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TED2012

Carl Schoonover: How to look inside the brain

カール・シューノーヴァー: 脳の中身を見る方法

February 28, 2012

脳の研究における進歩には 目を見張るものがあるが、実際どうやって脳内のニューロンを調べるのか?神経科学者でTEDフェローのカール・シューノーヴァーが、魅力的な写真の数々を使いながら、脳の中身を見せてくれるツールを紹介します。

Carl Schoonover - Neuroscience PhD student + writer
Carl Schoonover is a neuroscientist and one of the founders of NeuWrite, a collaboration between writers and neuroscientist. Full bio

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Double-click the English subtitles below to play the video.
This is a thousand-year-old drawing of the brain.
これは千年前の脳のスケッチです
00:15
It's a diagram of the visual system.
視覚系を表す図で
00:19
And some things look very familiar today.
現代では見慣れたものも いくつかあります
00:21
Two eyes at the bottom, optic nerve flowing out from the back.
後部から伸びる視神経の先端に 目玉があります
00:24
There's a very large nose
大きな鼻がありますが
00:28
that doesn't seem to be connected to anything in particular.
特に何ともつながっていません
00:30
And if we compare this
この図を最近の
00:34
to more recent representations of the visual system,
視覚系の解説図と比べると
00:35
you'll see that things have gotten substantially more complicated
千年を経て物事が非常に
00:37
over the intervening thousand years.
複雑になったと分かります
00:40
And that's because today we can see what's inside of the brain,
脳の内側を見る事が
00:42
rather than just looking at its overall shape.
可能になったためです
00:45
Imagine you wanted to understand how a computer works
PCの仕組みを知りたいのに
00:47
and all you could see was a keyboard, a mouse, a screen.
見えるのはキーボード・マウス・画面だけ
00:51
You really would be kind of out of luck.
これではどうにもなりません
00:55
You want to be able to open it up, crack it open,
ふたを開けて
00:57
look at the wiring inside.
配線を見られたらいいのに
00:59
And up until a little more than a century ago,
百年ほど前までは
01:01
nobody was able to do that with the brain.
ふたを開けて 脳の
01:03
Nobody had had a glimpse of the brain's wiring.
配線を見るなんて不可能でした
01:05
And that's because if you take a brain out of the skull
脳を頭蓋骨から取り出し
01:07
and you cut a thin slice of it,
薄く切って
01:10
put it under even a very powerful microscope,
強力な顕微鏡で見ても
01:11
there's nothing there.
何も見えないのです
01:14
It's gray, formless.
灰色の混沌
01:15
There's no structure. It won't tell you anything.
構造が無いと何も分からない
01:17
And this all changed in the late 19th century.
しかし19世紀末に変化が起こります
01:19
Suddenly, new chemical stains for brain tissue were developed
脳細胞用の化学染色材が開発され
01:22
and they gave us our first glimpses at brain wiring.
脳の配線が見られるようになりました
01:26
The computer was cracked open.
PCのふたが開いたのです
01:29
So what really launched modern neuroscience
現代神経科学の夜明けは
01:31
was a stain called the Golgi stain.
ゴルジ染料がもたらしました
01:34
And it works in a very particular way.
その原理はと言うと
01:35
Instead of staining all of the cells inside of a tissue,
組織内の全細胞でなく
01:37
it somehow only stains about one percent of them.
1%だけを染色します
01:40
It clears the forest, reveals the trees inside.
すると 森が消え 中から木が姿を現します
01:44
If everything had been labeled, nothing would have been visible.
全体から区別する事で
01:47
So somehow it shows what's there.
そこに何があるのか見えるのです
01:50
Spanish neuroanatomist Santiago Ramon y Cajal,
現代神経科学の祖として名高い
01:52
who's widely considered the father of modern neuroscience,
神経解剖学者 ラモン・イ・カハールは
01:54
applied this Golgi stain, which yields data which looks like this,
ゴルジ染色を使い このようなデータを得て
01:57
and really gave us the modern notion of the nerve cell, the neuron.
神経細胞ニューロンの解明に寄与しました
02:01
And if you're thinking of the brain as a computer,
脳をコンピュータに例えると
02:05
this is the transistor.
これはトランジスタです
02:07
And very quickly Cajal realized
カハールはすぐに気がつきました
02:09
that neurons don't operate alone,
ニューロンは単体では機能せず
02:11
but rather make connections with others
他の物質とつながって
02:14
that form circuits just like in a computer.
コンピュータ内の回路の様なものを形成するのだと
02:16
Today, a century later, when researchers want to visualize neurons,
百年後の今 ニューロンの可視化には
02:18
they light them up from the inside rather than darkening them.
染色よりも発光が使われます
02:22
And there's several ways of doing this.
複数の手法がありますが
02:24
But one of the most popular ones
最もよく使われるのは
02:25
involves green fluorescent protein.
緑色蛍光タンパク質(GFP)です
02:27
Now green fluorescent protein,
このGFPという物質は
02:29
which oddly enough comes from a bioluminescent jellyfish,
なんと発光クラゲから採取でき
02:31
is very useful.
至極便利です
02:34
Because if you can get the gene for green fluorescent protein
GFPの遺伝子を取り出し
02:35
and deliver it to a cell,
細胞に注入すると
02:38
that cell will glow green --
