Michael Dickinson: How a fly flies

313,613 views ・ 2013-02-22

TED


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00:00
Translator: Joseph Geni Reviewer: Morton Bast
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譯者: Joan Liu 審譯者: Hao-Wei Chang
00:15
I grew up watching Star Trek. I love Star Trek.
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我看著《星際爭霸戰》長大。 我超愛《星際爭霸戰》。
00:19
Star Trek made me want to see alien creatures,
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《星際爭霸戰》讓我想要看外星生物,
00:23
creatures from a far-distant world.
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從遙遠星球來的生物。
00:26
But basically, I figured out that I could find
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但事實上,我發現我可以在地球上
00:28
those alien creatures right on Earth.
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找到這些外星生物。
00:31
And what I do is I study insects.
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我所作的就是研究昆蟲。
00:34
I'm obsessed with insects, particularly insect flight.
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我迷上了昆蟲, 尤其是昆蟲飛行。
00:37
I think the evolution of insect flight is perhaps
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我認為昆蟲飛行的演化
00:40
one of the most important events in the history of life.
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大概是生命史上最重要的事。
00:43
Without insects, there'd be no flowering plants.
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如果沒有昆蟲, 就不會有開花植物。
00:45
Without flowering plants, there would be no
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沒有開花植物, 就不會有聰明、
00:47
clever, fruit-eating primates giving TED Talks.
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吃水果的靈長類在TED演講。
00:50
(Laughter)
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(笑聲)
00:53
Now,
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現在,
00:55
David and Hidehiko and Ketaki
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大衛、希地可和科踏希
00:58
gave a very compelling story about
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說了一個很令人信服的故事,
01:01
the similarities between fruit flies and humans,
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故事關於果蠅與人的相似處。
01:04
and there are many similarities,
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我們真的有許多相似之處,
01:06
and so you might think that if humans are similar to fruit flies,
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所以你也許會認為 如果人跟果蠅是相似的,
01:09
the favorite behavior of a fruit fly might be this, for example --
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那麼果蠅最喜歡的行為可能是這個
01:12
(Laughter)
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(笑聲)
01:15
but in my talk, I don't want to emphasize on the similarities
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但在我的演講中, 我不想強調果蠅與人的相似之處,
01:18
between humans and fruit flies, but rather the differences,
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我反而要談兩者間不同的部份,
01:21
and focus on the behaviors that I think fruit flies excel at doing.
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而且我要強調果蠅擅長的行為。
01:26
And so I want to show you a high-speed video sequence
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所以我想要給你們看一段高速影片,
01:29
of a fly shot at 7,000 frames per second in infrared lighting,
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是在紅外光照明下 以每秒 7 千幅拍攝果蠅飛行的影片,
01:33
and to the right, off-screen, is an electronic looming predator
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在右邊螢幕外, 有個電子虛擬獵食者
01:37
that is going to go at the fly.
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會飛去捕食果蠅。
01:39
The fly is going to sense this predator.
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果蠅會感受到這個獵食者。
01:40
It is going to extend its legs out.
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牠會伸長它的腿。
01:43
It's going to sashay away
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牠會以搖曳生姿飛走
01:44
to live to fly another day.
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然後多活一天。
01:47
Now I have carefully cropped this sequence
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我仔細裁剪了這個影片
01:49
to be exactly the duration of a human eye blink,
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讓他的速度跟 人類眨眼速度一樣,
01:53
so in the time that it would take you to blink your eye,
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所以在你眨眼所需要的時間中,
01:55
the fly has seen this looming predator,
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果蠅會看到這個獵食者、
01:59
estimated its position, initiated a motor pattern to fly it away,
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估計位置、開始運動並飛走,
02:05
beating its wings at 220 times a second as it does so.
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以每秒拍動翅膀 220 次的速度飛走。
02:09
I think this is a fascinating behavior
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我認為這是一個令人著迷的行為,
02:11
that shows how fast the fly's brain can process information.
