As you go through life, your body changes radically.

人的一生中，身體會發生翻天覆地的變化。

Inside your head, your most complex organ is constantly transforming too, beginning work before you're born, and continuing even after you've been declared dead.

在你的大腦中，你最複雜的器官也在不斷變化，在你出生前就開始工作，甚至在你被宣佈死亡後仍在繼續。

This is the life cycle of your brain.

這就是大腦的生命週期。

Your brain starts to form about two weeks after conception.

受孕兩週後，大腦開始形成。

On one side of the developing embryo, the cells thicken to form what is called the neural plate.

在發育中胚胎的一側，細胞增厚形成所謂的神經板。

Around week four, this folds over onto itself, forming a tube which ultimately creates the nervous system.

大約在第四周，它摺疊起來，形成一個管子，最終形成神經系統。

Every minute from the time the neural tube closes, your brain is growing hundreds of nerve cells called neurons.

從神經管閉合開始，大腦每分鐘都在生長數百個神經細胞，這些細胞被稱為神經元。

At birth, your brain contains about 100 billion neurons, more than an adult.

剛出生時，大腦中約有 1,000 億個神經元，比成年人還多。

This gives the baby the best chance of developing a healthy brain.

這能為嬰兒提供發育健康大腦的最佳機會。

The excess neurons are shed before you become an adult.

多餘的神經元會在成年前脫落。

But what you don't have is a lot of synapses, the point of contact where electronic signals are passed between neurons, which in turn change the behaviour of the neurons.

但你沒有的是大量的突觸，突觸是神經元之間傳遞電子信號的接觸點，而電子信號又會改變神經元的行為。

Some neurons become insulated by a fatty substance called myelin.

一些神經元被一種名為髓鞘的脂肪物質絕緣。

These neurons, known as white matter, are able to transmit information faster between brain areas, allowing more complex processes to take place.

這些被稱為 "白質 "的神經元能夠在腦區之間更快地傳遞信息，從而使更復雜的過程得以進行。

When you're born, the average number of synapses per neuron is 2,500.

當你出生時，每個神經元的突觸數量平均為 2,500 個。

But that increases to approximately 15,000 per neuron over the first few years of your life, as your neurons mature and create new synapses.

但在生命的最初幾年，隨著神經元發育成熟併產生新的突觸，每個神經元的突觸數量會增加到大約 15000 個。

The speed at which they form synapses could be one reason children find it easier to learn things like languages or musical instruments.

他們形成突觸的速度可能是兒童更容易學習語言或樂器的原因之一。

It's also why children's experiences in this phase can have lasting effects on their development.

這也是為什麼兒童在這一階段的經歷會對他們的成長產生持久影響的原因。

From age 3 until about 10, your brain starts to remove connections it no longer needs.

從 3 歲到 10 歲左右，大腦開始移除它不再需要的連接。

Neuroscientists used to think all synapses worked at a constant, fixed level.

神經科學家曾經認為，所有突觸都在一個恆定的水準上工作。

But now they understand that synapses can be strengthened or weakened depending on how they are used.

但現在他們明白了，突觸可以根據使用方式的不同而加強或減弱。

This is known as neuroplasticity.

這就是所謂的神經可塑性。

It's essentially your brain's way of making sure it's more efficient with experience and absorbs new information.

從本質上講，這是你的大腦確保更有效地積累經驗和吸收新資訊的一種方式。

If you're enjoying this film and want to read more of our coverage, why not take out a subscription to The Economist?

如果您喜歡這部電影，並希望閱讀我們更多的報道，為什麼不訂閱《經濟學人》呢？

You'll receive daily and weekly analysis of global affairs.

您將收到每日和每週的全球事務分析。

You can read us online, in the app, or listen to the audio edition.

您可以在線閱讀、使用應用程序或收聽音頻版。

For the best offer, click the link.

請點擊鏈接獲取最佳優惠。

By the time you become a teenager, your brain has stopped growing, but it continues to develop.

到了青少年時期，大腦已經停止生長，但仍在繼續發育。

The insulation of the neurons, which begins at birth, continues over many years.

神經元的絕緣始於出生，並持續多年。

It starts at the back of the brain and moves forward, so different parts of your brain develop at different rates.

它從大腦後部開始向前發展，是以大腦不同部位的發育速度不同。

Areas associated with reward, like the ventral striatum, develop faster than the prefrontal cortex, which is linked to self-control and rationality.

與獎賞有關的區域，如腹側紋狀體，比與自我控制和理性有關的前額葉皮層發育得更快。

Teens also experience major changes in their limbic system, the part of the brain that controls emotions.

青少年的邊緣系統（大腦中控制情緒的部分）也會發生重大變化。

All this might explain why teenagers experience more mood swings than adults.

這一切或許可以解釋為什麼青少年比成年人更容易情緒波動。

Neuroscientists believe the difference in development between the emotion-driven part of the brain and the rational part may also be the reason teenagers are more likely to take risks or experience addiction compared with adults.

