Electrical experiments with plants that count and communicate | Greg Gage

譯者: Lilian Chiu 審譯者: Helen Chang

I'm a neuroscientist,

我是神經科學家，

and I'm the co-founder of Backyard Brains,

我是 Backyard Brains （後院頭腦）的共同創辦人，

and our mission is to train the next generation of neuroscientists

我們的使命是要訓練 下一代的神經科學家，

by taking graduate-level neuroscience research equipment

做法是把研究所等級的 神經科學研究設備

and making it available for kids in middle schools and high schools.

開放給國中和高中的孩子使用。

And so when we go into the classroom,

我們進到教室，

one way to get them thinking about the brain, which is very complex,

使學生思考複雜頭腦的方式之一

is to ask them a very simple question about neuroscience,

是問他們一個非常 簡單的神經科學問題，

and that is, "What has a brain?"

那就是：「什麼有頭腦？」

When we ask that,

當我們問這個問題，

students will instantly tell you that their cat or dog has a brain,

學生會馬上告訴你， 他們的貓或狗有頭腦，

and most will say that a mouse or even a small insect has a brain,

大部份人會說，老鼠、 甚至小昆蟲也有頭腦，

but almost nobody says that a plant or a tree

但幾乎沒有人會說植物、樹木

or a shrub has a brain.

或灌木有頭腦。

And so when you push --

當你再進一步──

because this could actually help describe a little bit

因為這其實可以稍微協助描述

how the brain actually functions --

頭腦實際上如何運作──

so you push and say,

所以當我們再進一步問說：

"Well, what is it that makes living things have brains versus not?"

「生物有沒有頭腦的差別在哪？」

And often they'll come back with the classification

通常，他們回答的分類是

that things that move tend to have brains.

會動的生物通常有頭腦。

And that's absolutely correct.

那完全正確。

我們的神經系統是用電的， 所以會進化。

Our nervous system evolved because it is electrical.

It's fast, so we can quickly respond to stimuli in the world

它很快，所以我們能對世界上的 刺激物做出快速反應，

and move if we need to.

有需要我們也會移動。

But you can go back and push back on a student,

但你可以回頭去再問學生：

and say, "Well, you know, you say that plants don't have brains,

「你說植物沒有頭腦，

but plants do move."

但植物確實會動。」

Anyone who has grown a plant

只要你曾經種過植物，

has noticed that the plant will move

就會注意到植物會動，

and face the sun.

它會面向太陽。

But they'll say, "But that's a slow movement.

但他們會說：

「但那是很緩慢的移動，不算數。

You know, that doesn't count. That could be a chemical process."

那可能是種化學過程。」

But what about fast-moving plants?

那動得很快的植物呢？

Now, in 1760, Arthur Dobbs, the Royal Governor of North Carolina,

1760 年，北卡羅來納的 皇家總督阿圖杜伯斯

made a pretty fascinating discovery.

有個非常棒的發現。

In the swamps behind his house,

在他家後面的沼澤中，

he found a plant that would spring shut

他發現一種植物，

每次只要有一隻蟲落入它中間，

every time a bug would fall in between it.

它就會飛快闔上。

He called this plant the flytrap,

他把這植物稱為捕蠅草，

and within a decade, it made its way over to Europe,

十年內，它就散播到了歐洲，

where eventually the great Charles Darwin got to study this plant,

最終偉大的達爾文 得以研究這種植物，

and this plant absolutely blew him away.

這植物完全讓他驚呆了。

He called it the most wonderful plant in the world.

他稱之為世界上最美妙的植物。

This is a plant that was an evolutionary wonder.

這種植物是演化上的奇蹟。

This is a plant that moves quickly,

這種植物動的速度很快，

which is rare,

這點很稀有，

and it's carnivorous, which is also rare.

且它是肉食性的，這點也很稀有。

And this is in the same plant.

同一種植物有兩種稀有特性。

But I'm here today to tell you

但今天，我要告訴各位，

that's not even the coolest thing about this plant.