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這表示果蠅的大腦 可以如此快速地處理資訊。
02:15
Now, flight -- what does it take to fly?
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飛行需要什麼?
02:18
Well, in order to fly, just as in a human aircraft,
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嗯,要能夠飛翔, 就得像人類的飛機一樣,
02:21
you need wings that can generate sufficient aerodynamic forces,
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你需要可以產生 足夠空氣動力的翅膀,
02:24
you need an engine sufficient to generate the power required for flight,
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你需要能夠產生 足夠飛行所需能量的發動機,
02:27
and you need a controller,
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且你需要一個控制器。
02:29
and in the first human aircraft, the controller was basically
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在人類第一架飛機上,控制器基本上是
02:32
the brain of Orville and Wilbur sitting in the cockpit.
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坐在駕駛艙的奧維爾和威爾伯的大腦。
02:36
Now, how does this compare to a fly?
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這跟果蠅比較起來是如何呢?
02:39
Well, I spent a lot of my early career trying to figure out
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嗯,我早期的研究 花了很多時間試圖找出
02:42
how insect wings generate enough force to keep the flies in the air.
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昆蟲翅膀如何生成 足夠的能量使果蠅得以維持在空中。
02:46
And you might have heard how engineers proved
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你也許聽說過工程師如何證明
02:48
that bumblebees couldn't fly.
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熊蜂飛不起來。
02:50
Well, the problem was in thinking that the insect wings
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嗯,這個思考邏輯的問題是
02:53
function in the way that aircraft wings work. But they don't.
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認為兩者翅膀的運作方式一樣。 但事實上不然。
02:56
And we tackle this problem by building giant,
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我們研究的方法是建造巨大模型,
02:59
dynamically scaled model robot insects
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按動態比例建造巨大機器昆蟲
03:02
that would flap in giant pools of mineral oil
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並在礦物油巨型池當中拍打翅膀,
03:06
where we could study the aerodynamic forces.
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這樣我們可以研究空氣動力。
03:08
And it turns out that the insects flap their wings
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我們發現昆蟲以 一種非常聰明的方法拍動翅膀,
03:10
in a very clever way, at a very high angle of attack
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有非常大的攻角,
03:13
that creates a structure at the leading edge of the wing,
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使翅膀前沿產生一個像龍捲風的結構
03:16
a little tornado-like structure called a leading edge vortex,
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叫作前緣渦,
03:19
and it's that vortex that actually enables the wings
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而且正是這個翅膀上的前緣渦
03:22
to make enough force for the animal to stay in the air.
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讓動物能夠產生足以停留在空中的動力。
03:25
But the thing that's actually most -- so, what's fascinating
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但是實際上迷人的
03:28
is not so much that the wing has some interesting morphology.
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並不是這個構造有多稀奇。
03:31
What's clever is the way the fly flaps it,
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而是聰明的果蠅如何拍打它,
03:34
which of course ultimately is controlled by the nervous system,
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這當然最終是 受中樞神經系統控制,
03:38
and this is what enables flies to perform
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而這也是果蠅可以執行
03:40
these remarkable aerial maneuvers.
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這些高超飛行技巧的原因。
03:43
Now, what about the engine?
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那麼引擎呢?
03:45
The engine of the fly is absolutely fascinating.
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果蠅的引擎絕對令人著迷。
03:48
They have two types of flight muscle:
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牠們有兩種類型的飛行肌:
03:50
so-called power muscle, which is stretch-activated,
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所謂的能量肌肉,這是牽張啟動,
03:53
which means that it activates itself and does not need to be controlled
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也就是說它可以自我啟動
03:56
on a contraction-by-contraction basis by the nervous system.
