the functions and structure of the human brain.

是的，就如克里斯的介紹，我研究人類的腦

And I just want you to think for a minute about what this entails.

人類大腦的功能和結構。

Here is this mass of jelly, three-pound mass of jelly

請大家試想一下，這牽涉到什麼？

you can hold in the palm of your hand,

人腦像一團三磅重的果凍，

and it can contemplate the vastness of interstellar space.

它可以放在手掌裡，

It can contemplate the meaning of infinity

它能思索浩瀚的星際空間，

and it can contemplate itself contemplating on the meaning of infinity.

能思索『無限』的含義，

And this peculiar recursive quality that we call self-awareness,

甚至能思索自身思索『無限』含義的這件事。

which I think is the holy grail of neuroscience, of neurology,

這種獨特的遞迴自省特質，稱為自我意識。

and hopefully, someday, we'll understand how that happens.

我認為這是神經科學和神經病學的終極目標和意義，

OK, so how do you study this mysterious organ?

希望有朝一日，我們能夠解開這個謎題。

I mean, you have 100 billion nerve cells,

那麼，我們要如何研究這個神秘的器官呢？

little wisps of protoplasm, interacting with each other,

人腦有1000億個神經元細胞，

and from this activity emerges the whole spectrum of abilities

每個都是一小束原生質，彼此交互作用，

that we call human nature and human consciousness.

從這些活動中，產生出多不勝數的能力

How does this happen?

即所謂人性和人的意識。

Well, there are many ways of approaching the functions of the human brain.

這是怎麼產生的呢？

One approach, the one we use mainly,

研究人腦功能的方法很多，

is to look at patients with sustained damage to a small region of the brain,

其中，最常採用的方法

where there's been a genetic change in a small region of the brain.

是觀察大腦中，一小部分區域遭受持續性損傷的病人，

What then happens is not an across-the-board reduction

研究已經發生某種基因改變的這一小部分腦區，

in all your mental capacities,

這並不是全面性喪失

a sort of blunting of your cognitive ability.

所有的心智能力，

What you get is a highly selective loss of one function,

而是認知能力變得遲鈍，

with other functions being preserved intact,

這是一種特定功能的喪失，

and this gives you some confidence in asserting

而其他功能則完好無損。

that that part of the brain is somehow involved in mediating that function.

我們幾乎可以確定，

So you can then map function onto structure,

大腦的這個區域影響該功能，

and then find out what the circuitry's doing

我們便可把功能對應到結構上，

to generate that particular function.

得知這部分神經迴路是如何產生

So that's what we're trying to do.

這個特定的功能，

So let me give you a few striking examples of this.

這就是我們的目標。

In fact, I'm giving you three examples, six minutes each, during this talk.

讓我向大家說明幾個驚人的例子，

The first example is an extraordinary syndrome called Capgras syndrome.

我要提出3個例子，每段說明6分鐘，

If you look at the first slide there,

首先，是一種非常奇特的『凱卜葛拉斯症候群』(Capgras Syndrome)。

that's the temporal lobes, frontal lobes, parietal lobes, OK --

在第一張幻燈片裡

the lobes that constitute the brain.

顯示的是顳葉(temporal lobes)、額葉(frontal lobes)和頂葉(parietal lobes)

And if you look, tucked away inside the inner surface of the temporal lobes --

這些是構成大腦的腦葉

you can't see it there --

仔細看，你會發現顳葉的皮層內部

is a little structure called the fusiform gyrus.

(這張圖裡看不出來)

And that's been called the face area in the brain,

是一種稱為梭狀回(fusiform gyrus)的微小結構

because when it's damaged, you can no longer recognize people's faces.

它被稱為腦的『臉部區域』

You can still recognize them from their voice

如果這個區域損傷，你就會喪失辨識別面孔的能力

and say, "Oh yeah, that's Joe,"

你還是可以從聲音辨識其人

but you can't look at their face and know who it is, right?

