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  • Fifteen years ago, it was widely assumed

    在15年前, 大家普遍地認為

  • that the vast majority of brain development

    腦部的發育成長, 主要都在

  • takes place in the first few years of life.

    剛出生的前幾個年頭發生

  • Back then, 15 years ago, we didn't have the ability

    在15年前做研究的人

  • to look inside the living human brain

    並無法觀察到活生生的人的腦部運作

  • and track development across the lifespan.

    更談不上追蹤人的一生期間的腦部發展

  • In the past decade or so, mainly due to advances

    但在過去的十年間

  • in brain imaging technology

    主要由於腦部造影技術的發展

  • such as magnetic resonance imaging, or MRI,

    例如: 核磁共振造影, 簡稱 MRI

  • neuroscientists have started to look inside the living

    神經學研究者開始有辦法看到, 各年齡層的

  • human brain of all ages, and to track changes

    活生生的人的腦部運作, 並且追蹤隨著時間

  • in brain structure and brain function,

    腦部結構與功能所發生的改變

  • so we use structural MRI if you'd like to take a snapshot,

    因此,若要觀察腦部結構, 我們會使用結構性的MRI

  • a photograph, at really high resolution of the inside

    一張高解析度的照片, 可以看到活著的人的

  • of the living human brain, and we can ask questions like,

    腦內結構, 可以解答我們的這些疑問, 例如:

  • how much gray matter does the brain contain,

    大腦裡的灰質占了多少?

  • and how does that change with age?

    隨著年齡又有什麼樣的變化

  • And we also use functional MRI, called fMRI,

    我們也可以使用功能性的MRI, 又稱 fMRI

  • to take a video, a movie, of brain activity

    來拍攝大腦活動的影片

  • when participants are taking part in some kind of task

    被拍攝的人同時正在進行某項工作

  • like thinking or feeling or perceiving something.

    比如思考或感覺或感知某些事物

  • So many labs around the world are involved in this kind

    世界各地有很多實驗室都在參與這種

  • of research, and we now have a really rich

    研究,我們現在擁有大量的觀察資料

  • and detailed picture of how the living human brain develops,

    記錄活的人的腦部發展的的詳細照片/影片

  • and this picture has radically changed the way

    這些影像資料完全改變了

  • we think about human brain development

    我們對人類大腦發展的觀點

  • by revealing that it's not all over in early childhood,

    資料顯示了, 人腦並非僅在童年早期就發展完畢

  • and instead, the brain continues to develop

    相反的, 大腦持續在發展, 延續到

  • right throughout adolescence and into the '20s and '30s.

    整個青春期, 一直到 廿幾 到 卅幾 歲 都還在發展

  • So adolescence is defined as the period of life that starts

    青春期的定義, 是一段生命的期間, 始於

  • with the biological, hormonal, physical changes of puberty

    生物上的、 內分泌上的、 身體上的改變

  • and ends at the age at which an individual attains

    一直到個人建立了一個社會中的

  • a stable, independent role in society.

    穩定而且獨立的地位的時間為止

  • (Laughter)

    (笑聲)

  • It can go on a long time. (Laughter)

    青春期有可能延續的很長久(笑聲)

  • One of the brain regions that changes most dramatically

    在青春期, 腦部劇烈改變的區域之一,

  • during adolescence is called prefrontal cortex.

    叫做 前額葉皮層。

  • So this is a model of the human brain,

    這裡是一個人的腦部的模型

  • and this is prefrontal cortex, right at the front.

    而這是前額葉皮層,就在前面。

  • Prefrontal cortex is an interesting brain area.

    前額葉皮層是一個有趣的大腦區域。

  • It's proportionally much bigger in humans than

    比例上來說, 人腦的前額葉皮層遠大於

  • in any other species, and it's involved in a whole range of

    任何其他物種,這個腦部區域負責一系列的

  • high level cognitive functions, things like decision-making,

    抽象認知功能,如決策,

  • planning, planning what you're going to do tomorrow

    規劃,規劃你明天要做的事情

  • or next week or next year, inhibiting

    或是下星期或明年,這個腦區也會抑制

  • inappropriate behavior, so stopping yourself saying

    不適當的行為,比方阻止你自己說出

  • something really rude or doing something really stupid.

    一些粗魯的話語, 或是做很蠢的事情

  • It's also involved in social interaction,

    這個腦區也涉及社會互動,

  • understanding other people, and self-awareness.

    瞭解其他人, 還有自我知覺

  • So MRI studies looking at the development of this region

    有些 MRI 研究觀察了這個腦區的發展

  • have shown that it really undergoes dramatic development

    發現在這個區域經歷了劇烈的變化

  • during the period of adolescence.