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不需要中樞神經 不斷收縮來控制。
04:00
It's specialized to generate the enormous power required for flight,
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這是由飛行所需 巨大的力量所專一化出來的,
04:04
and it fills the middle portion of the fly,
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這肌肉充滿了果蠅中間的部分,
04:06
so when a fly hits your windshield,
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所以當一隻果蠅撞到你的擋風玻璃時,
04:08
it's basically the power muscle that you're looking at.
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基本上你看到的 就是這些能量肌肉的動作。
04:10
But attached to the base of the wing
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但在機翼的基部
04:12
is a set of little, tiny control muscles
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有一套小小的微型控制肌肉,
04:15
that are not very powerful at all, but they're very fast,
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它們不大有力但速度非常快,
04:18
and they're able to reconfigure the hinge of the wing
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它們能夠以每一拍擊為基礎
04:22
on a stroke-by-stroke basis,
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重新配置機翼轉軸,
04:23
and this is what enables the fly to change its wing
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這使果蠅得以調整翅膀
04:26
and generate the changes in aerodynamic forces
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來產生及更改空氣動力,
04:29
which change its flight trajectory.
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並連帶改變其飛行軌跡。
04:32
And of course, the role of the nervous system is to control all this.
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當然,中樞神經系統控制這一切。
04:36
So let's look at the controller.
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所以讓我們來看看控制器。
04:37
Now flies excel in the sorts of sensors
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果蠅在這方面
04:40
that they carry to this problem.
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有各種非常精巧的感應器。
04:42
They have antennae that sense odors and detect wind detection.
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牠們有天線可以感受氣味和風向。
04:46
They have a sophisticated eye which is
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牠們有複雜的眼睛,
04:48
the fastest visual system on the planet.
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是這個星球上最快的視覺系統。
04:50
They have another set of eyes on the top of their head.
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牠們在頭頂上有另一對眼睛,
04:52
We have no idea what they do.
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但目前我們還不清楚它們的用處。
04:54
They have sensors on their wing.
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牠們的翅膀上有感應器。
04:57
Their wing is covered with sensors, including sensors
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牠們的翅耪上充滿了感應器,
05:01
that sense deformation of the wing.
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包括感應機翼變形的感應器。
05:03
They can even taste with their wings.
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牠們甚至可以 用翅膀偵測味道。
05:05
One of the most sophisticated sensors a fly has
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果蠅最複雜的感應器之一
05:08
is a structure called the halteres.
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是一種被稱為「平衡棒」的構造。
05:10
The halteres are actually gyroscopes.
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平衡棒其實就是陀螺儀。
05:11
These devices beat back and forth about 200 hertz during flight,
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這個構造在飛行時 大約以 200 赫茲的速度擺動
05:16
and the animal can use them to sense its body rotation
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使動物可以用它們偵測身體旋轉,
05:19
and initiate very, very fast corrective maneuvers.
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並啟動非常、非常快速地糾正動作。
05:23
But all of this sensory information has to be processed
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但所有感官資訊 都需要經由大腦處理,
05:25
by a brain, and yes, indeed, flies have a brain,
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是的,果蠅有大腦的,
05:29
a brain of about 100,000 neurons.
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一個大約有 10 萬神經元的大腦。
05:32
Now several people at this conference
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已經有一些人在這次會議中
05:34
have already suggested that fruit flies could serve neuroscience
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提出果蠅可以作為神經科學的模型,
05:39
because they're a simple model of brain function.
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因為牠們具有簡單的大腦。
05:42
And the basic punchline of my talk is,
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然後我的演講的結語會是:
05:44
I'd like to turn that over on its head.
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我想要直接反駁它。
05:47
I don't think they're a simple model of anything.
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我不認為牠們是任何東西的簡單模型。
05:49
And I think that flies are a great model.
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我認為果蠅是一個偉大的模型。
05:52
They're a great model for flies.
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牠們是為飛行而生的偉大模型。
05:54
(Laughter)
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(笑聲)
05:57
And let's explore this notion of simplicity.
