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  • As far as we know,

    據我們了解,

  • there's only one thing in our solar system sophisticated enough to study itself:

    太陽系中有個東西非常精密,

  • the human brain.

    精密到要自我研究:

  • But this self-investigation is incredibly challenging;

    人類的大腦。

  • a living brain is shielded by a thick skull,

    但這自我探索的挑戰性非常高:

  • swaddled in layers of protective tissue,

    活體大腦被很厚的顱骨保護著,

  • and made up of billions of tiny, connected cells.

    有數層保護組織包裹著,

  • That's why it's so difficult to isolate, observe, and understand diseases

    且大腦由數億細小、 互相連接的細胞所組成

  • like Alzheimer's.

    因此,我們很難分離、 觀察並瞭解疾病

  • So how do we study living brains without harming their owners?

    如阿茲海默症。

  • We can use a trio of techniques called EEG,

    那我們要如何研究活體大腦 而不傷害它的主人呢?

  • fMRI,

    我們能用三種技術, 分別叫 EEG、

  • and PET.

    fMRI

  • Each measures something different and has its own strengths and weaknesses,

    及 PET 。

  • and we'll look at each in turn.

    它們測量的東西不同, 且各有優缺點,

  • First is EEG, or electroencephalography,

    我們一項一項看。

  • which measures electrical activity in your brain.

    首先是 EEG ,又稱「腦電圖」,

  • As brain cells communicate, they produce waves of electricity.

    它偵測大腦的電訊號。

  • Electrodes placed on the skull pick up these waves,

    腦細胞傳送訊息時會製造電波,

  • and differences in the signals detected between electrodes

    由放在顱骨上的電極接收;

  • provide information about what's happening.

    電極接收到不同的訊號,

  • This technique was invented almost 100 years ago,

    能提供資訊,看發生什麼事了。

  • and it's still used to diagnose conditions like epilepsy and sleep disorders.

    這項技術近百年前就發明了,

  • It's also used to investigate what areas of the brain are active

    至今仍被使用在鑑別診斷上, 如癲癇和睡眠障礙;

  • during learning or paying attention.

    它也被用在偵測大腦哪些區域

  • EEG is non-invasive,

    在學習或專注時是活化的。

  • relatively inexpensive,

    EEG 沒有侵入性、

  • and fast:

    相對便宜

  • it can measure changes that occur in just milliseconds.

    且能迅速反應:

  • Unfortunately, it's hard to determine

    它能偵測毫秒間的變化。

  • exactly where any particular pattern originates.

    然而不幸的是,

  • Electrical signals are generated constantly all over the brain

    它很難精準定位 特定波型特徵的來源。

  • and they interact with each other to produce complex patterns.

    電訊號一直在大腦中產生,

  • Using more electrodes or sophisticated data-processing algorithms can help.

    而大腦用此方式傳遞訊息, 製造出複雜的波型特徵。

  • But in the end, while EEG can tell you precisely when certain activity occurs,

    用更多電極,或建立複雜函數 來解讀檔案有幫助,

  • it can't tell you precisely where.

    但最後,僅管 EEG 能告訴你 特定活動何時產生,

  • To do that, you'd need another technique,

    卻無法精確說出在哪產生。

  • such as functional magnetic resonance imaging, or fMRI.

    為此,你需要另一個技術,

  • fMRI measures how quickly oxygen is consumed by brain cells.

    例如「功能性磁振造影」, 又稱 fMRI 。

  • Active areas of the brain use oxygen more quickly.

    fMRI 偵測腦細胞 消耗氧氣的速率,

  • So watching an fMRI scan while a person completes cognitive or behavioral tasks

    大腦活化區域耗氧速度較快,

  • can provide information about which regions of the brain might be involved.

    因此當某人完成認知 或行為上的任務時,

  • That allows us to study everything from how we see faces

    fMRI 可以提供大腦哪些部分 參與任務的資訊。

  • to how we understand what we're feeling.