例如，你會說：『對，這個人是喬』

You can't even recognize yourself in the mirror.

但你卻無法看著別人的臉認出這是誰

I mean, you know it's you because you wink and it winks,

你甚至認不出鏡中的自己

and you know it's a mirror,

你對鏡中人眨眼，那人也會對你眨眼

but you don't really recognize yourself as yourself.

而且你知道那是一面鏡子

OK. Now that syndrome is well known as caused by damage to the fusiform gyrus.

可是卻認不出那個人就是你自己

But there's another rare syndrome, so rare, in fact,

我們已知這種症候群是由於梭狀回損傷所導致

that very few physicians have heard about it, not even neurologists.

但還有一種非常罕見的症候群

This is called the Capgras delusion,

連許多醫生、甚至神經科醫生都未曾聽聞，

and that is a patient, who's otherwise completely normal,

叫做『凱卜葛拉斯妄想症』(Capgras Delusion)

has had a head injury, comes out of coma,

一個原本腦部功能正常的人

otherwise completely normal, he looks at his mother

頭部受到損傷，從昏迷中醒來以後，

and says, "This looks exactly like my mother, this woman,

其他腦部功能都很正常，但是他看到自己的母親

but she's an impostor.

卻說：『這人看上去跟我母親一模一樣，

She's some other woman pretending to be my mother."

但她是個冒牌貨，

Now, why does this happen?

是個假扮我母親的女人。』

Why would somebody -- and this person is perfectly lucid and intelligent

為什麼會這樣呢？

in all other respects, but when he sees his mother,

為什麼這個人理智、且完全清醒

his delusion kicks in and says, it's not mother.

其他各腦部功能均完好，但是看到自己的母親，

Now, the most common interpretation of this,

卻產生錯覺，認為不是他的母親呢？

which you find in all the psychiatry textbooks,

目前最常見的解釋

is a Freudian view, and that is that this chap --

所有精神病學教科書的見解

and the same argument applies to women, by the way,

是佛洛伊德式的觀點：當這個男子

but I'll just talk about guys.

(其實女性也有同樣的情形)

When you're a little baby, a young baby,

(但我就以男性為例討論)

you had a strong sexual attraction to your mother.

(佛洛伊德認為) 男性在嬰兒時期

This is the so-called Oedipus complex of Freud.

對母親有強烈的性吸引力

I'm not saying I believe this,

即佛洛伊德所謂的『伊底帕斯』(Oedipus)戀母情結

but this is the standard Freudian view.

我並不支持這種論點

And then, as you grow up, the cortex develops,

但這是典型的佛洛伊德觀點。

and inhibits these latent sexual urges towards your mother.

隨著成長，腦皮層逐漸生長發育

Thank God, or you would all be sexually aroused when you saw your mother.

抑制了對母親的潛在性慾。

And then what happens is,

謝天謝地，否則你每次看到你母親就會性慾高漲。

there's a blow to your head, damaging the cortex,

但是，當頭部受傷，

allowing these latent sexual urges to emerge,

頭部的打擊損傷了腦皮層，

flaming to the surface, and suddenly and inexplicably

釋放了潛在的性衝動

you find yourself being sexually aroused by your mother.

浮現到最表層，突然間，莫名其妙地

And you say, "My God, if this is my mom,

你感覺到自己對母親產生了性慾

how come I'm being sexually turned on?

於是你想：『天啊，如果這是我媽，

She's some other woman. She's an impostor."

我怎麼可能會有性衝動？

It's the only interpretation that makes sense to your damaged brain.

她一定是別的女人，是個冒牌貨。』

This has never made much sense to me, this argument.

你受傷的大腦認為，只有這樣解釋才合理。

It's very ingenious, as all Freudian arguments are --

但我從不認同這種看法。

(Laughter)

這個主張就像佛洛伊德所有的理論一樣，非常精闢

-- but didn't make much sense because I have seen the same delusion,

(笑聲)

a patient having the same delusion, about his pet poodle.