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且讓我們研究一下這種簡單的想法。
06:00
So I think, unfortunately, a lot of neuroscientists,
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所以我認為很多的神經學家
06:02
we're all somewhat narcissistic.
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都不幸地有些自戀。
06:04
When we think of brain, we of course imagine our own brain.
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當我們想到大腦時, 我們當然想自己的大腦。
06:08
But remember that this kind of brain,
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但請記住這種腦,
06:09
which is much, much smaller
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體積小很多很多的腦
06:11
— instead of 100 billion neurons, it has 100,000 neurons —
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— 它沒有 1 千億神經元,它只有 1 萬神經元 —
06:14
but this is the most common form of brain on the planet
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但這是這個星球上最常見的大腦形式
06:17
and has been for 400 million years.
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而且已經存在 4 億年了。
06:20
And is it fair to say that it's simple?
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說它簡單公平嗎?
06:22
Well, it's simple in the sense that it has fewer neurons,
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嗯,以神經元數量來說是簡單的,
06:24
but is that a fair metric?
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但這是一個公平的指標嗎?
06:26
And I would propose it's not a fair metric.
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我認為這不是一個公平的指標。
06:28
So let's sort of think about this. I think we have to compare --
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讓我們來想一想。 我們必須進行比較 ——
06:31
(Laughter) —
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(笑聲) ——
06:33
we have to compare the size of the brain
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我們要比較大腦大小
06:38
with what the brain can do.
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與大腦可以做什麼。
06:40
So I propose we have a Trump number,
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假設我們有王牌數,
06:43
and the Trump number is the ratio of this man's
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王牌數是這個男人可以做的事
06:46
behavioral repertoire to the number of neurons in his brain.
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跟大腦中神經元數目的比值。
06:49
We'll calculate the Trump number for the fruit fly.
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我們也可以計算出果蠅的王牌號。
06:52
Now, how many people here think the Trump number
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現在,有多少人在這裡覺得果蠅的
06:55
is higher for the fruit fly?
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王牌數會比較高?
06:57
(Applause)
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(掌聲)
07:00
It's a very smart, smart audience.
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真是很聰明、很聰明的觀眾。
07:03
Yes, the inequality goes in this direction, or I would posit it.
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雖然這比較不完全恰當, 但至少我認為是這樣的。
07:06
Now I realize that it is a little bit absurd
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好,我知道比較人和果蠅的行為
07:09
to compare the behavioral repertoire of a human to a fly.
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是有點荒謬。
07:12
But let's take another animal just as an example. Here's a mouse.
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但讓我們看另一種動物:一隻小鼠。
07:16
A mouse has about 1,000 times as many neurons as a fly.
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一隻小鼠的神經元數目大約是果蠅的 1 千倍。
07:21
I used to study mice. When I studied mice,
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我以前研究過小鼠。 當我還在研究小鼠時,
07:23
I used to talk really slowly.
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我講話速度慢很多。
07:26
And then something happened when I started to work on flies.
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這在當我開始研究果蠅時產生了變化。
07:28
(Laughter)
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(笑聲)
07:31
And I think if you compare the natural history of flies and mice,
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我覺得如果你比較果蠅和小鼠的自然史,
07:34
it's really comparable. They have to forage for food.
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它們是可比的。 牠們都要覓食。
07:37
They have to engage in courtship.
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牠們都要求愛。
07:40
They have sex. They hide from predators.
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牠們都會發生性關係。 牠們都要躲避獵食者。
07:43
They do a lot of the similar things.
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牠們做很多類似的事情。
07:45
But I would argue that flies do more.
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但我想說果蠅做更多。
07:47
So for example, I'm going to show you a sequence,
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例如,我要給你們看一段影片,
07:50
and I have to say, some of my funding comes from the military,
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我不得不說, 我的一些資金來源來自軍方,
07:55
so I'm showing this classified sequence
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所以,我給你們這部機密影片,
07:57
and you cannot discuss it outside of this room. Okay?
