biology of each has evolved over the centuries. However, when they conducted further tests they were able to determine the mice could still tell the difference between friend and food.

The mice were injected with a light-sensitive construct at the central nucleus of the amygdala.

“They’ve found these two behaviors – that are part of something we think of being very complex – are controlled by these two circuits”, says Cris Niell, a neuroscientist at the University of OR in Eugene who wasn’t part of the study. And another set that signals to the animal to use its jaw and neck muscles to bite and kill.

However, the aggression displayed by the killer mice was only towards objects that were smaller than them.

“Behavior was interrupted immediately upon laser deactivation”. Different areas in the brain were probed, until researchers stumbled upon the central region of the amygdala that controlled the mice’s muscles, the jaw, and the neck.

A statement from the research team said: “The mice take on qualities of “walkers” from [TV series] The Walking Dead, pursuing and biting nearly anything in their path”. Researchers noted that the aggressive behavior was not perceived at any time when the lasers were off. It works by genetically modifying neurons so their ion channels become sensitive to light, then using lasers to stimulate those neurons to “switch” them on and off. Scientists also found out that if they induced lesions in the amygdala region, the mice would pursue their prey but not kill it in the end.

A major evolutionary event right before the Cambrian period, half a billion years ago, led to the evolution of many predatory animal species.