    在青春期的期間

  • So if you look at gray matter volume, for example,

    例如, 就 灰質的體積來說

  • gray matter volume across age from age four to 22 years

    從4歲到22歲的期間, 灰質的體積

  • increases during childhood, which is what you can see

    在兒童時期開始增加, 如同你在投影片上看到的

  • on this graph. It peaks in early adolescence.

    增加到頂的時候, 大約是青春期的早期

  • The arrows indicate peak gray matter volume

    兩個箭頭標示著 前額葉皮層 灰質最高的時間點

  • in prefrontal cortex. You can see that that peak happens

    你可以看到這個最高點在女生較早發生

  • a couple of years later in boys relative to girls,

    而男生的最高點則晚了一兩年

  • and that's probably because boys go through puberty

    這有可能是因為男孩進入青春期的年紀

  • a couple of years later than girls on average,

    普遍來說比女孩晚上一兩年

  • and then during adolescence, there's a significant decline

    然後在後續的青春期, 數值就明顯地下降

  • in gray matter volume in prefrontal cortex.

    前額葉皮層的灰質體積一路降低

  • Now that might sound bad, but actually this is

    這聽起來好像不太好, 但事實上

  • a really important developmental process, because

    這是真正重要的發展過程,因為

  • gray matter contains cell bodies and connections

    灰質包含細胞本體, 還有細胞間的連接器

  • between cells, the synapses, and this decline

    又稱為 神經突觸,

  • in gray matter volume during prefrontal cortex

    這段期間發生的額葉皮層的灰質減少

  • is thought to correspond to synaptic pruning,

    被解讀成 突觸 修剪的過程

  • the elimination of unwanted synapses.

    把不需要的神經突觸刪去

  • This is a really important process. It's partly dependent

    這是一個非常重要的過程。有一部分是因為

  • on the environment that the animal or the human is in,

    這個動物或人類所處的環境的影響

  • and the synapses that are being used are strengthened,

    讓有用到的突觸變強

  • and synapses that aren't being used

    而在所處環境下用不到的突觸

  • in that particular environment are pruned away.

    就被修剪掉了。

  • You can think of it a bit like pruning a rosebush.

    你可以把它想像如同修剪薔薇叢。

  • You prune away the weaker branches so that

    你會把較弱的分支剪掉

  • the remaining, important branches, can grow stronger,

    讓留下來的, 較重要的分支, 可以長得更好

  • and this process, which effectively fine-tunes brain tissue

    這樣的過程, 有效地微調了腦部的組織

  • according to the species-specific environment,

    來因應該物種所處的特定的環境

  • is happening in prefrontal cortex and in other brain regions

    這個過程 發生在前額葉皮層, 還有大腦的其他區域

  • during the period of human adolescence.

    在人類青春期的期間。

  • So a second line of inquiry that we use to track changes

    第二層的研究, 是用功能性的 MRI (fMRI)

  • in the adolescent brain is using functional MRI

    來追蹤青春期的腦部的變化

  • to look at changes in brain activity across age.

    各個年齡階段腦部活動狀況有什麼改變

  • So I'll just give you an example from my lab.

    這裡用我的實驗室的一個例子來說明

  • So in my lab, we're interested in the social brain, that is

    我的實驗室研究的是 "社交腦",就是

  • the network of brain regions that we use to understand

    大腦各區域的相互連結, 讓人類可以理解

  • other people and to interact with other people.

    其他人,並與其他人進行互動。

  • So I like to show a photograph of a soccer game

    這裡我想展示一張在足球賽裡拍的照片

  • to illustrate two aspects of how your social brains work.

    來說明你的 社交腦 運作的兩個面向

  • So this is a soccer game. (Laughter)

    在這場足球賽裡(笑聲)