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請你們離開這裡後必須絕口不提。好嗎?
08:01
So I want you to look at the payload
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所以想要你們看看果蠅尾巴
08:03
at the tail of the fruit fly.
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的有效載荷。
08:06
Watch it very closely,
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仔細看,
08:08
and you'll see why my six-year-old son
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你們會懂為什麼我的六歲兒子
08:12
now wants to be a neuroscientist.
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現在想要成為一個神經學家。
08:17
Wait for it.
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等一下。
08:18
Pshhew.
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噓。
08:20
So at least you'll admit that if fruit flies are not as clever as mice,
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所以至少你們得承認, 如果果蠅沒有小鼠聰明,
08:23
they're at least as clever as pigeons. (Laughter)
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牠們至少達到鴿子的等級。 (笑聲)
08:28
Now, I want to get across that it's not just a matter of numbers
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現在,我想要傳達的不只是數字,
08:32
but also the challenge for a fly to compute
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還有果蠅大腦要用少量神經元
08:34
everything its brain has to compute with such tiny neurons.
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計算這所有資訊所面臨的挑戰。
08:37
So this is a beautiful image of a visual interneuron from a mouse
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這是小鼠視覺中間神經元的美麗影像,
08:40
that came from Jeff Lichtman's lab,
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這來自傑夫·歷之曼的實驗室,
08:43
and you can see the wonderful images of brains
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你們可以看到他在他的演講中
08:46
that he showed in his talk.
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使用的精彩大腦影像。
08:49
But up in the corner, in the right corner, you'll see,
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在右上角你們將看到,
08:52
at the same scale, a visual interneuron from a fly.
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在同樣的比例之下 一隻果蠅的視覺中間神經元。
08:56
And I'll expand this up.
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我把這展開。
08:58
And it's a beautifully complex neuron.
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它是一個精美複雜的神經元。
09:00
It's just very, very tiny, and there's lots of biophysical challenges
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它真是非常、 非常地小, 這必須克服許多生物物理的挑戰,
09:03
with trying to compute information with tiny, tiny neurons.
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才能用極為微小的神經元來計算資訊。
09:07
How small can neurons get? Well, look at this interesting insect.
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神經元能有多小? 那麼,讓我們看看這個有趣的昆蟲。
09:10
It looks sort of like a fly. It has wings, it has eyes,
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牠看起來有點像果蠅。牠有翅膀,牠有眼睛,
09:13
it has antennae, its legs, complicated life history,
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牠有天線,牠有腿, 也有複雜的生活史。
09:15
it's a parasite, it has to fly around and find caterpillars
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牠是一種寄生蟲, 牠要到處飛,並尋找毛毛蟲
09:18
to parasatize,
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當作寄主,
09:20
but not only is its brain the size of a salt grain,
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牠的大腦很小,
09:24
which is comparable for a fruit fly,
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跟果蠅可相比較,
09:26
it is the size of a salt grain.
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它也只有鹽粒大小。
09:29
So here's some other organisms at the similar scale.
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所以這裡是一些其它類似規模的物種。
09:32
This animal is the size of a paramecium and an amoeba,
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這個動物是草履蟲和變形蟲大小,
09:37
and it has a brain of 7,000 neurons that's so small --
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牠的大腦大約有 7 千神經元 —
09:40
you know these things called cell bodies you've been hearing about,
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你知道有種叫做細胞體的東西,
09:43
where the nucleus of the neuron is?
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就是神經元的細胞核所在的地方?
09:45
This animal gets rid of them because they take up too much space.
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這種動物沒有細胞體, 因為它們太佔空間了。
09:48
So this is a session on frontiers in neuroscience.
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這是神經科學研究的新領域。
09:51
I would posit that one frontier in neuroscience is to figure out how the brain of that thing works.
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我認為神經科學其中 一個新領域就是要研究這類大腦的運作。
09:56
But let's think about this. How can you make a small number of neurons do a lot?
