I found myself in my bedroom

我發現我會在臥室裡

eating lots of Ben & Jerry's

大吃冰淇淋

watching some trashy TV

看些沒營養的電視節目

and maybe, maybe listening to Taylor Swift

而且也許，也許還會聽聽泰勒絲的歌

I had just gone through a breakup.

那時我剛失戀

(Laughter)

（笑聲）

So for the longest time, all I would do

大部分的時間裡我唯一做的事

is recall the memory of this person over and over again,

就是再三回憶與她的美好過往

wishing that I could get rid of that gut-wrenching,

希望可以擺脫那種撕心裂肺的痛楚

visceral "blah" feeling.

希望可以擺脫那種撕心裂肺的痛楚

Now, as it turns out, I'm a neuroscientist,

後來我成為一名神經學家

so I knew that the memory of that person

所以我清楚關於那人的回憶

and the awful, emotional undertones that color in that memory,

和其中隱含的糟糕又情緒化的部分

are largely mediated by separate brain systems.

受大腦中不同系統的影響很大

And so I thought, what if we could go into the brain

所以我想，要是我們能夠進入腦部

and edit out that nauseating feeling

刪除那些難受的情緒

but while keeping the memory of that person intact?

同時又保留關於那人的完整記憶，不是很好嗎？

Then I realized, maybe that's a little bit lofty for now.

後來我明瞭，也許這對現今而言是有點遙不可及

So what if we could start off by going into the brain

要是我們可以從進入大腦裡

and just finding a single memory to begin with?

先找到一段記憶作為開始呢？

Could we jump-start that memory back to life,

我們能再啟動那段記憶讓它起死回生、

maybe even play with the contents of that memory?

甚至玩弄那段記憶的內容嗎？

All that said, there is one person in the entire world right now

即便如此，我仍強烈希望她現在沒有看這個演講

that I really hope is not watching this talk.

即便如此，我仍強烈希望她現在沒有看這個演講

(Laughter)

（笑聲）

So there is a catch. There is a catch.

還有一個問題，棘手的問題

These ideas probably remind you of "Total Recall,"

這些想法可能會讓你聯想到《攔截記憶碼》

"Eternal Sunshine of the Spotless Mind,"

《王牌冤家》

or of "Inception."

或者《全面啟動》

But the movie stars that we work with

但是和我們共事的電影明星

are the celebrities of the lab.

可是實驗室的名人啊

Xu Liu: Test mice.

劉旭：實驗鼠

(Laughter)

（笑聲）

As neuroscientists, we work in the lab with mice

作為神經學家，我們在實驗室用老鼠做實驗

trying to understand how memory works.

為了了解記憶是如何運作的

And today, we hope to convince you that now

今天，我希望說服你們

we are actually able to activate a memory in the brain

我們現在能以光速啟動大腦裡的記憶

at the speed of light.

我們現在能以光速啟動大腦裡的記憶

To do this, there's only two simple steps to follow.

要做到這點，只需兩個簡單的步驟

First, you find and label a memory in the brain,

首先，在大腦裡找到一段記憶並將其標記

and then you activate it with a switch.

然後，用開關啟動它

As simple as that.

就這麼簡單

(Laughter)

（笑聲）

SR: Are you convinced?

斯蒂夫：你們被說服了嗎？

So, turns out finding a memory in the brain isn't all that easy.

其實，要在大腦裡找到一段記憶沒那麼容易

XL: Indeed. This is way more difficult than, let's say,

劉旭：的確，這可是比在乾草堆裡找針難多了

finding a needle in a haystack,

劉旭：的確，這可是比在乾草堆裡找針難多了

because at least, you know, the needle is still something

因為至少，你還能用手抓住那根針

you can physically put your fingers on.

因為至少，你還能用手抓住那根針

But memory is not.

但記憶卻不行

And also, there's way more cells in your brain

而且腦細胞的數量遠勝於

than the number of straws in a typical haystack.

乾草堆裡稻草的數量

So yeah, this task does seem to be daunting.

所以說，這個工作看來真令人卻步

But luckily, we got help from the brain itself.

但幸運的是，大腦給了我們幫助

It turned out that all we need to do is basically

事實證明，我們需要做的

to let the brain form a memory,

只是讓大腦形成一段記憶

and then the brain will tell us which cells are involved

然後大腦就會告訴我們哪些細胞

in that particular memory.

