Greg Gage: If I asked you to think of a ferocious killer animal,

Greg Gage如果我讓你想一個凶猛的殺人動物，

you'd probably think of a lion,

你'可能會想到獅子。

and for all the wonderful predatory skills that a lion has,

以及獅子的所有精彩的捕食技能。

it still only has about a 20 percent success rate at catching a meal.

它的捕食成功率仍然只有20%左右。

Now, one of the most successful hunters

現在，最成功的獵人之一

in the entire animal kingdom is surprising:

在整個動物王國中是令人驚訝的。

the dragonfly.

蜻蜓。

Now, dragonflies are killer flies,

現在，蜻蜓是殺手鐗。

and when they see a smaller fly,

而當他們看到一隻較小的蒼蠅。

they have about a 97 percent chance of catching it for a meal.

他們有大約97%的機會抓住它來吃。

And this is in mid-flight.

而這是在飛行中。

But how can such a small insect be so precise?

但是，這麼小的昆蟲怎麼會如此精準呢？

In this episode, we're going to see

在本期節目中，我們將看到'。

how the dragonfly's brain is highly specialized to be a deadly killer.

蜻蜓'的大腦是如何高度專業化，成為致命的殺手。

[DIY Neuroscience]

[DIY神經科學]

So what makes the dragonfly one of the most successful predators

那麼是什麼讓蜻蜓成為最成功的捕食者之一呢？

in the animal kingdom?

在動物界？

One, it's the eyes.

一，是眼睛。

It has near 360-degree vision.

它擁有近乎360度的視野。

Two, the wings.

二，翅膀。

With individual control of its wings,

以個人控制其翅膀。

the dragonfly can move precisely in any direction.

蜻蜓可以精確地在任何方向移動。

But the real secret to the dragonfly's success

但蜻蜓成功的真正祕訣'。

is how its brain coordinates this complex information

是其大腦如何協調這些複雜的資訊

between the eyes and the wings

兩眼之間

and turns hunting into a simple reflex.

並將狩獵變成了一種簡單的反射。

To study this, Jaimie's been spending a lot of time

為了研究這個問題，Jaimie'花了很多時間

socializing with dragonflies.

與蜻蜓交往。

What do you need to do your experiments?

你做實驗需要什麼？

Jaimie Spahr: First of all, you need dragonflies.

Jaimie Spahr:首先，你需要蜻蜓。

Oliver: I have a mesh cage to catch the dragonflies.

奧利弗我有一個網籠來抓蜻蜓。

JS: The more I worked with them, the more terrified I got of them.

JS：我和他們合作得越多，我就越害怕他們。

They're actually very scary, especially under a microscope.

他們'其實很可怕，尤其是在顯微鏡下。

They have really sharp mandibles, are generally pretty aggressive,

它們有非常鋒利的下頜骨，一般都很有攻擊性。

which I guess also helps them to be really good predators.

我想這也有助於它們成為真正的好獵手。

GG: In order to learn what's going on inside the dragonfly's brain

GG：為了瞭解蜻蜓的大腦內部發生了什麼'。

when it sees a prey,

當它看到獵物時。

we're going to eavesdrop in on a conversation

我們要去偷聽一個對話

between the eyes and the wings,

眼睛和翅膀之間。

and to do that, we need to anesthetize the dragonfly on ice

要做到這一點，我們需要麻醉冰上的蜻蜓。

and make sure we protect its wings so that we can release it afterwards.

並確保我們保護它的翅膀，這樣我們就可以在事後釋放它。

Now, the dragonfly's brain is made up of specialized cells called neurons

現在，蜻蜓的大腦是由專門的細胞組成的，叫做神經元。

and these neurons are what allow the dragonfly

而這些神經元是什麼讓蜻蜓

to see and move so quickly.

看得見，動得快。

The individual neurons form circuits by connecting to each other

各個神經元通過相互連接形成迴路

via long, tiny threads called axons

通過長長的、被稱為軸突的細線

and the neurons communicate over these axons using electricity.

而神經元通過這些軸突用電進行通信。

In the dragonfly, we're going to place little metal wires, or electrodes,

在蜻蜓中，我們'要放置小金屬線，或電極。

along the axon tracks,

沿著軸突軌道。

and this is what's really cool.

這是什麼'的真正的酷。

In the dragonfly, there's only 16 neurons;

在蜻蜓身上，只有16個神經元。

that's eight per eye

錙銖必較

that tell the wings exactly where the target is.

告知翅膀目標的確切位置。

We've placed the electrodes so that we can record from these neurons

我們已經放置了電極，這樣我們就可以從這些神經元中進行記錄了

that connect the eyes to the wings.

連接眼睛和翅膀的。

Whenever a message is being passed from the eye to the wing,

每當資訊從眼睛傳遞到翅膀時。

our electrode intercepts that conversation in the form of an electrical current,

我們的電極以電流的形式攔截對話。

and it amplifies it.

