Memory is such an everyday thing that we almost take it for granted.

記憶是日常生活中的一部分， 我們總是把它視為理所當然。

We all remember what we had for breakfast this morning

我們都記得早餐吃了什麼，

or what we did last weekend.

或者上週末做了什麼。

It's only when memory starts to fail

只有當記憶力開始衰退的時候，

that we appreciate just how amazing it is

我們才會感激它是如此神奇，

and how much we allow our past experiences to define us.

和反思我們如何讓 過去的經歷來定義自己。

But memory is not always a good thing.

但是，記憶不一定是好事。

As the American poet and clergyman John Lancaster Spalding once said,

就如美國詩人和牧師 約翰·蘭開斯特·史佩爾丁曾說過：

"As memory may be a paradise from which we cannot be driven,

「記憶可以是天堂， 在那裡我們不會被驅趕；

it may also be a hell from which we cannot escape."

記憶也可以是地獄， 在那裡我們無法逃脫。」

Many of us experience chapters of our lives

大多數人經歷過某些人生的章節，

that we would prefer to never have happened.

希望它從未發生過。

It is estimated that nearly 90 percent of us

估計我們當中大概大概有 90% 的人

will experience some sort of traumatic event during our lifetimes.

在一生中會經歷造成創傷的事件。

Many of us will suffer acutely following these events and then recover,

大多數人在這些事件之後 會非常痛苦，然後恢復，

maybe even become better people because of those experiences.

甚至因為這些經驗 而變成更好的人。

But some events are so extreme that many --

但是有些事件過於極端——

up to half of those who survive sexual violence, for example --

例如半數經歷過性暴力的人——

will go on to develop post-traumatic stress disorder,

會出現創傷後壓力症候群，

or PTSD.

又稱為 PTSD。

PTSD is a debilitating mental health condition

PTSD 是一個會導致 心理健康衰弱的疾病，

characterized by symptoms such as intense fear and anxiety

特徵是強烈恐懼和焦慮感、

and flashbacks of the traumatic event.

和經常回想起當時的情境等症狀。

These symptoms have a huge impact on a person's quality of life

這些症狀對人們的生活品質 有著重大的影響，

and are often triggered by particular situations

通常在特定的情況和環境下

or cues in that person's environment.

會引發這些症狀。

The responses to those cues may have been adaptive when they were first learned --

第一次發作後 人會習於自己所做的反應

fear and diving for cover in a war zone, for example --

——例如在戰場上撲向掩護地點——

but in PTSD,

但是 PTSD 的患者

they continue to control behavior when it's no longer appropriate.

仍受制於這些已不必要的行為。

If a combat veteran returns home and is diving for cover

有返家的退伍軍人因嚴重的焦慮，

when he or she hears a car backfiring

在聽到汽車的火爆聲時 仍會撲向掩護地點，

or can't leave their own home because of intense anxiety,

或無法離開家門。

then the responses to those cues, those memories,

那麼這些反應、記憶，

have become what we would refer to as maladaptive.

就成了我們所謂的適應不良。

In this way, we can think of PTSD as being a disorder of maladaptive memory.

PTSD 可被稱做 記憶適應不良的疾病。

Now, I should stop myself here,

現在，我必須暫停一下，

because I'm talking about memory as if it's a single thing.

因為我彷彿是在說記憶是單一的。

It isn't.

它不是。

There are many different types of memory,

人類有很多不同種類的記憶，

and these depend upon different circuits and regions within the brain.

它們取決於腦內不同的迴路和區域。

As you can see, there are two major distinctions in our types of memory.

如你所見，

There are those memories that we're consciously aware of,

我們的記憶類型有兩個主要區別。

where we know we know

首先是我們有意識的記憶。

and that we can pass on in words.

我們知道自己有這個記憶，

This would include memories for facts and events.

並且可以用文字表達。

Because we can declare these memories,

這包含資訊、事件等記憶。

we refer to these as declarative memories.

因為我們可以描述這些記憶，

The other type of memory is non-declarative.

我們稱它們為陳述性記憶。

These are memories where we often don't have conscious access

另一種記憶是非陳述性記憶。

to the content of those memories

對於這些記憶，

and that we can't pass on in words.

我們無法意識到記憶的內容，

The classic example of a non-declarative memory

並且無法用文字表達。

is the motor skill for riding a bike.

非陳述性記憶最經典的例子是

Now, this being Cambridge, the odds are that you can ride a bike.

騎自行車的運動技能。

You know what you're doing on two wheels.