和那段記憶有關

SR: So what was going on in my brain

斯蒂夫：當回憶前任女友的時候

while I was recalling the memory of an ex?

我的大腦是什麼狀況呢？

If you were to just completely ignore human ethics for a second

假設你們現在暫且完全無視道德倫常

and slice up my brain right now,

把我的大腦切片

you would see that there was an amazing number

你們會發現當我回憶她的時候

of brain regions that were active while recalling that memory.

大腦的活躍區域數量之驚人

Now one brain region that would be robustly active

有一個極其活躍的大腦區域

in particular is called the hippocampus,

叫做海馬體

which for decades has been implicated in processing

數十年來它一直被視為

the kinds of memories that we hold near and dear,

處理跟我們所珍視的 與親愛的記憶相關的器官

which also makes it an ideal target to go into

它也成為我們試圖尋找、

and to try and find and maybe reactivate a memory.

甚至重新啟動某一段記憶的理想目標

XL: When you zoom in into the hippocampus,

劉旭：當把海馬體放大

of course you will see lots of cells,

你肯定會看到很多細胞

but we are able to find which cells are involved

但我們可以找到與某段記憶相關的細胞

in a particular memory,

但我們可以找到與某段記憶相關的細胞

because whenever a cell is active,

因為，當一個細胞呈現活躍的狀態

like when it's forming a memory,

例如一段記憶形成時

it will also leave a footprint that will later allow us to know

它也會留下一道印記，好讓我們知道

these cells are recently active.

這些細胞最近是活躍的

SR: So the same way that building lights at night

斯蒂夫：同樣地，晚上大樓有燈亮著時

let you know that somebody's probably working there at any given moment,

你會知道當時應該有人還在那兒工作

in a very real sense, there are biological sensors

確切地說，生物傳感器

within a cell that are turned on

當一個細胞在工作的時候

only when that cell was just working.

就會開啟

They're sort of biological windows that light up

它們有點像一個亮著的生物窗

to let us know that that cell was just active.

讓我們知道這個細胞是活躍的

XL: So we clipped part of this sensor,

劉旭：於是我們剪下部分的傳感器

and attached that to a switch to control the cells,

把它粘在細胞的開關上來控制細胞

and we packed this switch into an engineered virus

然後把這個開關塞進一個工程病毒裡

and injected that into the brain of the mice.

再注入老鼠的大腦

So whenever a memory is being formed,

所以，每當一段記憶形成時

any active cells for that memory

任何相關的活躍細胞

will also have this switch installed.

都會安裝上這個開關

SR: So here is what the hippocampus looks like

斯蒂夫：比如說，這就是海馬體

after forming a fear memory, for example.

形成一段恐懼記憶後的樣子

The sea of blue that you see here

你看到的藍色部份

are densely packed brain cells,

就是密集的腦細胞

but the green brain cells,

而這些綠色的腦細胞呢

the green brain cells are the ones that are holding on

綠色細胞就是與那段特定的恐懼記憶

to a specific fear memory.

緊密連結的細胞

So you are looking at the crystallization

你們看到的，就是那結晶體

of the fleeting formation of fear.

瞬間形成的恐懼結晶體

You're actually looking at the cross-section of a memory right now.

此刻你們看到的 其實是一段記憶的橫截面

XL: Now, for the switch we have been talking about,

劉旭：現在，談談我們剛才提到的開關

ideally, the switch has to act really fast.

理想狀態下，它必須運作得非常快

It shouldn't take minutes or hours to work.

幾分鐘或幾小時都太久了

It should act at the speed of the brain, in milliseconds.

它應以大腦的速度運作，以毫秒為單位

SR: So what do you think, Xu?

斯蒂夫：你怎麼看呢，阿旭？

Could we use, let's say, pharmacological drugs

我們能不能用像是... 藥

to activate or inactivate brain cells?

用藥來啟動或靜止腦細胞？

XL: Nah. Drugs are pretty messy. They spread everywhere.

劉旭：算了吧，用藥太麻煩了，搞得到處都是

And also it takes them forever to act on cells.

而且要對腦細胞起作用也太久了

So it will not allow us to control a memory in real time.

我們不可能透過藥來及時控制記憶

So Steve, how about let's zap the brain with electricity?

斯蒂夫，我們電擊大腦怎麼樣？

SR: So electricity is pretty fast,

斯蒂夫：電的速度也挺快的

but we probably wouldn't be able to target it

但是我們不太可能只擊中

to just the specific cells that hold onto a memory,

那些正好與某段記憶密切相關的細胞

and we'd probably fry the brain.