但是卻不合理，因為我曾經目睹同樣的錯覺

(Laughter)

發生在一名病患對他的貴賓狗身上。

He'll say, "Doctor, this is not Fifi. It looks exactly like Fifi,

(笑聲)

but it's some other dog." Right?

他說：『醫生，這不是菲菲吧，牠長的跟菲菲一模一樣，

Now, you try using the Freudian explanation there.

但牠是另一條狗。』對吧？

(Laughter)

現在請你套用佛洛伊德的理論解釋看看，

You'll start talking about the latent bestiality in all humans,

(笑聲)

or some such thing, which is quite absurd, of course.

會認為人類有潛在的戀獸性，

Now, what's really going on?

或是其他類似的論點，這都是非常荒謬的。

So, to explain this curious disorder,

所以，實際情形究竟是怎麼回事呢？

we look at the structure and functions of the normal visual pathways in the brain.

要解釋這種奇怪的症狀，

Normally, visual signals come in, into the eyeballs,

我們來看看正常人腦視覺通路的結構和功能。

go to the visual areas in the brain.

正常情況下，視覺訊號通過眼球，

There are, in fact, 30 areas in the back of your brain concerned with just vision,

進入腦中的視覺區域。

and after processing all that, the message goes to a small structure

事實上，腦後部有30個專門負責視覺的區域。

called the fusiform gyrus, where you perceive faces.

經過這些區域處理之後，訊號會進入一個微小結構，

There are neurons there that are sensitive to faces.

稱為『梭狀回』，就是感知面孔的地方，

You can call it the face area of the brain, right?

那裡有對面孔敏感的神經元。

I talked about that earlier.

我們可以稱它為『大腦的面部區』，

Now, when that area's damaged, you lose the ability to see faces, right?

我稍早提過。

But from that area, the message cascades

這個區域一旦損壞，你就失去了識別面孔的能力。對吧？

into a structure called the amygdala in the limbic system,

但神經訊號還會通過那個區域，

the emotional core of the brain,

進入大腦邊緣系統(limbic system)的杏仁核(amygdala)，

and that structure, called the amygdala,

這是腦的情緒核心，

gauges the emotional significance of what you're looking at.

而這個稱為杏仁核的結構，

Is it prey? Is it predator? Is it mate?

會判斷你所看見的物體在情緒上的重要性。

Or is it something absolutely trivial, like a piece of lint,

在你眼前的，是獵物？掠食者？還是配偶？

or a piece of chalk, or a -- I don't want to point to that, but --

還是完全無關緊要的東西，如衣服上的毛球，

or a shoe, or something like that? OK?

或者一支粉筆。或是，我不想指出來了..

Which you can completely ignore.

或者是一只鞋子等等，

So if the amygdala is excited, and this is something important,

可以毫不理會的東西。

the messages then cascade into the autonomic nervous system.

如果杏仁核變得興奮，表示這個東西對你很重要，

Your heart starts beating faster.

神經訊號就會繼續傳到自主神經系統，

You start sweating to dissipate the heat that you're going to

你的心跳會開始加速，

create from muscular exertion.

你會開始出汗，排除因緊張而產生的體熱

And that's fortunate, because we can put two electrodes on your palm

即肌肉緊繃引起的。

and measure the change in skin resistance produced by sweating.

這樣便於偵測，因為我們可以在你的手掌心貼上兩個電極

So I can determine, when you're looking at something,

來測量汗液導致的皮膚電阻變化。

whether you're excited or whether you're aroused, or not, OK?

如此就能判斷，當你看著某樣東西，

And I'll get to that in a minute.

是否感覺興奮？或是有沒有被挑起慾望。對吧？

So my idea was, when this chap looks at an object, when he looks at his --

這點待會我會進一步說明。

any object for that matter, it goes to the visual areas and,

所以我認為，當這個人看著某物時，

however, and it's processed in the fusiform gyrus,

或者任何物體，訊號傳到視覺區

and you recognize it as a pea plant, or a table,

傳入梭狀回處理

or your mother, for that matter, OK?

