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  • Imagine that day by day,

    想像一下

  • your field of vision becomes slightly smaller,

    你的視野一天比一天小

  • narrowing or dimming

    越來越狹窄或模糊

  • until eventually you go completely blind.

    直到你完全看不見

  • We tend to think of blindness as something you're born with,

    我們總是認為失明是天生的

  • but in fact, with many diseases like Retinitis pigmentosa

    事實上很多疾病像是 色素性視網膜炎

  • and Usher syndrome,

    和尤塞氏綜合症等疾病

  • blindness can start developing when you're a kid,

    視力會從小開始退化

  • or even when you're an adult.

    或甚至在成人期開始

  • Both of these rare genetic diseases affect the retina,

    二種少數的遺傳疾病會影響視網膜

  • the screen at the back of the eye that detects light and helps us see.

    視網膜在眼睛後方 用來感受光線形成視覺

  • Now imagine if the eye could regenerate itself

    想像一下眼睛若能自動復原

  • so that a blind person could see again.

    那麼盲人就能重見光明了

  • To understand if that's possible, we need to grasp how the retina works

    要了解其可行性 要先窺探視網膜的運作

  • and what it has to do with a multitalented creature

    和多樣化生物斑馬魚又有何關聯

  • named the zebrafish.

    人類的視網膜由不同細胞層組成

  • The human retina is made of different layers of cells,

    在眼睛後方有特殊的神經細胞

  • with special neurons that live in the back of the eye

    為視桿及視錐的感光細胞

  • called rod and cone photoreceptors.

    感光細胞將吸收的光線轉換成

  • Photoreceptors convert the light coming into your eye

    大腦訊號並形成影像

  • into signals that the brain uses to generate vision.

    尤塞氏綜合症和 色素性視網膜炎的患者

  • People who have Usher syndrome and retinitis pigmentosa

    感光細胞會逐步退化

  • experience a steady loss of these photoreceptors

    最後視網膜無法偵測光線

  • until finally that screen in the eye can no longer detect light

    也不能傳遞訊號到大腦

  • nor broadcast signals to the brain.

    不像大多的身體細胞一樣

  • Unlike most of your body's cells, photoreceptors don't divide and multiply.

    感光細胞無法分裂和複製

  • We're born with all the photoreceptors we'll ever have,

    人的感光細胞數量始終如一

  • which is why babies have such big eyes for their faces

    這是為什麼寶寶的眼睛看起來較大

  • and part of why they're so cute.

    也是他們這麼可愛的原因

  • But that isn't the case for all animals.

    但不是所有的動物都是如此

  • Take the zebrafish, a master regenerator.

    以再生專家斑馬魚為例

  • It can grow back its skin, bones, heart and retina after they've been damaged.

    魚皮、魚骨、心臟和 視網膜在受損後都能再生

  • If photoreceptors in the zebrafish retina are removed or killed by toxins,

    如果其視網膜的感光細胞 因有害物質而消失

  • they just regenerate and rewire themselves to the brain to restore sight.

    只要自行再生感光細胞就能回復視力

  • Scientists have been investigating this superpower

    科學家一直在研究其超能力

  • because zebrafish retina are also structured very much like human retina.

    因斑馬魚和人的視網膜結構非常相似

  • Scientists can even mimic the effects of disorders like Usher syndrome

    科學家甚至能在斑馬魚的眼睛模擬 尤塞氏綜合症

  • or retinitis pigmentosa on the zebrafish eye.

    或色素性視網膜炎等病症

  • This allows them to see how zebrafish go about repairing their retinas

    這能讓他們研究 斑馬魚如何修復感光細胞

  • so they might use similar tactics to fix human eyes one day, too.

    或許某天人類的視力 也能用類似的方式復原

  • So what's behind the zebrafish's superpower?

    那斑馬魚超能力的秘密是什麼?

  • The main players are sets of long cells that stretch across the retina

    主要機制在於 視網膜內的放射狀細胞

  • calledller glia.

    名為米勒神經膠質細胞

  • When the photoreceptors are damaged, these cells transform,

    當感光細胞受損時 此細胞會產生變化

  • taking on a new character.

    去執行新任務

  • They become less likeller cells and more like stem cells,

    米勒神經膠質細胞會變得像幹細胞

  • which can turn into any kind of cell.

    可分化成任何細胞

  • Then these long cells divide,

    這些放射狀細胞能分裂

  • producing extras that will eventually grow into new photoreceptors,

    製造新細胞 進而生成新的感光細胞

  • travel to the back of the eye and rewire themselves into the brain.

    重回視網膜並重新連結大腦

  • And now some researchers even think they've found the key to how this works

    有些研究員甚至認為 已找到其運作的關鍵

  • with the help of one of two chemicals that create activity in the brain

    在於促進大腦活化其中二種化學物質

  • called glutamate and aminoadipate.

    為麩胺酸和氨基乙二酸

  • In mouse eyes,

    在老鼠的眼睛裡

  • these make theller glia divide and transform into photoreceptors,

    這讓米勒神經膠質細胞 分裂並分化為感光細胞

  • which then travel to the back of the retina,

    接著重回視網膜後方

  • like they're replenishing a failing army with new soldiers.

    有如老弱殘兵的軍隊加入了生力軍

  • But remember, none of this has happened in our retinas yet,

    請記得這些都未發生在我們的視網膜

  • so the question is how do we trigger this transformation of theller glia

    問題在於我們要如何讓 米勒神經膠質細胞

  • in the human eye?

    在人類眼睛裡分化?

  • How can we fully control this process?

    我們要如何完全掌控這個過程

  • How do photoreceptors rewire themselves into the retina?

    要怎麼讓感光細胞和 視網膜再連接在一起

  • And is it even possible to trigger this in humans?

    能不能適用於人類?

  • Or has this mechanism been lost over time in evolution?

    或是這機制已隨演化消失

  • Until we tease apart the origins of this ability,

    在我們釐清來龍去脈前

  • retinal regeneration will remain a mysterious superpower

    視網膜再生會一直是斑馬魚的

  • of the common zebrafish.

    神秘超能力

Imagine that day by day,

想像一下

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B2 中高級 中文 美國腔 TED-Ed 細胞 視網膜 再生 眼睛 神經

【TED-Ed】看不見的眼睛能否再生? (Could a blind eye regenerate? - David Davila)

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    稲葉白兎 發佈於 2015 年 06 月 25 日
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