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Speaker 1: slash brain Stuff. Welcome to brain Stuff from How Stuff Works. Hey,
Speaker 1: I'm Christian Sager and this is brain Stuff pop quiz
Speaker 1: hot shot. Have you ever tickled an ape? Before? It
Speaker 1: could work as tickling as common between many types of primates.
Speaker 1: What about a rat? You ever tickled one of those?
Speaker 1: You'd know if you had, because rats let out these little,
Speaker 1: high pitched chirps when you tickle them, kind of like
Speaker 1: rodent laughter. Okay, so maybe some of you beast masters
Speaker 1: out there have tickled both a rat and an ape.
Speaker 1: But can you tickle yourself? Probably not, because that is
Speaker 1: kind of impossible. Now, before we continue, let's do a
Speaker 1: quick primer on how tickling works. Under your skin. There
Speaker 1: are millions of nerve endings that alert your brain whenever
Speaker 1: you touch something. A light touch, what we usually associate
Speaker 1: with tickling, is analyzed by two regions of your brain,
Speaker 1: the somato sensory cortex, which processes touch, and the anterior
Speaker 1: singulated cortex, which processes happiness. Together they process the two
Speaker 1: types of tickle sensations we can experience. The first is nismesis.
Speaker 1: This is the light sensation you feel when something like
Speaker 1: a feather brushes against your skin, maybe giving you goose bumps.
Speaker 1: The second gargolesis is more like when your older brother
Speaker 1: holds you down and tickles you until you laugh so
Speaker 1: hard you pee your pants. This is the kind of
Speaker 1: tickling you can't replicate yourself. Evolutionary biologists believe that the
Speaker 1: reason we laugh when we're tickled is an innate, submissive
Speaker 1: response to a potential attacker. It's kind of like when
Speaker 1: a dog rolls over on its back and exposes its
Speaker 1: kill points to you. These same biologists theorized that we
Speaker 1: developed tickling so we could teach our children how to
Speaker 1: defend themselves from attacks. So think about it. The areas
Speaker 1: where we're the most ticklish, the under arms, the stomach,
Speaker 1: the neck, they're also the most vulnerable to attack. Now,
Speaker 1: this is some black Widow red room lethal training coming
Speaker 1: up here, so pay attention. Your under arm is home
Speaker 1: to veins and arteries, and because your rib cage doesn't
Speaker 1: protect it, someone could easily access your heart through there,
Speaker 1: especially with a long enough blade. Likewise, your stomach doesn't
Speaker 1: have any defensive bones, and your neck also has two
Speaker 1: important arteries as well as your trachea, bringing air to
Speaker 1: your lungs now We're aware of all of these points
Speaker 1: of vulnerability, but we still can't tickle ourselves at them
Speaker 1: because our brains know that our own hands don't pose
Speaker 1: a legitimate threat. Essentially, you can't tickle yourself because of
Speaker 1: self awareness. Mri I studies have shown that your seahbellum
Speaker 1: actually alerts the rest of your brain when you're about
Speaker 1: to tickle yourself. This filters it out as unnecessary information
Speaker 1: and mutes the sensation. So theoretically, any situation that confuses
Speaker 1: your brain's ability to predict its own actions should allow
Speaker 1: you to tickle yourself right well. Sometimes schizophrenics, for example,
Speaker 1: can tickle themselves. This is probably because their brains sometimes
Speaker 1: attribute their behavior to an alien source. Researchers theorized that
Speaker 1: schizophrenic brains have biochemical or structural variations that keep the
Speaker 1: cerebellum from alerting its owner when they're about to tickle themselves.
Speaker 1: This means they can't tell the difference between their hands,
Speaker 1: your hands, or the tentacles of a giant squint. Check
Speaker 1: out the brain stuff channel on YouTube, and for more
Speaker 1: on this and thousands of other topics, visit how stuff
Speaker 1: works dot com.