便可認出這是一顆豌豆、一張桌子，

And then the message cascades into the amygdala,

或是他的母親，對吧？

and then goes down the autonomic nervous system.

接著，訊號繼續傳到杏仁核，

But maybe, in this chap, that wire that goes from the amygdala to the limbic system,

再傳到自主神經系統。

the emotional core of the brain, is cut by the accident.

但是，或許這個病患腦中，從杏仁核到邊緣系統的線路

So because the fusiform is intact,

即連接大腦控制情緒核心的線路，在事故中被切斷了。

the chap can still recognize his mother,

他的梭狀回完好無損，

and says, "Oh yeah, this looks like my mother."

所以還能認出他的母親，

But because the wire is cut to the emotional centers,

心想：『是啊，這女人長得跟我母親一樣。』

he says, "But how come, if it's my mother, I don't experience a warmth?"

但由於通往情緒中心的線路被截斷了，

Or terror, as the case may be? Right?

他就會懷疑：『如果真是我母親， 為什麼我看見她卻沒有溫暖的感覺？』

(Laughter)

或者有些人可能會產生恐懼感，嗯？

And therefore, he says, "How do I account for this inexplicable lack of emotions?

(笑聲)

This can't be my mother.

於是他會想：『該如何解釋我的欠缺情緒反應呢？

It's some strange woman pretending to be my mother."

她不可能是我的母親。

How do you test this?

是某個陌生女人假裝是我的母親。』

Well, what you do is, if you take any one of you here, and put you in front of a screen,

這種現象該如何驗證呢？

and measure your galvanic skin response,

方法是，例如，請你們其中一位觀眾上來站在螢幕前，

and show pictures on the screen,

我一邊測量你的皮膚電反應(GSR)，

I can measure how you sweat when you see an object,

一邊在螢幕上播放圖片給你看。

like a table or an umbrella. Of course, you don't sweat.

我可以測量你看見各個物體時的出汗情形。

If I show you a picture of a lion, or a tiger, or a pinup, you start sweating, right?

例如，看見桌子或雨傘時，你當然不至於出汗，

And, believe it or not, if I show you a picture of your mother --

如果看到獅子、老虎或性感女郎，你就會冒汗了。對吧？

I'm talking about normal people -- you start sweating.

信不信，如果我給你看你母親的照片，

You don't even have to be Jewish.

我是指一般正常人，就會開始流汗，

(Laughter)

不一定是猶太人才有這種反應。 (譯註：猶太媽媽的刻版印象是專橫嘮叨、管教甚嚴)

Now, what happens if you show this patient?

(笑聲)

You take the patient and show him pictures on the screen

同樣的實驗，對前述的病患，反應又是如何呢？

and measure his galvanic skin response.

你把他帶到螢幕前，播放圖片給他看，

Tables and chairs and lint, nothing happens, as in normal people,

測量他的皮膚電反應(GSR)。

but when you show him a picture of his mother,

看桌子、椅子、毛球，沒有反應，跟正常人一樣；

the galvanic skin response is flat.

但是當你給他看他母親的照片，

There's no emotional reaction to his mother,

皮膚電圖像還是平的，

because that wire going from the visual areas to the emotional centers is cut.

他對自己的母親也沒有情緒反應，

So his vision is normal because the visual areas are normal,

因為從視覺區通往情緒中心的線路被切斷了。

his emotions are normal -- he'll laugh, he'll cry, so on and so forth --

他的視覺沒有問題，因為視覺區功能正常，

but the wire from vision to emotions is cut

他的情緒反應能力也沒有問題，他會哭會笑，等等

and therefore he has this delusion that his mother is an impostor.