並將其放大。

Now, we can both hear it and see it in the form of a spike,

現在，我們既能聽到它的聲音，又能看到它的身影。

which we also call an action potential.

我們也稱其為行動電位。

Now let's listen in.

現在讓我們來聽聽。

Right now, we have the dragonfly flipped upside down,

現在，我們有蜻蜓倒轉。

so he's looking down towards the ground.

所以他向著地面俯視。

We're going to take a prey, or what we sometimes call a target.

我們'將採取獵物，或者我們有時稱之為目標。

In this case, the target's going to be a fake fly.

在這種情況下，目標'會是一隻假蒼蠅。

We're going to move it into the dragonfly's sights.

我們'要把它移到蜻蜓'的視線裡。

(Buzzing)

(嗡嗡聲)

Oh!

哦！

Oh, look at that.

哦，看那個。

Look at that, but it's only in one direction.

看，但它只在一個方向。

Oh, yes!

哦，是的！

You don't see any spikes when I go forward,

我向前走的時候，你看不到任何尖峰。

but they're all when I come back.

但他們'都是當我回來。

In our experiments,

在我們的實驗中。

we were able to see that the neurons of the dragonfly

我們能夠看到，蜻蜓的神經元。

fired when we moved the target in one direction but not the other.

當我們向一個方向移動目標而不向另一個方向移動時，就會發射。

Now, why is that?

現在，為什麼會這樣？

Remember when I said that the dragonfly

記得我說過，蜻蜓

had near 360-degree vision.

有近乎360度的視覺。

Well, there's a section of the eye called the fovea

好吧，有一個眼睛的部分稱為蜂窩。

and this is the part that has the sharpest visual acuity,

而這也是視力最敏銳的部分。

and you can think of it as its crosshairs.

你可以把它看成是它的十字線。

Remember when I told you the dragonfly had individual precise control of its wings?

還記得我跟你說過，蜻蜓的翅膀有單獨的精確控制嗎？

When a dragonfly sees its prey, it trains its crosshairs on it

當蜻蜓看到它的獵物時，它就會把它的十字線對準獵物

and along its axons it sends messages only to the neurons

並沿著它的軸突，它只向神經元發送信息。

that control the parts of the wings

控制翅膀的部分

that are needed to keep that dragonfly on target.

蜻蜓的目標需要。

So if the prey is on the left of the dragonfly,

所以如果獵物在蜻蜓的左邊。

only the neurons that are tugging the wings to the left are fired.

只有向左拽動翅膀的神經元才會被髮射。

And if the prey moves to the right of the dragonfly,

而如果獵物移動到蜻蜓的右邊。

those same neurons are not needed, so they're going to remain quiet.

那些相同的神經元是不需要的，所以他們&#39；要保持安靜。

And the dragonfly speeds toward the prey

蜻蜓向獵物飛去

at a fixed angle that's communicated by this crosshairs to the wings,

在一個固定的角度，'由這個十字線傳達給翅膀。

and then boom, dinner.

然後轟，晚餐。

Now, all this happens in a split second, and it's effortless for the dragonfly.

現在，這一切都發生在一瞬間，對蜻蜓來說毫不費力。

It's almost like a reflex.

它'幾乎是一種反射。

And this whole incredibly efficient process is called fixation.

而這整個令人難以置信的高效過程就叫做定身。

But there's one more story to this process.

但這個過程還有一個故事'。

We saw how the neurons respond to movements,

我們看到了神經元對運動的反應。

but how does the dragonfly know that something really is prey?

但蜻蜓怎麼知道某物真的是獵物呢？

This is where size matters.

這就是尺寸的重要性。

Let's show the dragonfly a series of dots.

讓'給蜻蜓看一連串的點。

Oh, yeah!

哦，是的！

JS: Yeah, it prefers that one.

JS：對，它更喜歡那個。

GG: Out of all the sizes,

GG：在所有尺寸中。

we found that the dragonfly responded to smaller targets over larger ones.

我們發現，蜻蜓對小目標的反應比對大目標的反應大。

In other words, the dragonfly was programmed to go after smaller flies

換句話說，蜻蜓被編程為去追捕小蒼蠅

versus something much larger, like a bird.

與更大的東西，如鳥類。

And as soon as it recognizes something as prey,

而一旦它認準了什麼東西是獵物。

that poor little fly only has seconds to live.

那隻可憐的小蒼蠅只有幾秒鐘的生命。

Today we got to see how the dragonfly's brain works

今天，我們看到了蜻蜓的大腦是如何工作的'。

to make it a very efficient killer.

以使其成為一個非常高效的殺手。

And let's be thankful that we didn't live 300 million years ago

讓我們慶幸我們沒有生活在3億年前。

when dragonflies were the size of cats.

當蜻蜓和貓一樣大的時候。