その細胞は緑色に発光します
02:40
or any of the many variants now of green fluorescent protein,
GFPには様々な種類があり
02:41
you get a cell to glow many different colors.
細胞を色分けし発光させることが出来ます
02:45
And so coming back to the brain,
脳の話に戻りましょう
02:47
this is from a genetically engineered mouse called "Brainbow."
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
02:48
And it's so called, of course,
そう呼ばれるのは
02:52
because all of these neurons are glowing different colors.
ニューロンが虹のように見えるからです
02:54
Now sometimes neuroscientists need to identify
神経科学者は時に
02:57
individual molecular components of neurons, molecules,
細胞全体ではなく ニューロンの分子成分を
03:01
rather than the entire cell.
特定せねばなりません
03:04
And there's several ways of doing this,
複数の手法がありますが
03:06
but one of the most popular ones
最もよく使われるのは
03:07
involves using antibodies.
抗体を使うものです
03:09
And you're familiar, of course,
ご存知の通り抗体は
03:11
with antibodies as the henchmen of the immune system.
免疫システムの忠実な下僕ですが
03:12
But it turns out that they're so useful to the immune system
他にも便利な事が分かりました
03:15
because they can recognize specific molecules,
特定の分子を認識できるのです
03:18
like, for example, the code protein
体内に侵入するウイルスの
03:20
of a virus that's invading the body.
固有の蛋白質などです
03:22
And researchers have used this fact
研究者はこれを
03:25
in order to recognize specific molecules inside of the brain,
脳内の特定分子の認識に使います
03:27
recognize specific substructures of the cell
細胞の特定基礎構造を認識し
03:31
and identify them individually.
個別に特定するのです
03:34
And a lot of the images I've been showing you here are very beautiful,
ここでお見せしている写真はどれも美しく
03:36
but they're also very powerful.
同時に非常に力強く
03:39
They have great explanatory power.
説明力があります
03:41
This, for example, is an antibody staining
例えばこれはネズミの脳の
03:42
against serotonin transporters in a slice of mouse brain.
セロトニン伝達物質を抗体染色したものです
03:45
And you've heard of serotonin, of course,
セロトニンは
03:48
in the context of diseases like depression and anxiety.
鬱や不安神経症の解説に使われます
03:50
You've heard of SSRIs,
SSRI は
03:53
which are drugs that are used to treat these diseases.
これらの病気のための薬で
03:54
And in order to understand how serotonin works,
セロトニンがどう作用するのかは
03:57
it's critical to understand where the serontonin machinery is.
その分泌元を突き止めねばならず
04:00
And antibody stainings like this one
こういった抗体染色は
04:03
can be used to understand that sort of question.
この質問を理解するのに役立ちます
04:04
I'd like to leave you with the following thought:
最後にお話ししたいのが
04:08
Green fluorescent protein and antibodies
GFPと抗体は どちらも
04:11
are both totally natural products at the get-go.
全くの天然物質です
04:13
They were evolved by nature
自然がこれらを進化させた目的は
04:16
in order to get a jellyfish to glow green for whatever reason,
クラゲを緑に発光させたり
04:19
or in order to detect the code protein of an invading virus, for example.
侵入ウィルスの固有の蛋白質を検出するためでした
04:22
And only much later did scientists come onto the scene
ずっと後になって やっと科学者が現れ
04:26
and say, "Hey, these are tools,
「おい これは使えるぞ」
04:29
these are functions that we could use
「この機能は俺たちの研究にぴったりだ」
04:31
in our own research tool palette."
と言うのです
04:33
And instead of applying feeble human minds
貧弱な人類の頭で
04:35
to designing these tools from scratch,
これらのツールを作り出す代わりに
04:39
there were these ready-made solutions right out there in nature
何百万年もの年月をかけ着々と
04:41
developed and refined steadily for millions of years
解決策を用意してくれていたのは
04:44
by the greatest engineer of all.
自然という偉大な技術者なのです
04:47
Thank you.
ありがとうございました
04:48
(Applause)
(拍手)
04:50
Translator:Mizuki Anzai
Reviewer:Akiko Hicks

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Carl Schoonover - Neuroscience PhD student + writer
Carl Schoonover is a neuroscientist and one of the founders of NeuWrite, a collaboration between writers and neuroscientist.

Why you should listen

Carl is a neuroscience PhD candidate at Columbia University, where he works on microanatomy and electrophysiology of rodent somatosensory cortex. He the author of Portraits of the Mind: Visualizing the Brain from Antiquity to the 21st Century, and has written for the New York Times, Le Figaro, the Huffington Post, Science, Scientific American, Design Observer, and Boing Boing. In 2008 he cofounded NeuWrite, a collaborative working group for scientists, writers, and those in between. He hosts a radio show on WkCR 89.9FM, which focuses on opera and classical music, and their relationship to the brain.

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