但是從視覺到情緒的線路卻阻斷了，

It's a lovely example of the sort of thing we do:

因此他會產生錯覺，認為他母親是冒牌貨。

take a bizarre, seemingly incomprehensible, neural psychiatric syndrome

這個有趣的例子可以說明我們從事的研究，

and say that the standard Freudian view is wrong,

探究這類奇特、看似無法理解的神經精神症候群，

that, in fact, you can come up with a precise explanation

來證明傳統佛洛伊德觀點的謬誤，

in terms of the known neural anatomy of the brain.

事實上，你可以找到精確的解釋，

By the way, if this patient then goes,

從已知的大腦神經解剖學找出答案。

and mother phones from an adjacent room -- phones him --

順帶一提，如果這個病人離開，

and he picks up the phone, and he says, "Wow, mom, how are you? Where are you?"

他母親從隔壁打電話來，

There's no delusion through the phone.

他會接起電話說：『哇，媽，妳好不好？妳在哪裡？』

Then, she approaches him after an hour, he says, "Who are you?

透過電話，不會產生錯覺。

You look just like my mother." OK?

一小時後，當母親走到他面前，他又會問：『妳是誰呀？

The reason is there's a separate pathway

妳長得跟我母親一模一樣！』

going from the hearing centers in the brain to the emotional centers,

原因是，有另一條通路

and that's not been cut by the accident.

從腦的聽覺中心通往情緒中心，

So this explains why through the phone he recognizes his mother, no problem.

這條通路並沒有被事故切斷。

When he sees her in person, he says it's an impostor.

這是為什麼他能透過電話認出母親，毫無問題；

OK, how is all this complex circuitry set up in the brain?

但是當他看到母親本人，卻說她是假冒者。

Is it nature, genes, or is it nurture?

大腦究竟是如何建構發展出如此複雜的迴路呢？

And we approach this problem

是先天、基因、還是後天的作用？

by considering another curious syndrome called phantom limb.

要解開這個謎題，

And you all know what a phantom limb is.

可透過研究另一種奇特的症候群，稱為『幻肢』。

When an arm is amputated, or a leg is amputated, for gangrene,

各位都知道幻肢是什麼

or you lose it in war -- for example, in the Iraq war,

當一條手臂或腿因為壞疽被切除，

it's now a serious problem --

或在戰爭(如伊拉克戰爭)中失去，

you continue to vividly feel the presence of that missing arm,

我們發現這會產生嚴重的問題

and that's called a phantom arm or a phantom leg.

傷者仍能強烈地感受到那條已經失去的手臂的存在，

In fact, you can get a phantom with almost any part of the body.

這就是所謂的幻臂(phantom arm)或幻腿(phantom leg)。

Believe it or not, even with internal viscera.

事實上，身體任何部位都有可能產生這種幻肢現象，

I've had patients with the uterus removed -- hysterectomy --

甚至連內臟器官都有可能。

who have a phantom uterus, including phantom menstrual cramps

我有位病人，做子宮切除術除去了子宮，

at the appropriate time of the month.

她得了幻子宮症，還會有幻經痛

And in fact, one student asked me the other day,

每個月都會定期感到經痛。

"Do they get phantom PMS?"

甚至，前幾天還有學生問我，

(Laughter)

她們有沒有幻經前症候群？

A subject ripe for scientific enquiry, but we haven't pursued that.

(笑聲)

OK, now the next question is,

這頗值得科學研究，但我們還沒有探討過。

what can you learn about phantom limbs by doing experiments?

好了，接下來的問題是：

One of the things we've found was,

我們能透過實驗，對幻肢現象獲得什麼了解？

about half the patients with phantom limbs

我們發現，

claim that they can move the phantom.

半數的幻肢病患，

It'll pat his brother on the shoulder,

宣稱自己可以移動那條幻肢。

it'll answer the phone when it rings, it'll wave goodbye.

能用幻肢拍兄弟的肩膀，

These are very compelling, vivid sensations.

能在電話鈴響時拿起聽筒，還能揮手道別。

The patient's not delusional.

這些感覺真實而強烈，

He knows that the arm is not there,

病患並不是在妄想。

but, nevertheless, it's a compelling sensory experience for the patient.