  • Michael Owen has just missed a goal, and he's lying

    麥克 · 歐文 剛剛射門沒進,他正躺在地上

  • on the ground, and the first aspect of the social brain

    你的社交腦的第一個面向

  • that this picture really nicely illustrates is how automatic

    可以用這張照片貼切的展現出來, 就是 社交情緒

  • and instinctive social emotional responses are,

    是如此自動且本能的流露出來

  • so within a split second of Michael Owen missing this goal,

    所以只在 麥克 · 歐文 射門沒進的 幾分之一秒裡

  • everyone is doing the same thing with their arms

    每個人的反應都一樣, 雙手抱頭

  • and the same thing with their face, even Michael Owen

    臉上的表情也都一樣, 就連 麥克 · 歐文

  • as he slides along the grass, is doing the same thing

    在滑倒在草皮上的時候, 也是相同的動作與表情

  • with his arms, and presumably has a similar

    雙手也抱著頭, 臉上應該也是一樣的表情

  • facial expression, and the only people who don't

    而照片中有議群與眾不同的

  • are the guys in yellow at the back — (Laughs) —

    是在後面的黃色的傢伙 — — (笑) — —

  • and I think they're on the wrong end of the stadium,

    我想他們應該是坐錯邊了, 跑到敵隊陣營裡了

  • and they're doing another social emotional response

    他們有著另一種社交情緒反應

  • that we all instantly recognize, and that's the second aspect

    我們大家都馬上就認出來了, 這也是社交腦的第二個面向

  • of the social brain that this picture really nicely illustrates,

    透過這張找片很好地展現了

  • how good we are at reading other people's behavior,

    我們是多麼地善於解讀別人的舉動

  • their actions, their gestures, their facial expressions,

    從 他們的行動,他們的手勢,臉部表情,

  • in terms of their underlying emotions and mental states.

    可以知道他們蘊含的情感與心裡面的狀態

  • So you don't have to ask any of these guys.

    所以你不必開口問這些人

  • You have a pretty good idea of what they're feeling

    就能相當了解他們的感受

  • and thinking at this precise moment in time.

    還有在那個時刻的他們的想法

  • So that's what we're interested in looking at in my lab.

    這就是我的實驗室有興趣研究的

  • So in my lab, we bring adolescents and adults into the lab

    所以在我的實驗室, 我們邀來了青少年和成人

  • to have a brain scan, we give them some kind of task

    來進行腦部掃描,我們會給他們一些任務

  • that involves thinking about other people, their minds,

    任務中涉及了, 猜測其他人心裡想什麼

  • their mental states, their emotions, and one of the findings

    其他人的精神狀態、 情緒。我們有一項發現

  • that we've found several times now, as have other labs

    我們重覆觀察到好幾次, 也有其他的實驗室

  • around the world, is part of the prefrontal cortex called

    在世界其他地方觀察到,大腦前額葉皮層的一部分

  • medial prefrontal cortex, which is shown in blue on the slide,

    叫做 內側前額葉皮層,在投影片上標示藍色的地方

  • and it's right in the middle of prefrontal cortex

    就在 前額葉皮層的中間

  • in the midline of your head.

    在你的頭中線。

  • This region is more active in adolescents when they make

    青少年的這個區域變得更加活躍, 當他們進行

  • these social decisions and think about other people

    一些社交決定, 還有想到其他人的時候

  • than it is in adults, and this is actually a meta-analysis

    成人相對就沒那麼活躍。這項分析集合了

  • of nine different studies in this area from labs around

    這個領域在全球各地的實驗室的九項不同研究結果

  • the world, and they all show the same thing, that activity

    所有研究都顯示了相同的狀況, 就是

  • in this medial prefrontal cortex area decreases

    內側前額葉皮層區的活動降低的現象

  • during the period of adolescence.

    出現在青春期的被觀察者腦部

  • And we think that might be because adolescents and adults

    我們認為這可能是由於青少年和成人

  • use a different mental approach, a different

    使用不同的思維方式,不同

  • cognitive strategy, to make social decisions,

    認知策略,來進行社交的決定

  • and one way of looking at that is to do behavioral studies

    要研究這件事的方法之一, 是透過行為研究

  • whereby we bring people into the lab and we give them

    我們把人請到實驗室裡, 並請他們

  • some kind of behavioral task, and I'll just give you

    進行某些行為上的工作項目。這裡我會說明

  • another example of the kind of task that we use in my lab.

    另一個例子, 關於在實驗室中採用的工作項目

  • So imagine that you're the participant in one of our

    想像一下, 你是我們請來參與實驗的其中一人

  • experiments. You come into the lab,

    你走進實驗室,

  • you see this computerized task.

    你看到這個電腦化的任務。

  • In this task, you see a set of shelves.

    在此任務中,你看到一組貨架。

  • Now, there are objects on these shelves, on some of them,

    這些貨架上有些格子裡擺了東西

  • and you'll notice there's a guy standing behind the set

    你會注意到有一個人站在貨架的另一邊

  • of shelves, and there are some objects that he can't see.

    而且有一些格子的東西他是看不到的

  • They're occluded, from his point of view, with a kind of

    這些格子從他那邊看, 是被擋住的, 他只看得到

  • gray piece of wood.

    灰色的木板

  • This is the same set of shelves from his point of view.