而且我們還可能把大腦給電糊了

XL: Oh. That's true. So it looks like, hmm,

劉旭：那倒是啊！嗯，那看來

indeed we need to find a better way

我們的確需要更好的方法

to impact the brain at the speed of light.

以光速來影響大腦

SR: So it just so happens that light travels at the speed of light.

斯蒂夫：恰巧，光是以光速行進的

So maybe we could activate or inactive memories

若我們要啟動或靜止記憶

by just using light --

光也許可以派上用場

XL: That's pretty fast.

劉旭：它的確很快

SR: -- and because normally brain cells

斯蒂夫：而且，正常情況下腦細胞

don't respond to pulses of light,

對光脈衝沒反應

so those that would respond to pulses of light

所以，那些對光脈衝有反應的細胞

are those that contain a light-sensitive switch.

就是安裝了光感開關的細胞

Now to do that, first we need to trick brain cells

要做到這個，我們先要哄騙腦細胞

to respond to laser beams.

讓它們對雷射光有反應

XL: Yep. You heard it right.

劉旭：對，你們沒聽錯

We are trying to shoot lasers into the brain.

我們要把雷射光射入大腦

(Laughter)

（笑聲）

SR: And the technique that lets us do that is optogenetics.

斯蒂夫：光基因技術使之成為可能

Optogenetics gave us this light switch that we can use

我們可以使用光基因技術的光開關

to turn brain cells on or off,

來啟動或靜止腦細胞

and the name of that switch is channelrhodopsin,

這個開關的名字就叫「通道視紫紅質」 （譯註︰又稱「光敏感通道」）

seen here as these green dots attached to this brain cell.

就是這些附在這個細胞上的綠點

You can think of channelrhodopsin as a sort of light-sensitive switch

你們可以把通道視紫紅質視為一種光感開關

that can be artificially installed in brain cells

它可以以人工的方式安裝在腦細胞上

so that now we can use that switch

所以我們可以透過

to activate or inactivate the brain cell simply by clicking it,

簡單地按下開關來啟動或靜止腦細胞

and in this case we click it on with pulses of light.

這裡呢，我們用光脈衝來開啟它

XL: So we attach this light-sensitive switch of channelrhodopsin

劉旭：於是我們把通道視紫紅質光感開關粘到

to the sensor we've been talking about

剛才提到的傳感器上

and inject this into the brain.

然後將其注入大腦

So whenever a memory is being formed,

所以，每當一段記憶形成時

any active cell for that particular memory

所有與那段記憶相關的活躍細胞

will also have this light-sensitive switch installed in it

都會被安裝上這個光感開關

so that we can control these cells

以便我們透過輕擊雷射開關

by the flipping of a laser just like this one you see.

來控制這些細胞，就像你們看到的這樣

SR: So let's put all of this to the test now.

斯蒂夫：現在讓我們對這些進行測試

What we can do is we can take our mice

我們能做的就是把老鼠

and then we can put them in a box that looks exactly like this box here,

放進這樣的一個盒子裡

and then we can give them a very mild foot shock

輕微地電擊牠們的足部

so that they form a fear memory of this box.

牠們對這個盒子便形成恐懼記憶

They learn that something bad happened here.

牠們記得在這裡發生過不好的事

Now with our system, the cells that are active

現在，透過我們的系統

in the hippocampus in the making of this memory,

這些在海馬體內活躍的細胞正形成記憶

only those cells will now contain channelrhodopsin.

只有那些細胞才含有通道視紫紅質

XL: When you are as small as a mouse,

劉旭：如果你像老鼠一樣小

it feels as if the whole world is trying to get you.

你會覺得全世界都想抓住你

So your best response of defense

所以你最好的防禦反應

is trying to be undetected.

就是盡量不被發現

Whenever a mouse is in fear,

當老鼠恐懼的時候

it will show this very typical behavior

就會表現出這種典型的行為

by staying at one corner of the box,

縮在盒子角落，一動也不動

trying to not move any part of its body,

縮在盒子角落，一動也不動

and this posture is called freezing.

這個姿勢叫做「行為凍結」

So if a mouse remembers that something bad happened in this box,

所以如果老鼠記得 在這個盒子裡發生過不好的事

and when we put them back into the same box,

當我們把牠們放回同一個盒子裡時

it will basically show freezing

就會表現出「行為凍結」

because it doesn't want to be detected

因為牠不想被盒子裡

by any potential threats in this box.

