Every October, millions of people line up to enter haunted houses, knowing full well that — behind a curtain, down a dark hallway — someone will jump out screaming. The heart accelerates, the eyes widen, the legs tremble. Yet, as soon as the monster retreats, we find ourselves laughing, not running away.
Here’s the paradox: we love to be afraid, but only when we know it won’t really hurt us. It is a form of “controlled adrenaline”, a little training for the brain, which simulates danger without paying the consequences.
According to new research conducted by the University of Colorado Boulder and published in Molecular Psychiatryeverything would depend on a tiny circuit in the brain, called interpeduncular nucleus (IPN), capable of turning the internal alarm on and off when the brain distinguishes a real danger from a perceived one.
How the brain learns to distinguish real danger from “fake thrill”
The team led by professor Susanna Molas and researcher Elora Williams studied the behavior of some mice in a curious experiment: a sort of infested house for rodents. For three consecutive days, an ominous shadow was cast over their heads.
On the first day the mice, terrified, froze. On the second day they began to react with less fear. By the third time, the shadow was no longer effective. And their brains showed it: the IPN cells — which were “brightening” with activity on the first day — shut down as the animals realized that the danger wasn’t real.
In practice, the brain learned to modulate fear, just like we do when we watch a horror film or enter a haunted house: we know that we are not risking our lives, but we let the adrenaline do its work, because – let’s face it – we like to feel it flowing. Williams explained:
Fear is like an alarm. It must sound when the danger is real, but it must also go off when it is no longer needed. Our brain learns to regulate it with experience.
Good adrenaline, bad fear and the (very thin) border between the two worlds
When the IPN works well, it allows us to feel strong emotions without getting trapped by them. But if this circuit is broken, fear stays on even when it shouldn’t. This is what happens, according to scientists, in disorders such as chronic anxiety or post-traumatic stress disorder (PTSD).
Those who love extreme sports, on the other hand, may have a “lazy” IPN: their brain does not perceive danger with the same intensity, and this explains why some of us constantly chase the thrill.
Ultimately, human beings don’t just look for security: they look for intensity. It’s the same impulse that drives us to watch scary movies, read thrillers, or tell ghost stories by the fire. Fear, when we know we can control it, becomes a form of mental pleasure.
It’s a way of telling ourselves, “I’m alive. I’m scared, but I can handle it.” And this, more than any Halloween candy, is the real prize we take home.
When the brain teaches us courage
The work of the Molas team does not limit itself to explaining fear: it opens new therapeutic perspectives. Understanding how IPN works could in fact lead to new targeted treatments for anxiety disorders.
Because, in the end, Halloween is not just a festival of masks and pumpkins: it is a collective ritual of emotional training. We learn to live with the dark, with the unknown, with what scares us. But in a safe, protected way, within the confines of a game.
And it is right there, in that precarious balance between terror and laughter, that the brain finds its magic: fear doesn’t paralyze us, it trains us. It teaches us when to run… and when to stay.
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