這還不是這植物最酷的事。

The coolest thing is that the plant can count.

最酷的事是植物能計數。

So in order to show that,

要展現這一點，

we have to get some vocabulary out of the way.

我們得要先解決一些字彙的意思。

So I'm going to do what we do in the classroom with students.

我打算用我們在教室裡 教學生的方式。

We're going to do an experiment on electrophysiology,

我們要做一個電流生理學實驗，

which is the recording of the body's electrical signal,

也就是記錄身體的電訊號，

either coming from neurons or from muscles.

可能來自神經元或肌肉。

And I'm putting some electrodes here on my wrists.

我要在我的手腕貼上電極。

As I hook them up,

等我把它們弄好，

we're going to be able to see a signal

我們就會看到訊號

on the screen here.

出現在螢幕上。

And this signal may be familiar to you.

你可能覺得這訊號很熟悉。

It's called the EKG, or the electrocardiogram.

它叫 EKG，或心電圖。

And this is coming from neurons in my heart

這來自我心臟的神經元，

that are firing what's called action potentials,

這些神經元會發射所謂的動作電位，

potential meaning voltage and action meaning it moves quickly up and down,

電位就是電壓， 動作就表示它快速上下動。

which causes my heart to fire,

造成我的心臟反應，

which then causes the signal that you see here.

產生出你們在這裡看到的訊號。

And so I want you to remember the shape of what we'll be looking at right here,

請各位記住我們在這裡看到的形狀，

because this is going to be important.

這點之後會很重要。

This is a way that the brain encodes information

這是頭腦把資訊編碼成

in the form of an action potential.

動作電位的一種形式。

So now let's turn to some plants.

現在，我們來看一些植物。

So I'm going to first introduce you to the mimosa,

我要先向各位介紹含羞草，

not the drink, but the Mimosa pudica,

不是含羞草調酒，是含羞草植物，

and this is a plant that's found in Central America and South America,

在中美和南美可以找到這種植物，

and it has behaviors.

它是有行為的。

And the first behavior I'm going to show you

我要展示的第一個行為是，

is if I touch the leaves here,

當我觸碰葉子，

you get to see that the leaves tend to curl up.

你們可以看到葉子會縮起來。

And then the second behavior is,

第二個行為是，

if I tap the leaf,

如果我輕敲葉子，

the entire branch seems to fall down.

整個分枝都會向下倒。

So why does it do that?

它為什麼要這樣做？

It's not really known to science.

科學還沒有答案。

One of the reasons why could be that it scares away insects

原因之一可能是它想把昆蟲嚇跑，

or it looks less appealing to herbivores.

或比較不會吸引到食草動物。

But how does it do that? Now, that's interesting.

但它怎麼做到的？這就很有趣了。

We can do an experiment to find out.

我們可以做個實驗來找出答案。

So what we're going to do now,

我們現在要做的，

just like I recorded the electrical potential from my body,

就像是我記錄我身體的電位一樣，

we're going to record the electrical potential from this plant, this mimosa.

我們要記錄這含羞草的電位。

And so what we're going to do is I've got a wire wrapped around the stem,

我們要做的是， 用電線包住莖的部份，

and I've got the ground electrode where?

把接地電極接到哪裡呢？

In the ground. It's an electrical engineering joke. Alright.

地上。這是個電子工程師笑話。

(Laughter)

（笑聲）

Alright. So I'm going to go ahead and tap the leaf here,

好。我要輕敲這裡的葉子，

and I want you to look at the electrical recording

請各位注意看等下會出現

that we're going to see inside the plant.

來自植物的電訊號記錄。

Whoa. It is so big, I've got to scale it down.

哇。好大，我得要縮一下比例。

Alright. So what is that?

好了。那是什麼？

That is an action potential that is happening inside the plant.

那是行動電位， 且是在植物內部發生的。

Why was it happening?

它為什麼會發生？

Because it wanted to move. Right?

因為它想要動，對嗎？

And so when I hit the touch receptors,

所以當我去觸碰接收器，

it sent a voltage all the way down to the end of the stem,

它會發送電壓， 一路向下送到莖的底端，

which caused it to move.