任何對牠構成威脅的物體發現

SR: So you can think of freezing as,

斯蒂夫：你們可以把「行為凍結」看作

you're walking down the street minding your own business,

當你自顧自的走在街上

and then out of nowhere you almost run into

突如其來你差點

an ex-girlfriend or ex-boyfriend,

撞見前女友或前男友

and now those terrifying two seconds

在那恐怖的兩秒間隔裡

where you start thinking, "What do I do? Do I say hi?

你會想︰「我該怎麼辦？要問好嗎？

Do I shake their hand? Do I turn around and run away?

要跟他們握手嗎？我該轉身跑掉嗎？

Do I sit here and pretend like I don't exist?"

我該待在原地假裝我不存在嗎？」

Those kinds of fleeting thoughts that physically incapacitate you,

那些閃念就會讓你的行為木訥

that temporarily give you that deer-in-headlights look.

會讓你當下看起來不知所措一臉茫然

XL: However, if you put the mouse in a completely different

然而，如果你把這隻老鼠放到

new box, like the next one,

一個全然不同的新盒子裡，比如這個

it will not be afraid of this box

牠就不會害怕這個盒子

because there's no reason that it will be afraid of this new environment.

因為牠沒理由害怕這個新環境

But what if we put the mouse in this new box

但是，若我們把這隻老鼠放到新盒子裡

but at the same time, we activate the fear memory

而且同時用雷射啟動牠的恐懼記憶呢？

using lasers just like we did before?

就像剛才那樣

Are we going to bring back the fear memory

我們能把第一個盒子裡的恐懼記憶

for the first box into this completely new environment?

帶到這個新環境嗎？

SR: All right, and here's the million-dollar experiment.

斯蒂夫：好，這就是那個寶貴的實驗

Now to bring back to life the memory of that day,

現在，把那天的記憶復甦吧

I remember that the Red Sox had just won,

我記得紅襪隊剛贏了比賽

it was a green spring day,

一個綠意盎然的春日

perfect for going up and down the river

正適合去溯溪

and then maybe going to the North End

也許再去北城

to get some cannolis, #justsaying.

買些奶酪卷，隨便說說而已

Now Xu and I, on the other hand,

而阿旭和我呢

were in a completely windowless black room

則在一個無窗的黑暗房間裡

not making any ocular movement that even remotely resembles an eye blink

目不轉睛連眨眼都沒有

because our eyes were fixed onto a computer screen.

因為我們的目光都聚焦在電腦螢幕上

We were looking at this mouse here trying to activate a memory

我們正盯著這隻老鼠

for the first time using our technique.

首次試著用我們的技術去啟動牠的記憶

XL: And this is what we saw.

劉旭：然後我們就看到了這個

When we first put the mouse into this box,

當我們第一次把老鼠放進盒子裡

it's exploring, sniffing around, walking around,

牠在熟悉環境、四處嗅嗅、到處走動

minding its own business,

專注著自己的事

because actually by nature,

因為天性使然

mice are pretty curious animals.

老鼠的好奇心很強

They want to know, what's going on in this new box?

牠們想知道這個新盒子裡是怎樣的

It's interesting.

很有趣

But the moment we turned on the laser, like you see now,

但是當我們開啟雷射時，就像你看到的

all of a sudden the mouse entered this freezing mode.

這隻老鼠突然就進入了「行為凍結」模式

It stayed here and tried not to move any part of its body.

牠待在原處試著不移動身體

Clearly it's freezing.

很明顯是「行為凍結」

So indeed, it looks like we are able to bring back

看起來，我們的確可以喚回

the fear memory for the first box

在第一個盒子裡的恐懼記憶

in this completely new environment.

並帶到這個全新的環境

While watching this, Steve and I

看到這個情況，斯蒂夫和我

are as shocked as the mouse itself.

像老鼠一樣震驚

(Laughter)

（笑聲）

So after the experiment, the two of us just left the room

實驗結束後，我們兩人離開了實驗室

without saying anything.

什麼也沒說

After a kind of long, awkward period of time,

一段又長又尷尬的時間之後

Steve broke the silence.

斯蒂夫打破了沉默

SR: "Did that just work?"

斯蒂夫：「剛才那個起作用了？」

XL: "Yes," I said. "Indeed it worked!"

劉旭：我說「對，起作用了！」

We're really excited about this.