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但讓我們想一想。 如何讓少量的神經元做很多事?
10:02
And I think, from an engineering perspective,
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我認為,從工程的角度看,
10:04
you think of multiplexing.
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要多功能。
10:06
You can take a hardware and have that hardware
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你們可以拿一個硬體,並用該硬體
10:08
do different things at different times,
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在不同的時間做不同的事情
10:10
or have different parts of the hardware doing different things.
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或用不同部分的硬體做不同的事情。
10:13
And these are the two concepts I'd like to explore.
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這些是我想要探討的兩個概念。
10:16
And they're not concepts that I've come up with,
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但不是我想出來的概念,
10:18
but concepts that have been proposed by others in the past.
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而是過去由其他人提出的概念。
10:23
And one idea comes from lessons from chewing crabs.
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一個想法是來自於咀嚼螃蟹的經驗。
10:26
And I don't mean chewing the crabs.
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我不是指吃螃蟹。
10:27
I grew up in Baltimore, and I chew crabs very, very well.
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我在巴爾的摩長大, 我非常、非常會吃螃蟹。
10:31
But I'm talking about the crabs actually doing the chewing.
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但我說的螃蟹的咀嚼。
10:34
Crab chewing is actually really fascinating.
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螃蟹的咀嚼實在令人著迷。
10:36
Crabs have this complicated structure under their carapace
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螃蟹在其甲殼下有個複雜的結構
10:39
called the gastric mill
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叫作胃磨機,
10:41
that grinds their food in a variety of different ways.
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以各種不同方式磨牠們的食物。
10:43
And here's an endoscopic movie of this structure.
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而這是內鏡下看到的這種結構的影片。
10:48
The amazing thing about this is that it's controlled
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令人驚訝的是它是由一組非常小的神經元控制,
10:51
by a really tiny set of neurons, about two dozen neurons
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約有 20 多個神經元可以
10:54
that can produce a vast variety of different motor patterns,
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產生多種不同的運動模式,
10:59
and the reason it can do this is that this little tiny ganglion
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它可以這樣做的原因 是這個螃蟹身上的小小神經節
11:04
in the crab is actually inundated by many, many neuromodulators.
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實際上是被許多 神經調節物質所包圍。
11:08
You heard about neuromodulators earlier.
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你們剛剛已經聽過神經調節物質了。
11:10
There are more neuromodulators
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這個結構中可以改變、支配神經元的
11:12
that alter, that innervate this structure than actually neurons in the structure,
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神經調節物質比 構造中的神經元還多,
11:18
and they're able to generate a complicated set of patterns.
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且它們能夠生成複雜的模式。
11:22
And this is the work by Eve Marder and her many colleagues
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這是由伊娃·碼德和 她許多同事們的研究,
11:25
who've been studying this fascinating system
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他們研究這個有趣的系統,
11:28
that show how a smaller cluster of neurons
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可以說明一小群神經元如何
11:30
can do many, many, many things
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可以做很多、 很多、 很多的事情,
11:32
because of neuromodulation that can take place on a moment-by-moment basis.
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由於神經調節可以時時刻刻地進行。
11:36
So this is basically multiplexing in time.
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所以這基本上是時間復用。
11:39
Imagine a network of neurons with one neuromodulator.
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想像一個只有一個神經調節物質的神經網絡。
11:42
You select one set of cells to perform one sort of behavior,
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你選擇一組細胞執行一個行為、
11:45
another neuromodulator, another set of cells,
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另一個神經調節物質、另一組細胞、
11:48
a different pattern, and you can imagine
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另一種模式,你可以想像
11:49
you could extrapolate to a very, very complicated system.
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你可以推到一個非常、 非常複雜的系統。
11:53
Is there any evidence that flies do this?
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有任何證據說果蠅這麼做嗎?
11:55
Well, for many years in my laboratory and other laboratories around the world,
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嗯,多年來在我和其它世界各地實驗室,
11:59
we've been studying fly behaviors in little flight simulators.