使莖動了。

And now, in our arms, we would move our muscles,

在我們的手臂中，我們會動肌肉，

but the plant doesn't have muscles.

但植物沒有肌肉。

What it has is water inside the cells

它的細胞中有水份，

and when the voltage hits it, it opens up, releases the water,

當電壓接觸到它時， 它會打開，放出水份，

changes the shape of the cells, and the leaf falls.

改變細胞的形狀，葉子就會倒下。

OK. So here we see an action potential encoding information to move. Alright?

所以，在這裡我們看到了行動電位 能夠將資訊編碼來造成移動。對吧？

But can it do more?

但它能做更多嗎？

So let's go to find out.

我們來找出答案。

We're going to go to our good friend, the Venus flytrap here,

我們要來找我們這裡的 好朋友捕蠅草，

and we're going to take a look at what happens inside the leaf

我們要來看一下， 當一隻蒼蠅降落在這裡時，

when a fly lands on here.

葉子裡會發生什麼事。

So I'm going to pretend to be a fly right now.

現在，我要假裝是一隻蒼蠅。

And now here's my Venus flytrap,

我的捕蠅草在這裡，

and inside the leaf, you're going to notice

看一下葉子內部，

that there are three little hairs here, and those are trigger hairs.

有三根毛在這裡，它們是感覺毛。

And so when a fly lands --

所以當蒼蠅降落──

I'm going to touch one of the hairs right now.

我現在要來觸碰其中一根毛。

Ready? One, two, three.

準備好了嗎？一、二、三。

What do we get? We get a beautiful action potential.

我們得到了什麼？ 很漂亮的行動電位。

However, the flytrap doesn't close.

然而，捕蠅草沒有闔上。

And to understand why that is,

要了解為什麼會這樣，

we need to know a little bit more about the behavior of the flytrap.

我們需要多了解一點捕蠅草的行為。

Number one is that it takes a long time to open the traps back up --

第一，把陷阱重新打開 要花的時間很長──

you know, about 24 to 48 hours if there's no fly inside of it.

如果沒有蒼蠅在裡面的話， 大約要 24 到 48 小時。

And so it takes a lot of energy.

那要花很多的能量。

And two, it doesn't need to eat that many flies throughout the year.

第二，一整年間， 它並不需要吃那麼多蒼蠅。

Only a handful. It gets most of its energy from the sun.

少量即可。

它大部份的能量來自太陽。

It's just trying to replace some nutrients in the ground with flies.

它只是試著以蒼蠅 取代一些地面的營養物。

And the third thing is,

第三，

it only opens then closes the traps a handful of times

它只能將陷阱開闔少數幾次，

until that trap dies.

然後陷阱就會死亡。

So therefore, it wants to make really darn sure

因此，它要非常確定

that there's a meal inside of it before the flytrap snaps shut.

有餐點在陷阱裡面的時候， 它才會快速闔上。

So how does it do that?

它怎麼做到的？

It counts the number of seconds

它會計算秒數，

between successive touching of those hairs.

連續觸碰那些毛之間的時間間隔。

And so the idea is that there's a high probability,

概念是，如果裡面有蒼蠅，

if there's a fly inside of there, they're going to be quick together,

它就非常可能會闔上，

and so when it gets the first action potential,

所以當它接到第一個行動電位時，

它就開始計算，一、二，

it starts counting, one, two,

and if it gets to 20 and it doesn't fire again,

如果數到二十都不再有電位發出，

then it's not going to close,

它就不會闔上，

but if it does it within there, then the flytrap will close.

但如果有的話，捕蠅草就會闔上。

So we're going to go back now.

我們要再回來。

I'm going to touch the Venus flytrap again.

我要再次觸碰捕蠅草。

I've been talking for more than 20 seconds.

我已經講話超過二十秒了。

So we can see what happens when I touch the hair a second time.

來看看當我二度觸碰 這根毛時會發生什麼事。

So what do we get? We get a second action potential,

我們得到什麼？第二個行動電位，

but again, the leaf doesn't close.