在劍橋，你多半會騎自行車，

But if I asked you to write me a list of instructions

知道如何安坐在那兩輪之上。

that would teach me how to ride a bike,

但是如果我叫你列出指令

as my four-year-old son did when we bought him a bike

教我怎麼騎自行車——

for his last birthday,

就像我在兒子四歲生日時， 買給他腳踏車那樣——

you would really struggle to do that.

你會感到非常困難。

How should you sit on the bike so you're balanced?

要如何坐才能讓單車平衡？

How fast do you need to pedal so you're stable?

要踏多快才能平衡？

If a gust of wind comes at you,

如果一陣風吹過，

which muscles should you tense and by how much

你該用哪些肌肉出力多少

so that you don't get blown off?

才不會被風吹倒？

I'll be staggered if you can give the answers to those questions.

如果你能回答出這些問題， 我會感到非常的吃驚。

But if you can ride a bike, you do have the answers,

如果你會騎腳踏車， 你一定知道答案。

you're just not consciously aware of them.

你只是沒有意識到它們而已。

Getting back to PTSD,

回到 PTSD，

another type of non-declarative memory

另一種非陳述性記憶

is emotional memory.

是情緒的記憶。

Now, this has a specific meaning in psychology

在心理學，

and refers to our ability to learn about cues in our environment

它指的是我們對環境線索

and their emotional and motivational significance.

以及情感與動機的學習能力。

What do I mean by that?

那是什麼意思呢？

Well, think of a cue like the smell of baking bread,

想想看，線索就像是 烘烤麵包的香味，

or a more abstract cue like a 20-pound note.

或者更抽象的話， 一張 20 磅的紙幣。

Because these cues have been pegged with good things in the past,

因為這些線索會與美好的回憶相連，

we like them and we approach them.

因此我們喜歡並會接近它們。

Other cues, like the buzzing of a wasp, elicit very negative emotions

其他線索，例如黃蜂的嗡嗡聲，

and quite dramatic avoidance behavior in some people.

某些人會做出誇張的逃避行為。

Now, I hate wasps.

我討厭黃蜂。

I can tell you that fact.

我可以告訴你這個事實。

But what I can't give you are the non-declarative emotional memories

但是，我無法解釋 附近有黃蜂時我的反應。

for how I react when there's a wasp nearby.

一種非陳述性情緒記憶。

I can't give you the racing heart,

你無法感受到我的心跳加速、

the sweaty palms, that sense of rising panic.

流滿汗水的手掌和恐慌感。

I can describe them to you,

我能形容，

but I can't give them to you.

但你無法感受。

Now, importantly, from the perspective of PTSD,

重要的是自 PTSD 的角度

stress has very different effects on declarative and non-declarative memories

壓力對陳述性和非陳述性記憶

and the brain circuits and regions supporting them.

以及大腦回路和區域有不同的影響。

Emotional memory is supported by a small almond-shaped structure

支持情緒記憶的是

called the amygdala

被稱為「杏仁核」的 類似杏仁形狀的結構

and its connections.

及其連接。

Declarative memory, especially the what, where and when of event memory,

陳述性記憶，特別是 關於事件地點與時間的記憶，

is supported by a seahorse-shaped region of the brain

是由腦內一個海馬狀的區域紀錄的，

called the hippocampus.

稱為海馬迴。

The extreme levels of stress experienced during trauma

創傷造成的極端壓力

have very different effects on these two structures.

對這兩個結構的影響不同。

As you can see, as you increase a person's level of stress

如你所見，如果一個人的壓力上升，

from not stressful to slightly stressful,

從沒有壓力到稍微有點壓力，

the hippocampus,

海馬迴支撐事件的記憶，

acting to support the event memory,

會增加活動量，

increases in its activity

更好地維護陳述性記憶的儲存。

and works better to support the storage of that declarative memory.

但當壓力持續上升到中、高度壓力，

But as you increase to moderately stressful, intensely stressful

或是到了極高壓力時 ——像是遭受創傷後——

and then extremely stressful, as would be found in trauma,

海馬迴會自動關閉。

the hippocampus effectively shuts down.

也就是說，是創傷之後

This means that under the high levels of stress hormones

會導致壓力荷爾蒙飆高，

that are experienced during trauma,

不再保存詳盡的細節，

we are not storing the details,

那些關於事件、地點和時間的細節。

the specific details of what, where and when.