神經科學家認為，大腦情感驅動部分和理性部分在發育上的差異也可能是青少年比成年人更容易冒險或上癮的原因。

Puberty also brings with it increased activity in the ventromedial prefrontal cortex, the part of the brain that relates to self-evaluation.

青春期也會使大腦中與自我評價有關的腹內側前額葉皮層的活動增加。

This change can improve teenagers' understanding of social interactions and their ability to form friendships.

這種變化可以提高青少年對社會交往的理解和建立友誼的能力。

But it might also make them more susceptible to social anxiety.

但這也可能使他們更容易患上社交焦慮症。

Post-puberty, the brain continues to develop.

青春期後，大腦繼續發育。

Brain tissue in the prefrontal cortex increases connections, joining the emotional and motor centres.

前額葉皮層的腦組織會增加連接，將情感中樞和運動中樞連接起來。

Your brain reaches full development by your 30s, and white matter reaches the highest volume at about 40.

大腦在 30 多歲時發育完全，白質在 40 歲左右達到最高容量。

But it's not all downhill from there.

不過，事情並非就此一帆風順。

As you age, plasticity allows your brain to keep changing and adapting.

隨著年齡的增長，可塑性會讓大腦不斷變化和適應。

Research has shown older adults are more likely to use both sides of the brain for short-term memory, rather than just the left brain hemisphere.

研究表明，老年人更傾向於使用大腦兩側進行短期記憶，而不僅僅是左腦半球。

Middle-aged brains have also learnt to minimise the negative.

中年人的大腦也學會了儘量減少負面影響。

Scientists have found the amygdala, the part of the brain that deals with emotion, lights up when younger people look at both positive and negative images.

科學家們發現，當年輕人看到正面和負面影像時，大腦中負責處理情緒的杏仁核會亮起來。

But for older adults, it reacts much less when shown negative images.

但對於老年人來說，當看到負面影像時，他們的反應要小得多。

This might be because as you age, you become more resilient.

這可能是因為隨著年齡的增長，人的復原力會越來越強。

Decades of experience in dealing with difficult situations activates neural pathways, which can be used when you experience a similar situation.

數十年應對困境的經驗會激活神經通路，當你遇到類似情況時，就可以利用這些神經通路。

For those who go through the menopause, changes to the amount of estrogen affect brain energy consumption, producing symptoms like hot flushes and mood swings.

對於更年期的人來說，雌激素量的變化會影響大腦的能量消耗，產生潮熱和情緒波動等症狀。

The volume of white matter also falls, and doesn't recover.

白質的體積也會下降，而且不會恢復。

But despite this, those who are post-menopausal have higher structural connectivity between some brain regions than those who don't go through the menopause, meaning that the connections in those regions may become more efficient.

但儘管如此，絕經後的人與未絕經的人相比，某些腦區之間的結構連接性更高，這意味著這些腦區的連接可能變得更有效。

The point at which your brain begins to slow down depends on your genes, but on the whole, studies show that the slowing process begins in your 30s and 40s, before accelerating in your 60s and 70s.

大腦開始變慢的時間取決於你的基因，但總的來說，研究表明，大腦變慢的過程始於 30 多歲和 40 多歲，然後在 60 多歲和 70 多歲時加速。

As you move into later life, your cerebral cortex, which is the outer layer of the brain, thins.

進入晚年後，大腦皮層（即大腦外層）會逐漸變薄。

This is particularly noticeable in the frontal lobe and the hippocampus, which are important for memory, emotions and navigation.

這在對記憶、情緒和導航非常重要的額葉和海馬體中尤為明顯。

Your white matter shrinks, and the brain generates fewer chemical messengers, such as dopamine and serotonin, which leads to slower cognitive processing.

你的白質會萎縮，大腦產生的多巴胺和血清素等化學信使也會減少，從而導致認知處理過程變慢。

Until very recently, neuroscientists didn't know what happens to your brain when you die.

直到最近，神經科學家還不知道人死後大腦會發生什麼變化。

But by chance, doctors were recording the brainwaves of a patient when he died of a heart attack.

但一次偶然的機會，醫生在記錄一名因心臟病發作而死亡的病人的腦電波時發現了這一現象。

They found a change in a specific band of brainwaves involved in high cognitive functions, such as concentrating, dreaming and memory retrieval.

他們發現，涉及高度認知功能的特定腦電波波段發生了變化，如集中注意力、做夢和記憶檢索。

Suggesting that just before you die, your brain may recall important life events, which may explain why those who have near-death experiences report seeing their lives flash before them.

這表明，在臨死前，大腦可能會回憶起生命中的重要事件，這或許可以解釋為什麼那些有瀕死體驗的人報告說看到自己的生命在眼前閃過。

And your brain doesn't stop working, even when you're dead.

即使你死了，大腦也不會停止工作。

Some studies have found that brain activity may continue for several minutes, even after your heart has stopped.

一些研究發現，即使在心臟停止跳動後，大腦活動仍會持續幾分鐘。