Fear is like hot porridge. Too much is bad. Not enough is bad. You want that balance to be just right. The amygdala is the part of the brain tasked with job of playing Goldilocks. If it's overactive, you'll end up a quivering ball of uselessness. If it's missing, you'll be an action-movie badass—right up until the point where you get yourself killed.
At least, that's how it worked in rats when researchers at the University of Washington put a terrifying, snappy-jawed LEGO robot between the rats and their food.
Faced with that threat, healthy rats quickly learned to snatch food that was just out of the robot's reach—while leaving the robot-guarded food alone. But amygdala-less rats just didn't care. They went after all the food, getting close enough to the Predator-Bot that they'd have likely been eaten had it been a Killer Predator-Bot. Meanwhile, rats with too much activity in their amygdala gave up on the food entirely, rather than get anywhere near the robot's toothy jaws.
And there are videos of this experiment. Chief among them: The robot's view of the situation.
(Thanks, hectocotyli!)
