The science of imagination - Andrey Vyshedskiy

838,786 views ・ 2016-12-12

TED-Ed


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譯者: Chen-Ching Teng 審譯者: Ellen Tung
00:07
Imagine, for a second, a duck teaching a French class,
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花個幾秒鐘想像一下 一隻鴨子在教法文課
00:11
a ping-pong match in orbit around a black hole,
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一場在黑洞旁軌道上的乒乓球賽
00:15
a dolphin balancing a pineapple.
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一隻海豚試圖平衡一顆鳳梨
00:17
You probably haven't actually seen any of these things,
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你也許從沒看過剛剛的任何一樣東西
00:21
but you could imagine them instantly.
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但你可以立刻想像出他們
00:23
How does your brain produce an image of something you've never seen?
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你的大腦是怎麼產生出一張 你從沒看過東西的畫面呢?
00:27
That may not seem hard,
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那似乎不是太困難
00:28
but that's only because we're so used to doing it.
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但那只是因為我們 非常習慣於這件事了
00:31
It turns out that this is actually a complex problem
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這實際上是個複雜的問題
00:34
that requires sophisticated coordination inside your brain.
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你的大腦中需要複雜的協調合作
00:38
That's because to create these new, weird images,
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創造出這些新奇的畫面
00:41
your brain takes familiar pieces and assembles them in new ways,
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你的大腦需要取出相近的片段 再將他們用不同的方式組合起來
00:46
like a collage made from fragments of photos.
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就像利用各部份相片 完成一幅拼貼畫作
00:49
The brain has to juggle a sea of thousands of electrical signals
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大腦必須應付海一般 成千上萬的電子訊號
00:53
getting them all to their destination at precisely the right time.
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並在準確的時間點 將他們放到各自的目的地
00:58
When you look at an object,
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當你看著一樣東西
00:59
thousands of neurons in your posterior cortex fire.
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後皮質裡上千個神經元正受到激發
01:03
These neurons encode various characteristics of the object:
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這些神經元編碼出 各種關於這樣東西的特性:
01:06
spiky, fruit, brown, green, and yellow.
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帶刺的、水果、咖啡色、綠色和黃色
01:11
This synchronous firing strengthens the connections between that set of neurons,
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這個同步激發使得 那些神經元彼此間的連結更強
01:15
linking them together into what's known as a neuronal ensemble,
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讓他們結成了我們所知道的神經元集群
01:20
in this case the one for pineapple.
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鳳梨這個例子中
01:22
In neuroscience, this is called the Hebbian principle,
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在神經科學裡稱之為赫布理論
01:25
neurons that fire together wire together.
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一同受到激發的神經元會連結在一起
01:28
If you try to imagine a pineapple later,
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假設過了一下子 你試圖去想像一個鳳梨
01:30
the whole ensemble will light up, assembling a complete mental image.
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整個集群會亮起來 並組合出一個完整的心理意象
01:35
Dolphins are encoded by a different neuronal ensemble.
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海豚則會由不同神經元集群來編碼
01:39
In fact, every object that you've seen
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事實上,你看到的每一樣物品
01:41
is encoded by a neuronal ensemble associated with it,
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皆由一個神經元集群 來產生與它相關的編碼
01:45
the neurons wired together by that synchronized firing.
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藉由同時受到激發 而使那些神經元連結在一起
01:49
But this principle doesn't explain the infinite number of objects
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然而這個理論並無法解釋 我們如何想像出無限多種物品
01:52
that we can conjure up in our imaginations without ever seeing them.
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即使我們從未見過那些東西
01:57
The neuronal ensemble for a dolphin balancing a pineapple doesn't exist.
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「一隻海豚試圖平衡鳳梨」 這樣的神經元集群並不存在
02:02
So how come you can imagine it anyway?
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那麼,你為什麼能想像這個畫面呢?
02:04
One hypothesis, called the Mental Synthesis Theory,
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有一個假說叫「心理合成理論」
02:07
says that, again, timing is key.
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又再次重申了關鍵在於時間點
02:11
If the neuronal ensembles for the dolphin and pineapple
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如果海豚與鳳梨的兩個神經元集群
02:13
are activated at the same time,
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同時受被激發
02:16
we can perceive the two separate objects as a single image.