但同樣的，葉子沒有闔上。

So now if I go back in there

如果我再回來，

and if I'm a fly moving around,

如果我是一隻到處跑的蒼蠅，

I'm going to be touching the leaf a few times.

就會再觸碰葉子幾次。

I'm going to go and brush it a few times.

我要再輕輕拂過它幾次。

And immediately,

馬上，

the flytrap closes.

捕蠅草闔上了。

So here we are seeing the flytrap actually doing a computation.

我們看到捕蠅草真的在計算。

It's determining if there's a fly inside the trap,

它判斷是否真的有蒼蠅在陷阱中，

and then it closes.

然後才闔上。

So let's go back to our original question.

所以，我們回到原先的問題。

Do plants have brains?

植物有頭腦嗎？

Well, the answer is no.

答案是沒有。

There's no brains in here.

這裡面沒有頭腦。

There's no axons, no neurons.

沒有軸突、沒有神經元。

It doesn't get depressed.

它不會沮喪。

It doesn't want to know what the Tigers' score is.

它不會想知道 底特律老虎隊目前得幾分。

It doesn't have self-actualization problems.

它沒有自我實現的問題。

But what it does have is something that's very similar to us,

但它有和我們很相似之處，

which is the ability to communicate using electricity.

就是用電來溝通的能力。

It just uses slightly different ions than we do,

只是它用的離子和我們有些微不同，

but it's actually doing the same thing.

但做的事是一樣的。

So just to show you

只是要讓大家看看

the ubiquitous nature of these action potentials,

這些行動電位無所不在的特性，

we saw it in the Venus flytrap,

我們在捕蠅草身上看到了，

we've seen an action potential in the mimosa.

我們在含羞草身上看到了。

We've even seen an action potential in a human.

我們在人類身上看到了。

Now, this is the euro of the brain.

這就是頭腦的歐元，

It's the way that all information is passed.

是讓所有資訊得以傳遞的方式。

And so what we can do is we can use those action potentials

我們能利用那些行動電位

to pass information

在不同種的植物之間

between species of plants.

傳遞資訊。

And so this is our interspecies plant-to-plant communicator,

這是我們的跨物種 植物對植物的溝通器，

and what we've done is we've created a brand new experiment

我們創造了一個全新的實驗，

where we're going to record the action potential from a Venus flytrap,

從捕蠅草這裡記錄行動電位，

and we're going to send it into the sensitive mimosa.

接著把它傳送給敏感的含羞草。

請各位回想一下，

So I want you to recall what happens

when we touch the leaves of the mimosa.

當我們觸碰含羞草葉面時 會發生什麼事。

It has touch receptors that are sending that information

它的觸碰接收器會向下傳送

back down in the form of an action potential.

行動電位形式的資訊。

And so what would happen

所以，若我們把捕蠅草的行動電位

if we took the action potential from the Venus flytrap

傳送到含羞草的莖內

and sent it into all the stems of the mimosa?

會發生什麼事？

We should be able to create the behavior of the mimosas

我們應該會在不用自己 觸碰含羞草的情況下

without actually touching it ourselves.

就引發含羞草的行為。

And so if you'll allow me,

所以，如果可以的話，

I'm going to go ahead and trigger this mimosa right now

我現在就要來觸碰捕蠅草的毛，

by touching on the hairs of the Venus flytrap.

來觸發含羞草的行為。

So we're going to send information about touch from one plant to another.

我們將會把觸碰一棵植物的資訊 傳送到另一棵植物。

So there you see it.

看到了嗎。

So --

所以，

(Applause)

（掌聲）

So I hope you learned a little bit, something about plants today,

我希望各位今天學到了 一點關於植物的知識，

and not only that.

且不只如此。

You learned that plants could be used to help teach neuroscience

你們學到了植物能被用來 協助教導神經科學，

and bring along the neurorevolution.

並能帶來神經革命。

Thank you.

謝謝。

(Applause)

（掌聲）