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我們在研究微小飛行模擬器的飛行行為。
12:01
You can tether a fly to a little stick.
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你可以將果蠅綁到小棒子上。
12:03
You can measure the aerodynamic forces it's creating.
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你可以側量牠產生的空氣動力。
12:06
You can let the fly play a little video game
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你可以讓果蠅玩個小遊戲,
12:08
by letting it fly around in a visual display.
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讓牠在視覺影像間飛行。
12:12
So let me show you a little tiny sequence of this.
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讓我給你們看一個小小的影片。
12:14
Here's a fly
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這裡是一隻果蠅
12:16
and a large infrared view of the fly in the flight simulator,
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和一個大型飛行模擬的紅外視圖
12:19
and this is a game the flies love to play.
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和這個果蠅喜歡玩的遊戲。
12:21
You allow them to steer towards the little stripe,
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你允許牠們飛向小條紋,
12:23
and they'll just steer towards that stripe forever.
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牠們就會一直飛向那區。
12:26
It's part of their visual guidance system.
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這是牠們視覺引導的一部份。
12:30
But very, very recently, it's been possible
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但最近,已經可以藉由改變生理
12:32
to modify these sorts of behavioral arenas for physiologies.
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來改變行為的範疇。
12:37
So this is the preparation that one of my former post-docs,
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這是我之前一個博士後研究員的作法,
12:40
Gaby Maimon, who's now at Rockefeller, developed,
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蓋柏·買夢,他現在洛克菲勒,
12:42
and it's basically a flight simulator
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他建造這個基本上是一種飛行模擬器,
12:44
but under conditions where you actually can stick an electrode
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在實驗中你可以把電極置入
12:47
in the brain of the fly and record
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果蠅大腦中
12:49
from a genetically identified neuron in the fly's brain.
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並從一個已被辨別基因的神經元中紀錄。
12:53
And this is what one of these experiments looks like.
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這實驗看起來像這樣。
12:55
It was a sequence taken from another post-doc in the lab,
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這是另一個 博士後研究員貝蒂娜·靴諾
12:58
Bettina Schnell.
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的實驗影片。
12:59
The green trace at the bottom is the membrane potential
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在底部的綠色是果蠅腦內的
13:03
of a neuron in the fly's brain,
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一個神經元的膜電位。
13:05
and you'll see the fly start to fly, and the fly is actually
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你們將看到果蠅開始飛,
13:08
controlling the rotation of that visual pattern itself
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且果蠅是靠自身翅膀運動來控制
13:11
by its own wing motion,
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視覺模式中的旋轉。
13:12
and you can see this visual interneuron
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你們可以看到這個視覺中間神經元
13:14
respond to the pattern of wing motion as the fly flies.
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對果蠅翅膀運動作出回應。
13:18
So for the first time we've actually been able to record
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所以我們第一次實際記錄
13:21
from neurons in the fly's brain while the fly
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果蠅執行像是飛行這樣的複雜行為時
13:24
is performing sophisticated behaviors such as flight.
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腦內的神經元狀況。
13:28
And one of the lessons we've been learning
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我們一直在學習的是
13:30
is that the physiology of cells that we've been studying
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我們多年來在靜止果蠅身上
13:32
for many years in quiescent flies
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研究到的細胞生理
13:35
is not the same as the physiology of those cells
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與正在做一些像是
13:37
when the flies actually engage in active behaviors
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飛行或行走等主動行為時的
13:40
like flying and walking and so forth.
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果蠅細胞生理是不同的。
13:43
And why is the physiology different?
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為什麼細胞生理會不同呢?
13:46
Well it turns out it's these neuromodulators,
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事實是就是這些神經調節物質,
13:48
just like the neuromodulators in that little tiny ganglion in the crabs.
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就像是在螃蟹神經節上 的神經調節物質一樣。
13:52
So here's a picture of the octopamine system.