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我們便能在同一畫面中 感知到兩個不同物品
02:20
But something in your brain has to coordinate that firing.
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但必須由你大腦中的某樣東西 來協調這樣的激發
02:24
One plausible candidate is the prefrontal cortex,
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最有可能的角色就是前額皮質
02:27
which is involved in all complex cognitive functions.
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因為它幾乎參與了 所有複雜的認知行為
02:31
Prefrontal cortex neurons are connected to the posterior cortex
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前額皮質中的神經元 與後皮質連結在一起
02:35
by long, spindly cell extensions called neural fibers.
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藉由長且纖細的細胞延伸 稱之為神經纖維
02:40
The mental synthesis theory proposes that like a puppeteer pulling the strings,
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心理合成理論認為 如同木偶師操縱著繩子
02:44
the prefrontal cortex neurons send electrical signals
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前額皮質神經元傳送出電子訊號
02:47
down these neural fibers
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沿著那些神經纖維
02:49
to multiple ensembles in the posterior cortex.
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抵達數個後皮質中的神經元集群
02:53
This activates them in unison.
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使得他們行為一致
02:56
If the neuronal ensembles are turned on at the same time,
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若那些神經元群集 能夠在同時受到激發
02:59
you experience the composite image just as if you'd actually seen it.
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你就如真的看見一般 想像出合成畫面
03:04
This conscious purposeful synchronization
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這個感知有目的的藉由前額皮質
03:06
of different neuronal ensembles by the prefrontal cortex
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使得數個神經元集群達成同步
03:09
is called mental synthesis.
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稱之為心理合成
03:12
In order for mental sythesis to work,
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為了使它順利運作
03:13
signals would have to arrive at both neuronal ensembles at the same time.
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訊號必須同時抵達神經元集群
03:19
The problem is that some neurons
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會出現的問題是
03:21
are much farther away from the prefrontal cortex than others.
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有些神經元比其他 前額皮質中的神經元遠的多
03:25
If the signals travel down both fibers at the same rate,
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如果訊號以同樣速度 在神經纖維中傳輸
03:28
they'd arrive out of sync.
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他們並無法同時到達
03:31
You can't change the length of the connections,
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你無法改變連結的長度
03:33
but your brain, especially as it develops in childhood,
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但你的大腦,特別是在孩童發展階段
03:37
does have a way to change the conduction velocity.
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的確有辦法改變傳導速度
03:40
Neural fibers are wrapped in a fatty substance called myelin.
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神經纖維外層包裹著 富含脂肪的物質稱為髓鞘
03:45
Myelin is an insulator
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髓鞘是一種絕緣體
03:47
and speeds up the electrical signals zipping down the nerve fiber.
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可以加快電子訊號 在神經纖維中的傳送速度
03:51
Some neural fibers have as many as 100 layers of myelin.
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有些神經纖維外甚至包著 100 層之多的髓鞘
03:55
Others only have a few.
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其他的則數量較少
03:57
And fibers with thicker layers of myelin
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那些包裹著較厚髓鞘層的神經纖維
04:00
can conduct signals 100 times faster or more
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相較於沒那麼厚的神經纖維
04:04
than those with thinner ones.
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傳導速度可達到或超過 100 倍
04:06
Some scientists now think that this difference in myelination
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部份科學家開始認為 這些髓鞘層的厚薄程度
04:09
could be the key to uniform conduction time in the brain,
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也許就是平衡大腦中傳導時間的關鍵
04:13
and consequently, to our mental synthesis ability.
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所以,對於我們心理合成的能力
04:16
A lot of this myelination happens in childhood,
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大部分的髓鞘生長於孩童時期
04:20
so from an early age,
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因此小時候
04:21
our vibrant imaginations may have a lot to do with building up brains
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我們活躍的想像力 對於建構大腦有很大的作用
04:26
whose carefully myelinated connections
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有著髓鞘良好發展的連結
04:28
can craft creative symphonies throughout our lives.
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能作出富有創造力的生命樂章
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