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  • (Music)

  • When you think about the brain,

  • it's sort of a difficult thing to understand,

  • because if I were to ask you right now, how does the heart work,

  • you would instantly tell me it's a pump. It pumps blood.

  • And if I were to ask you how your lungs work,

  • you would say it exchanges oxygen for carbon dioxide. That's easy.

  • Now if I were to ask you how the brain works, it's a hard thing to understand

  • because you can't just look at a brain and understand what it is.

  • It's not a mechanical object, it's not a pump, it's not an airbag.

  • It's just like, if you held it in your hand when it was dead, it's just a piece of fat.

  • And so to understand how the brain works,

  • you have to go inside a living brain. Because the brain's not mechanical,

  • the brain is electrical and it's chemical.

  • Your brain is made out of 100 billion cells,

  • and these cells are called neurons. And these neurons communicate with each other with electricity.

  • And we're going to eavesdrop in on a conversation between two cells,

  • and we're going to listen to something called a spike.

  • But we're not going to record my brain or your brain or your teacher's brains,

  • we're going to use our good friend the cockroach.

  • Not just because I think they're cool,

  • but because they have brains very similar to ours.

  • And so if you learn a little bit about how their brains work,

  • we're going to learn a lot about how our brains work.

  • So I'm going to put them in some ice water here

  • and then ...

  • (Audience: Ew!) ... yeah ...

  • So what's happening right now is that they're becoming anesthetized,

  • because they're cold blooded, they become the temperature of the water

  • and they can't control it so they just basically "chillax," right?

  • They're not going to be able to feel anything,

  • and that may just tell you a little bit about what we're going to be doing.

  • We're going to be doing a scientific experiment to understand the brain.

  • So ...

  • This is the leg of a cockroach

  • and a cockroach has all these beautiful hairs

  • and pricklies all over it.

  • Underneath each one of those is a cell,

  • and this cell's a neuron, and this neuron's going to send information

  • about wind or vibrations. If you ever try to catch a cockroach, it's hard

  • because they can feel you coming before you're even there, they start running.

  • So these cells are zipping up this information up to the brain

  • using those little axons with electronic messages in there.

  • So we're going to record by sticking a pin right in there.

  • So we need to take off the leg of a cockroach --

  • don't worry, they'll grow back --

  • then we're going to put two pins in there. One of the pins, these are metal pins,

  • will pick up this electronic message, this electric message is going by.

  • So, we're now going to do the surgery, let's see if you guys can see this.

  • Yeah, it's gross ...

  • All right ... so there we go ...

  • You guys can see his leg right there.

  • So now I'm going to take this leg, I'm going to put it in this invention that we came up with

  • called the Spikerbox --

  • and this replaces lots of expensive equipment in a research lab

  • so you guys can do this in your own high schools,

  • or in your own basements if it's me --

  • So, there. (Laughter)

  • Can you guys see that? Alright, so I'm going to go ahead and turn this on.

  • I'm going to plug it in. (Sound of neurons firing)

  • To me, this is the most beautiful sound in the world.

  • This is what your brain is doing right now.

  • You have 100 billion cells making these raindrop-type noises

  • So let's go ahead and take a look at what it looks like,

  • let's pull it up on the iPad screen

  • I plugged my iPad into here as well.

  • So remember what we said about the axon, what we said it looks like, looks like a spike.

  • So we're going to take a look at what one of them looks like in just a brief second.

  • We're going to tap here, so we can sort of average this guy.

  • So there we see it. That's an action potential.

  • You've got 100 billion cells in your brain doing this right now,

  • sending all this information back about what you're seeing, what you're hearing.

  • So we also said this is a cell that's going to be taking up information about vibrations in the wind.

  • So what if we do an experiment?

  • We can actually blow on this and hear if we see a change.

  • Are you guys going to be ready for this?

  • If I blow on it you tell me if you hear anything.

  • (Sound of spikes reacting to wind)

  • Let me just touch this with a little pen here.

  • (Noise)

  • That's actually the neural firing range. That actually took a while

  • in neuroscience to understand this. This is called rate coding,

  • which is that the harder you press on something, the more spikes there are,

  • and all that information is coming up to your brain. That's how you perceive things.

  • So that's one way of doing an experiment with electricity.

  • The other way is that your brain is not only taking in electrical impulses,

  • you're also sending out. That's how you move your muscles around.

  • Let's see what happens if I've plugged in something that's electric

  • into the cockroach leg here.

  • I'm going to take two pins, I'm going to plug them onto the cockroach.

  • I'm going to take the other end, I'm going to plug in into my iPod.

  • It's my iPhone actually.

  • I don't know if you guys know this, but do you guys know how your earbuds work in your ears?

  • You have a battery in your phone, your iPod, right?

  • It's sending electrical current into these magnets in your earbuds

  • which shake back and forth and allow you to hear things.

  • But that electric current's the same currency that our brain uses

  • so we can send that directly to our cockroach leg and hopefully if this works,

  • we can actually see what happens when we play music into the cockroach.

  • Let's take a look.

  • (Music beat) Can we turn it up? There we go.

  • (Music beats) (Audience reacts and gasps) So what's happening?

  • (Music beats)

  • So you see what's moving. It's moving on the bass.

  • All those audio files out there. If you have awesome, kicking car stereos,

  • you know, the bass speakers are the biggest speakers.

  • The biggest speakers have the longest waves, the longest waves have the most current,

  • and the current is what's causing these things to move.

  • So it's not just speakers that are causing electricity.

  • Microphones also cause electricity. (Beat)

  • So I'm going to go ahead and invite another person out on the stage here

  • to help me out with this. So there we go. (Beatboxing)

  • This is the first time this has ever happened in the history of mankind.

  • Human beatbox to a cockroach leg.

  • When you guys go back to your high school, think about neuroscience and how you guys can begin the neuro-revolution.

  • Thank you very much. Bye bye. (Applause)

  • (Music)

(Music)

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A2 TED-Ed cockroach brain leg electricity information

【TED-Ed】 The Cockroach Beatbox - Greg Gage

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    Calvin Chen posted on 2012/12/18
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