New Details on How the Brain Responds to Fear

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Whether you jump at the sight of a spider or work up a sweat at the mere mention of getting on an airplane, fears and phobias abound. (Image credit: Stockxpert.)

Some ostensibly important politician once said, "The only thing we have to fear…is that a mad scientist will learn how to directly manipulate the brain regions responsible for fear itself." Whoever that was, he or she could not have been more insightful.

Thanks to some recent work from the European Molecular Biology Laboratories (EMBL) and pharmaceutical company GlaxoSmithKline, fear itself might soon become the linchpin of this mad scientist's quest for world domination.

The group at EMBL is using mouse behavior to shed new light on the brain's response to hair-raising situations. Specifically, they're looking at the way we decide whether to freeze or flee when things get scary.

Their results, published in this month's issue of the journal Neuron, might change the way scientists think about the neural circuitry of fear, and the way that the Earth's citizens think about running for their lives.

Scaring mice

In order to understand the brain's actions in the face of danger, the researchers at EMBL needed precise control over the brain's danger zone – the amygdalae. The amygdalae are a pair of centrally located brain structures responsible for extreme emotions, like seething fury and bloodcurdling terror.

So they genetically engineered mice to have an extra receptor in their amygdalae that inactivates specific neurons in the presence of a drug. Just by administering the drug to these animals, the scientists were able to shut down a very specific population of cells while allowing the rodents to act relatively freely.

The researchers then trained these mutant mice to be wary of a noise that was associated with an electric shock.

Normally, the mice would freeze up in response to the sound. But when the amygdalae of these mice were knocked out, the mice reacted more actively – they would rear up and assess the danger instead of just quivering anxiously.

What this suggests is that it's the amygdalae that make our knees turn to jelly when we're spooked. This is big news for people interested in the neurobiology of fear, since the amygdalae were previously thought to be responsible for the fear response in general – behaviors like running around, hiding behind rubble, or yelling "Oh god, noooo," and not just the passive freezing response.

Manipulating fear in the masses

This is also big news for researchers who are trying to conquer the Earth. People responding actively to the threat of their imminent doom is actually the last thing that any mad scientist needs when he or she is trying to inspire fear and respect in the mindless hordes.

I don’t know if you've ever tried to unleash a horde of radioactive boars on a crowd of civilians, or fire a cold laser into an unsuspecting city, but in situations like this, people don't just freeze up, as much as you'd like them to. They run for cover, they try to stop the onslaught, they help each other out – it's all very frustrating for us evil geniuses. Some of my best-laid plans have been foiled by simpletons who don't know how to just stand there and wet themselves when faced with imminent destruction.

But with this new outlook on fear, I might be able to eliminate the chances of people ruining my schemes with their pesky displays of bravado. Next time I try to instill terror in the world's citizens, all I need to do is find a way to directly manipulate the amygdalae of my soon-to-be-subjects and switch on these neurons responsible for the freezing response. The world will be such an easy place to take over once I can force people to just cooperate.

Mad scientist Eric Schaffer has one index finger on the "fire death ray!" button and his other index finger on the exciting pulse of scientific research. His accounts of diabolical machinations, as well as research breakthroughs, appear regularly on LiveScience.