    這是他的方向看過來的同一個貨架

  • Notice that there are only some objects that he can see,

    請注意, 他只能所看到的一部分的物件

  • whereas there are many more objects that you can see.

    而從你這邊, 你可以看到更多的物件

  • Now your task is to move objects around.

    現在你的任務是要移動物件。

  • The director, standing behind the set of shelves,

    站在貨架對面的人是指揮者

  • is going to direct you to move objects around,

    將會給你搬動物件的指令

  • but remember, he's not going to ask you to move objects

    但是請記住,他不會叫你去搬動那些

  • that he can't see. This introduces a really interesting

    他看不到的物件。這就帶來了非常有趣狀況:

  • condition whereby there's a kind of conflict

    其中存在著一種衝突性

  • between your perspective and the director's perspective.

    就是你的視角與指揮者的視角的不同

  • So imagine he tells you to move the top truck left.

    所以想像若他告訴, 把最上層的卡車向左移

  • There are three trucks there. You're going to instinctively

    你看得到三輛卡車, 本能地你會想去搬

  • go for the white truck, because that's the top truck

    白色的卡車,因為這是最上層的卡車

  • from your perspective, but then you have to remember,

    從您的角度看,但是你要記得

  • "Oh, he can't see that truck, so he must mean

    "哦,他看不到那輛卡車,所以他說的應該是

  • me to move the blue truck," which is the top truck

    要我搬藍色的卡車" 這才是最上層的卡車

  • from his perspective. Now believe it or not,

    從他的角度看。那麼, 不知道你信不信

  • normal, healthy, intelligent adults like you make errors

    像你這樣的正常、 健康、 聰明的成人, 出錯的

  • about 50 percent of the time on that kind of trial.

    比例大概是 50%, 在這樣的實驗裡.

  • They move the white truck instead of the blue truck.

    他們去搬白色卡車, 而不是藍色的。

  • So we give this kind of task to adolescents and adults,

    我們把這樣的工作交給參加實驗的青少年與成人

  • and we also have a control condition

    我們也設計了一個控制組

  • where there's no director and instead we give people a rule.

    在控制組沒有指揮者, 而是我們給定了一個規則,

  • We tell them, okay, we're going to do exactly the same thing

    我們告訴他們,好吧,我們要做完全一樣的事情

  • but this time there's no director. Instead you've got to

    但這次沒有指揮者。而是你自己要記得

  • ignore objects with the dark gray background.

    去忽略掉黑灰色背景格子裡的物件。

  • You'll see that this is exactly the same condition, only

    你可以看到這是完全相同的狀況, 唯一的差別

  • in the no-director condition they just have to remember

    是在沒有指揮者的控制組, 他們只要記得

  • to apply this somewhat arbitrary rule, whereas

    用上這條多少有點隨心所欲的規則, 而在

  • in the director condition, they have to remember

    有指揮者那組, 他們必須記得

  • to take into account the director's perspective

    要考慮到指揮者的視角

  • in order to guide their ongoing behavior.

    來決定他們要進行的動作

  • Okay, so if I just show you the percentage errors

    好, 那我要讓大家看看出錯的百分比的數據

  • in a large developmental study we did,

    來自我們所進行的一個大型的發展研究

  • this is in a study ranging from age seven to adulthood,

    研究對象的年齡層從七歲到成年

  • and what you're going to see is the percentage errors

    你將會看到的是出錯的百分比

  • in the adult group in both conditions,

    在成人族群中, 實驗組與控制組的數據圖

  • so the gray is the director condition, and you see

    灰色的是有指揮者的狀況, 你可以看到

  • that our intelligent adults are making errors about 50 percent

    這些聰明的成人大概有50%的犯錯比例

  • of the time, whereas they make far fewer errors

    而他們出錯的比例相對來說低了很多

  • when there's no director present, when they just have

    在沒有指揮者的狀況下, 在他們只要

  • to remember that rule of ignoring the gray background.

    自己記得那條規則, 忽略掉灰色背景的格子

  • Developmentally, these two conditions develop

    從發展的過程來看, 兩組的發展趨勢

  • in exactly the same way. Between late childhood

    幾乎是完全相同的。從兒童期的後段,

  • and mid-adolescence, there's an improvement,

    到青春期的中段, 一直都有進步

  • in other words a reduction of errors, in both of these trials,

    換句話說, 出錯率降低了, 在兩種實驗都如此

  • in both of these conditions.

    在這兩個年齡層也都如此。

  • But it's when you compare the last two groups,

    但當您比較最後兩組數據

  • the mid-adolescent group and the adult group

    青春期中段 與 成年人

  • where things get really interesting, because there, there is

    就變得很有意思了, 因為在這兩個階段之間

  • no continued improvement in the no-director condition.

