It's a diagram of the visual system.

これは千年前の脳のスケッチです

And some things look very familiar today.

視覚系を表す図で

Two eyes at the bottom, optic nerve flowing out from the back.

現代では見慣れたものも いくつかあります

There's a very large nose

後部から伸びる視神経の先端に 目玉があります

that doesn't seem to be connected to anything in particular.

大きな鼻がありますが

And if we compare this

特に何ともつながっていません

to more recent representations of the visual system,

この図を最近の

you'll see that things have gotten substantially more complicated

視覚系の解説図と比べると

over the intervening thousand years.

千年を経て物事が非常に

And that's because today we can see what's inside of the brain,

複雑になったと分かります

rather than just looking at its overall shape.

脳の内側を見る事が

Imagine you wanted to understand how a computer works

可能になったためです

and all you could see was a keyboard, a mouse, a screen.

PCの仕組みを知りたいのに

You really would be kind of out of luck.

見えるのはキーボード・マウス・画面だけ

You want to be able to open it up, crack it open,

これではどうにもなりません

look at the wiring inside.

ふたを開けて

And up until a little more than a century ago,

配線を見られたらいいのに

nobody was able to do that with the brain.

百年ほど前までは

Nobody had had a glimpse of the brain's wiring.

ふたを開けて 脳の

And that's because if you take a brain out of the skull

配線を見るなんて不可能でした

and you cut a thin slice of it,

脳を頭蓋骨から取り出し

put it under even a very powerful microscope,

薄く切って

there's nothing there.

強力な顕微鏡で見ても

It's gray, formless.

何も見えないのです

There's no structure. It won't tell you anything.

灰色の混沌

And this all changed in the late 19th century.

構造が無いと何も分からない

Suddenly, new chemical stains for brain tissue were developed

しかし19世紀末に変化が起こります

and they gave us our first glimpses at brain wiring.

脳細胞用の化学染色材が開発され

The computer was cracked open.

脳の配線が見られるようになりました

So what really launched modern neuroscience

PCのふたが開いたのです

was a stain called the Golgi stain.

現代神経科学の夜明けは

And it works in a very particular way.

ゴルジ染料がもたらしました

Instead of staining all of the cells inside of a tissue,

その原理はと言うと

it somehow only stains about one percent of them.

組織内の全細胞でなく

It clears the forest, reveals the trees inside.

1％だけを染色します

If everything had been labeled, nothing would have been visible.

すると 森が消え 中から木が姿を現します

So somehow it shows what's there.

全体から区別する事で

Spanish neuroanatomist Santiago Ramon y Cajal,

そこに何があるのか見えるのです

who's widely considered the father of modern neuroscience,

現代神経科学の祖として名高い

applied this Golgi stain, which yields data which looks like this,

神経解剖学者 ラモン・イ・カハールは

and really gave us the modern notion of the nerve cell, the neuron.

ゴルジ染色を使い このようなデータを得て

And if you're thinking of the brain as a computer,

神経細胞ニューロンの解明に寄与しました

this is the transistor.

脳をコンピュータに例えると

And very quickly Cajal realized

これはトランジスタです

that neurons don't operate alone,

カハールはすぐに気がつきました

but rather make connections with others

ニューロンは単体では機能せず

that form circuits just like in a computer.

他の物質とつながって

Today, a century later, when researchers want to visualize neurons,

コンピュータ内の回路の様なものを形成するのだと

they light them up from the inside rather than darkening them.

百年後の今 ニューロンの可視化には

And there's several ways of doing this.

染色よりも発光が使われます

But one of the most popular ones

複数の手法がありますが

involves green fluorescent protein.

最もよく使われるのは

Now green fluorescent protein,

緑色蛍光タンパク質（GFP）です

which oddly enough comes from a bioluminescent jellyfish,

このGFPという物質は

is very useful.

なんと発光クラゲから採取でき

Because if you can get the gene for green fluorescent protein

至極便利です

and deliver it to a cell,

GFPの遺伝子を取り出し

that cell will glow green --

細胞に注入すると

or any of the many variants now of green fluorescent protein,

その細胞は緑色に発光します

you get a cell to glow many different colors.

GFPには様々な種類があり

And so coming back to the brain,

細胞を色分けし発光させることが出来ます

this is from a genetically engineered mouse called "Brainbow."

脳の話に戻りましょう

And it's so called, of course,

これは「ブレインボー」という 遺伝子操作したネズミから 採取しました

because all of these neurons are glowing different colors.

そう呼ばれるのは

Now sometimes neuroscientists need to identify

ニューロンが虹のように見えるからです

individual molecular components of neurons, molecules,

神経科学者は時に

rather than the entire cell.

細胞全体ではなく ニューロンの分子成分を

And there's several ways of doing this,

特定せねばなりません

but one of the most popular ones

複数の手法がありますが

involves using antibodies.

最もよく使われるのは

And you're familiar, of course,

抗体を使うものです

with antibodies as the henchmen of the immune system.

ご存知の通り抗体は

But it turns out that they're so useful to the immune system

免疫システムの忠実な下僕ですが

because they can recognize specific molecules,

他にも便利な事が分かりました

like, for example, the coat protein

特定の分子を認識できるのです

of a virus that's invading the body.

体内に侵入するウイルスの

And researchers have used this fact

固有の蛋白質などです

in order to recognize specific molecules inside of the brain,

研究者はこれを

recognize specific substructures of the cell

脳内の特定分子の認識に使います

and identify them individually.

細胞の特定基礎構造を認識し

And a lot of the images I've been showing you here are very beautiful,

個別に特定するのです

but they're also very powerful.

ここでお見せしている写真はどれも美しく

They have great explanatory power.

同時に非常に力強く

This, for example, is an antibody staining

説明力があります

against serotonin transporters in a slice of mouse brain.

例えばこれはネズミの脳の

And you've heard of serotonin, of course,

セロトニン伝達物質を抗体染色したものです

in the context of diseases like depression and anxiety.

セロトニンは

You've heard of SSRIs,

鬱や不安神経症の解説に使われます

which are drugs that are used to treat these diseases.

SSRI は

And in order to understand how serotonin works,

これらの病気のための薬で

it's critical to understand where the serontonin machinery is.

セロトニンがどう作用するのかは

And antibody stainings like this one

その分泌元を突き止めねばならず

can be used to understand that sort of question.

こういった抗体染色は

I'd like to leave you with the following thought:

この質問を理解するのに役立ちます

Green fluorescent protein and antibodies

最後にお話ししたいのが

are both totally natural products at the get-go.

GFPと抗体は どちらも

They were evolved by nature

全くの天然物質です

in order to get a jellyfish to glow green for whatever reason,

自然がこれらを進化させた目的は

or in order to detect the coat protein of an invading virus, for example.

クラゲを緑に発光させたり

And only much later did scientists come onto the scene

侵入ウィルスの固有の蛋白質を検出するためでした

and say, "Hey, these are tools,

ずっと後になって やっと科学者が現れ

these are functions that we could use

「おい これは使えるぞ」

in our own research tool palette."

「この機能は俺たちの研究にぴったりだ」

And instead of applying feeble human minds

と言うのです

to designing these tools from scratch,

貧弱な人類の頭で

there were these ready-made solutions right out there in nature

これらのツールを作り出す代わりに

developed and refined steadily for millions of years

何百万年もの年月をかけ着々と

by the greatest engineer of all.

解決策を用意してくれていたのは

Thank you.

自然という偉大な技術者なのです

(Applause)

ありがとうございました