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這是章魚涎胺系統的圖片。
13:54
Octopamine is a neuromodulator
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章魚涎胺是一種神經調節物質,
13:56
that seems to play an important role in flight and other behaviors.
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它似乎在飛行和其他行為中具有重要的功用。
14:00
But this is just one of many neuromodulators
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但這只是果蠅大腦裡多種
14:03
that's in the fly's brain.
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神經調節物質的一種而已。
14:04
So I really think that, as we learn more,
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所以我真的認為,當我們瞭解更多後,
14:06
it's going to turn out that the whole fly brain
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我們會發現整個果蠅大腦
14:09
is just like a large version of this stomatogastric ganglion,
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就像這個放大版本的胃腸神經節,
14:12
and that's one of the reasons why it can do so much with so few neurons.
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這就是牠可以用 少量神經元執行大量功能的原因之一。
14:16
Now, another idea, another way of multiplexing
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現在,另一個想法,另一種多工的方式
14:19
is multiplexing in space,
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是在空間上的多工,
14:21
having different parts of a neuron
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讓神經元的不同部分
14:23
do different things at the same time.
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在同一時間做不同的事情。
14:25
So here's two sort of canonical neurons
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所以這裡是兩種典型的神經元排列,
14:27
from a vertebrate and an invertebrate,
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一個是脊椎動物、 另一個是無脊椎動物,
14:29
a human pyramidal neuron from Ramon y Cajal,
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從拉蒙·卡哈身上來的人類錐體神經元
14:32
and another cell to the right, a non-spiking interneuron,
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和在右側的細胞是 無動作電位中間神經元,
14:36
and this is the work of Alan Watson and Malcolm Burrows many years ago,
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這是很多年前, 艾倫 · 華生和瑪律科姆 · 巴路士的研究,
14:40
and Malcolm Burrows came up with a pretty interesting idea
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瑪律科姆 · 巴路士有一個很有趣的想法
14:43
based on the fact that this neuron from a locust
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是基於這個來自於蝗蟲的神經元
14:46
does not fire action potentials.
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不會觸發動作電位。
14:48
It's a non-spiking cell.
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它是一個無動作電位細胞。
14:50
So a typical cell, like the neurons in our brain,
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所以一個典型的細胞, 像我們的大腦中的神經元,
14:53
has a region called the dendrites that receives input,
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有個叫作樹突的部份會接收訊號,
14:55
and that input sums together
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這些訊號加總在一起
14:58
and will produce action potentials
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會產生動作電位,
15:00
that run down the axon and then activate
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這個電位會透過軸突傳遞然後
15:03
all the output regions of the neuron.
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啓動輸出區域的所有神經元。
15:05
But non-spiking neurons are actually quite complicated
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但無動作電位神經元其實是相當複雜,
15:08
because they can have input synapses and output synapses
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因為它們輸入突觸和輸出突觸合而為一,
15:11
all interdigitated, and there's no single action potential
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但卻沒有單一的動作電位
15:15
that drives all the outputs at the same time.
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可以在同一時間產生輸出。
15:18
So there's a possibility that you have computational compartments
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所以你有可能有不同的計算區域
15:22
that allow the different parts of the neuron
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使神經元的不同部分
15:26
to do different things at the same time.
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在同一時間做不同的事情。
15:28
So these basic concepts of multitasking in time
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這些基本的在時間上、
15:33
and multitasking in space,
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空間上的多工處理,
15:35
I think these are things that are true in our brains as well,
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我認為在我們的大腦中也成立,
15:38
but I think the insects are the true masters of this.
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但我認為昆蟲才是真正的行家。
15:41
So I hope you think of insects a little bit differently next time,
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所以,我希望你能對昆蟲另眼相看,
15:44
and as I say up here, please think before you swat.
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正如我所說: 在打牠前請記得想想牠的神奇之處。
15:47
(Applause)
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(掌聲)
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