來看看正當壓力影響海馬迴的時候

Now, while stress is doing that to the hippocampus,

會怎麼影響杏仁核，

look at what it does to the amygdala,

發現在那個儲存著情感 和非陳述性記憶的重要部位

that structure important for the emotional, non-declarative memory.

活動會越來越強烈。

Its activity gets stronger and stronger.

所以 PTSD 會帶給我們過於強烈的情續

So what this leaves us with in PTSD

——例如恐懼記憶——

is an overly strong emotional -- in this case fear -- memory

這些記憶並不關聯到 特定的時間或地點，

that is not tied to a specific time or place,

這是因為海馬迴不保存 事件的地點和時間。

because the hippocampus is not storing what, where and when.

如此，這些提示 會在不適當的時刻控制人的行為，

In this way, these cues can control behavior

因而導致適應不良。

when it's no longer appropriate,

如果知道適應不良的記憶會導致 PTSD，

and that's how they become maladaptive.

我們是否可以運用這個知識

So if we know that PTSD is due to maladaptive memories,

來改善 PTSD 患者的治療結果呢？

can we use that knowledge to improve treatment outcomes

用於治療創傷後壓力候群症的 新方案以被開發，

for patients with PTSD?

它的目標是消除 適應不良的情緒記憶

A radical new approach being developed to treat post-traumatic stress disorder

導致的候群症。

aims to destroy those maladaptive emotional memories

這個方案最近幾年 才被視為一種可能性，

that underlie the disorder.

因為我們對記憶力的理解

This approach has only been considered a possibility

出現了極大的改變。

because of the profound changes in our understanding of memory

傳統上，人們認為創造記憶

in recent years.

就像是在筆記本裡用鋼筆寫字：

Traditionally, it was thought that making a memory

一旦墨水乾透之後， 你無法改變那些訊息。

was like writing in a notebook in pen:

人們曾經認為

once the ink had dried, you couldn't change the information.

為要提供更多的記憶容量，

It was thought that all those structural changes

腦內的結構能在六個小時內完成改變，

that happen in the brain to support the storage of memory

在那之後，記憶就會變成永久的。

were finished within about six hours,

這稱為記憶鞏固概念。

and after that, they were permanent.

然而最近的研究顯示，

This is known as the consolidation view.

創造記憶比較像 在文字處理程式裡寫字。

However, more recent research suggests that making a memory

最初我們創造記憶， 然後把它保存。

is actually more like writing in a word processor.

但是在某些情況下， 我們可以編輯那些記憶。

We initially make the memory and then we save it or store it.

記憶鞏固概念指出，

But under the right conditions, we can edit that memory.

大腦為了支撐記憶力 而作出的結構改變，

This reconsolidation view suggests that those structural changes

是可以撤消的，

that happen in the brain to support memory

即使是很舊的記憶。

can be undone,

這個記憶的編輯過程不常發生，

even for old memories.

只在特定的記憶檢索狀況下才會發生。

Now, this editing process isn't happening all the time.

讓我們將記憶檢索視為調用記憶，

It only happens under very specific conditions

就像是打開檔案一樣。

of memory retrieval.

通常我們只單純取出記憶，

So let's consider memory retrieval as being recalling the memory

就像是用「唯讀」模式來打開檔案。

or, like, opening the file.

但是，在正確的情況下，

Quite often, we are simply retrieving the memory.

我們可以打開檔案 並設置為編輯模式，

We're opening the file as read-only.

然後我們可以改變裡面的資料。

But under the right conditions,

理論上，我們可以刪除檔案內容，

we can open that file in edit mode,

當我們按下保存鍵的時候，

and then we can change the information.

那個檔案——也就是記憶——

In theory, we could delete the content of that file,

就會被存留下來。

and when we press save,

鞏固的概念

that is how the file -- the memory --

不只解釋記憶的奇怪之處

persists.

——像為什麼有時我們會記錯——

Not only does this reconsolidation view

它還可以讓我們消除

allow us to account for some of the quirks of memory,

PTSD 適應不良的恐懼記憶。

like how we all sometimes misremember the past,

我們只需兩樣：

it also gives us a way to destroy those maladaptive fear memories

讓記憶變得不穩定的方法 ——用編輯模式打開檔案——

that underlie PTSD.

和刪除資訊的方法。

All we would need would be two things:

對於如何刪除資訊的研究

a way of making the memory unstable -- opening that file in edit mode --

我們取得了極多的進展。

and a way to delete the information.

初期我們發現了一種

We've made the most progress

廣泛使用的血壓控制藥物

with working out how to delete the information.

