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