    沒有指揮者狀況下, 出錯率並沒有變低了

  • In other words, everything you need to do in order to

    換句話說,你所需要的關於去

  • remember the rule and apply it seems to be fully developed

    記住規則和應用規則的部分, 似乎已經完全發展好了

  • by mid-adolescence, whereas in contrast,

    在青春期中段之前就完成了,而相比之下,

  • if you look at the last two gray bars, there's still

    如果你看看最後兩個灰色線條,仍有

  • a significant improvement in the director condition

    很明顯的進步, 在有指揮者的部分

  • between mid-adolescence and adulthood, and what

    從 青春期 中段 到成年還是有進步

  • this means is that the ability to take into account someone

    這代表了, 把其他人的觀點列入考量

  • else's perspective in order to guide ongoing behavior,

    來導引所進行的行為的能力

  • which is something, by the way, that we do in everyday life all

    這也是我們日常生活每天都在做的事情

  • the time, is still developing in mid-to-late adolescence.

    這種能力在青春期的中段到後段仍然在發展

  • So if you have a teenage son or a daughter and you

    因此,若你剛好有十幾歲的兒子或女兒

  • sometimes think they have problems taking other people's

    而且你有時候會覺得他們不太容易接納別人的觀點

  • perspectives, you're right. They do. And this is why.

    你的感覺沒錯, 他們確實如此, 你也知道為什麼了

  • So we sometimes laugh about teenagers.

    所以我們有時候會笑青少年

  • They're parodied, sometimes even demonized in the media

    他們被醜化, 有時甚至被媒體妖魔化

  • for their kind of typical teenage behavior. They take risks,

    只因為他們的一些典型的青少年舉動,他們會冒險

  • they're sometimes moody, they're very self-conscious.

    他們有時喜怒無常,他們的自我意識很強

  • I have a really nice anecdote from a friend of mine

    我有一個朋友告訴我一個小故事

  • who said that the thing he noticed most

    我朋友說, 他所注意到

  • about his teenage daughters before and after puberty

    關於他的十幾歲的女兒, 在青春期前後最大的變化

  • was their level of embarrassment in front of him.

    是女兒在他面前受窘的程度

  • So, he said, "Before puberty, if my two daughters

    他說到, 在青春期之前, 如果我的兩個女兒

  • were messing around in a shop, I'd say, 'Hey,

    在一家店裡胡鬧, 我會說: "嘿!

  • stop messing around and I'll sing your favorite song,'

    別再胡鬧了, 我就唱一首你們最愛聽的歌"

  • and instantly they'd stop messing around and he'd sing

    而當他開始唱她們最喜歡的歌,

  • their favorite song. After puberty, that became the threat.

    女兒們馬上就停止胡鬧。而在青春期之後,這招就變成威脅了

  • (Laughter)

    (笑聲)

  • The very notion of their dad singing in public

    她們想到爸爸在公眾場合唱歌這件事

  • was enough to make them behave.

    就足以讓她們守規矩了

  • So people often ask,

    所以人們常會問,

  • "Well, is adolescence a kind of recent phenomenon?

    "嗯,青春期是最近流行的一種現象嗎?

  • Is it something we've invented recently in the West?"

    這是西方社會最近才發明出來的嗎?"

  • And actually, the answer is probably not. There are lots

    其實答案很可能是否定的。歷史上有很多

  • of descriptions of adolescence in history that sound

    關於青春期的描寫, 聽起來

  • very similar to the descriptions we use today.

    跟我們現在描寫的方式很相像。

  • So there's a famous quote by Shakespeare from "The Winter's Tale"

    在莎士比亞的《冬天的故事》有一句名言

  • where he describes adolescence as follows:

    他是這樣描寫 青春期 的:

  • "I would there were no age between ten and

    "我想, 在十歲和廿三歲之間, 是沒有年齡的

  • three-and-twenty, or that youth would sleep out the rest;

    不然年輕應該會在其餘的時間沉睡

  • for there is nothing in the between but getting wenches

    因為在這段歲月中沒有什麼事值得做, 除了讓女僕懷孕、

  • with child, wronging the ancientry, stealing, fighting." (Laughter)

    敗壞古風、 偷竊、 打架"。(笑聲)

  • He then goes on to say, "Having said that, would any

    他接著說,"儘管如此,除了這些

  • but these boiled brains of nineteen and two-and-twenty

    十九歲到廿二歲的燒壞的腦袋, 還會有什麼人