——稱為普萘洛爾的 β 受體阻滯劑——

It was found fairly early on

可用於防止老鼠的恐懼記憶被鞏固。

that a drug widely prescribed to control blood pressure in humans --

在記憶編輯模式使用普萘洛爾後，

a beta-blocker called Propranolol --

老鼠似乎不再害怕 能觸發恐懼的線索。

could be used to prevent the reconsolidation

彷彿牠們未曾學過害怕那線索。

of fear memories in rats.

人類可以安全使用這個藥物。

If Propranolol was given while the memory was in edit mode,

不久之後，

rats behaved as if they were no longer afraid of a frightening trigger cue.

普萘洛爾也被發現可以 消除人類的恐懼記憶，

It was as if they had never learned to be afraid of that cue.

但重要的是，記憶要在 編輯模式才會成功。

And this was with a drug that was safe for use in humans.

那個研究採用了健康的志願者，

Now, not long after that,

這實驗非常重要，因為它證明了

it was shown that Propranolol could destroy fear memories in humans as well,

老鼠的研究結果跟人類相關，

but critically, it only works if the memory is in edit mode.

最終也證實可以醫治病人。

Now, that study was with healthy human volunteers,

對於人類，

but it's important because it shows that the rat findings

你可以測試看看 消除非陳述性情緒記憶

can be extended to humans and ultimately, to human patients.

會不會影響陳述性事件記憶。

And with humans,

這非常有趣。

you can test whether destroying the non-declarative emotional memory

即使讓記憶處於編輯模式的人 服用普萘洛爾後

does anything to the declarative event memory.

不再害怕激發恐懼的線索，

And this is really interesting.

他們依然能形容

Even though people who were given Propranolol

線索與恐怖結果之間的關聯。

while the memory was in edit mode

就像他們知道自己應該感到害怕，

were no longer afraid of that frightening trigger cue,

但卻不害怕。

they could still describe the relationship

這表明了普萘洛爾能針對 非陳述性情緒記憶，

between the cue and the frightening outcome.

同時完好無缺地保留著陳述性記憶。

It was as if they knew they should be afraid,

但要緊的是，普萘洛爾 只在編輯模式的情況下對記憶有作用。

and yet they weren't.

那麼怎樣把記憶變為不穩定呢？

This suggests that Propranolol can selectively target

如何進入編輯模式呢？

the non-declarative emotional memory

我的實驗室在這方面做了許多研究。

but leave the declarative event memory intact.

我們發現這需要依靠 一些不怎麼多的新資訊，

But critically, Propranolol can only have any effect on the memory

把它併入記憶中。

if it's in edit mode.

我們知道大腦會使用不同化學物質

So how do we make a memory unstable?

來提醒記憶需要被更新

How do we get it into edit mode?

並編輯檔案。

Well, my own lab has done quite a lot of work on this.

如今，我們大多數的研究 用在老鼠身上，

We know that it depends on introducing some but not too much new information

但是其他實驗室證實了 編輯人類記憶的方法也一樣，

to be incorporated into the memory.

即使病人有適應不良的記憶， 例如 PTSD。

We know about the different chemicals the brain uses

事實上，在不同國家裡，

to signal that a memory should be updated

數個治療 PTSD 的小型臨床試驗

and the file edited.

已經開始了，

Now, our work is mostly in rats,

並已取得理想的研究結果。

but other labs have found the same factors allow memories to be edited in humans,

這些需要更大規模地重複實驗，

even maladaptive memories like those underlying PTSD.

但所有的實驗結果

In fact, a number of labs in several different countries

都一致顯示可以治療 PTSD。

have begun small-scale clinical trials of these memory-destroying treatments

也許創傷性記憶未必是 我們無法逃脫的地獄。

for PTSD

雖然記憶刪除方案充滿希望，

and have found really promising results.

但是它並不直接了當，

Now, these studies need replication on a larger scale,

而且存有爭議。

but they show the promise of these memory-destroying treatments

消除記憶是人道的行為嗎？

for PTSD.

目擊者證詞又如何分辨是非呢？

Maybe trauma memories do not need to be the hell from which we cannot escape.

如果有人不能服用普萘洛爾呢？

Now, although this memory-destroying approach holds great promise,

因為會跟其他藥物相沖 而帶來負面影響。

that's not to say that it's straightforward

關於道德和目擊者證詞，

or without controversy.

注重的要點是：

Is it ethical to destroy memories?

研究人類所得的結果。

What about things like eyewitness testimony?

因為普萘洛爾只會影響 非陳述性情緒記憶，