    這使我們能研究所有事情, 從如何觀察人臉

  • fMRI can pinpoint differences in brain activity to within a few millimeters,

    到如何理解自己的感受。

  • but it's thousands of times slower than EEG.

    fMRI 能定位腦部活動, 其精準度在數毫米間,

  • Using the two techniques together

    但時間比 EEG 慢數千倍。

  • can help show when, and where, neural activity is occurring.

    同時使用這兩個技術

  • The third, even more precise, technique is called positron emission tomography

    能幫助我們了解,神經活動 開始的時間和位置。

  • and it measures radioactive elements introduced into the brain.

    第三個技術則更精確,叫做 「正子發射斷層掃描( PET )」,

  • That sounds much scarier than it actually is;

    它能測量事先注入 大腦的放射性物質,

  • PET scans, like fMRI and EEG, are completely safe.

    這聽起來比實際上來得可怕,

  • During a PET scan, a small amount of radioactive material called a tracer

    然 PET 跟 fMRI 和 EEG 一樣 完全安全。

  • is injected into the bloodstream,

    在 PET 掃描期間,少量 放射線物質稱作示蹤劑

  • and doctors monitor its circulation through the brain.

    會被注入血液,

  • By modifying the tracer to bind to specific molecules,

    然後醫師會偵測血流到大腦。

  • researchers can use PET to study the complex chemistry in our brains.

    透過修改示蹤劑來結合特定分子,

  • It's useful for studying how drugs affect the brain

    研究者可以用 PET 來研究 腦部複雜的化學分子。

  • and detecting diseases like Alzheimer's.

    在研究藥物如何影響大腦

  • But this technique has the lowest time resolution of all

    及偵測疾病如阿茲海默症上,這很有用。

  • because it takes minutes for the tracer to circulate and changes to show up.

    但這技術所花時間最久,

  • These techniques collectively help doctors and scientists

    因為要數分鐘,示蹤劑才會 流到腦部,變化才會顯現。

  • connect what happens in the brain with our behavior.

    這些科技共同幫助醫師和科學家了解,

  • But they're also limited by how much we still don't know.

    行為和大腦發生的事 如何連結起來,

  • For example, let's say researchers are interested in studying how memory works.

    但它們也受到我們知識有限的限制,

  • After asking 50 participants to memorize a series of images while in MRI scanners,

    例如,研究者想知道記憶如何運作,

  • the researchers might analyze the results

    使用 fMRI ,在問過五十個 受試者記下一系列的圖片後,

  • and discover a number of active brain regions.

    研究者可以分析結果,

  • Making a link between memory and specific parts of the brain

    並發現一些腦部活化區域,

  • is an important step forward.

    發現記憶和腦部特定區域相關

  • But future research would be necessary

    是重要的一步,

  • to better understand what's happening in each region,

    但未來的研究需要

  • how they work together,

    更理解每個區域發生什麼事、

  • and whether the activity is because of their involvement in memory

    它們如何協同工作

  • or another process occurring simultaneously.

    及這些活化訊號,

  • More advanced imaging and analysis technology

    是因為參與記憶過程,

  • might one day provide more accurate results

    還是其他同時發生的過程。

  • and even distinguish

    更先進的影像及分析技術

  • the activity of individual neurons.

    有天或許能提供更準確的結果,

  • Until then, our brains will keep measuring, analyzing, and innovating

    或甚至區分個別神經元的活動。

  • in pursuit of that quest to understand

    在那之前,我們的大腦會 繼續測量、分析和創新,

  • one of the most remarkable things we've ever encountered.

    為追求完全理解

As far as we know,

據我們了解,

字幕與單字

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B1 中級 中文 美國腔 TED-Ed 大腦 偵測 腦部 活化 技術

【TED-Ed】腦部掃描是怎麼運作的?(How do brain scans work? - John Borghi and Elizabeth Waters)

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    Samuel 發佈於 2018 年 05 月 18 日
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