86 billion of these are neurons that process information, sense varied stimuli and make you... well, you.

其中 860 億個為處理資訊、刺激的神經元，它們組成了...你。

But are there things in every day life that reduce this count?

日常是否有些事會使我們的腦細胞減少？

What will kill your brain cells?

什麼會殺死你的腦細胞？

We used to think that the brain couldn't produce new neurons.

我們以前認為大腦無法製造新神經元。

Although neurons are stabled cell type, meaning they don't multiple themselves, we now know that new neurons are produced from neural stem cells throughout our life time.

儘管神經元為穩定細胞，也就是它們不會自己增生，我們現在已確認在這一生，神經幹細胞會不斷製造新神經元。

But this happens only in certain areas of our brain, mainly in two small regions in the forebrain.

但這只會發生在大腦的特定部位，主要是前腦的兩個小區域。

So, while we can make new neurons, brain cell death in large amounts may be dangerous and irreversible.

所以即使我們能製造新神經元，大量腦細胞死亡還是件危險且無法挽回的事。

For example, within 5 minutes of a good blow to the head, axons are compressed and calcium rushes into your neurons, which can signal a number of different pathways and enzymes to begin cell death.

舉例來說，在頭被大力撞擊的五分鐘內，軸突會被壓縮，鈣跑到神經元，這表示會有不同的化學反應與酵素使腦細胞死亡。

This may explain the confusion, lost of consciousness and sensitivity to sound or light common in a concussion.

這或許可以幫一些人解惑說為什麼受到衝擊時總是會對聲音或光線失去反應。

Getting enough zs?

有足夠的睡眠嗎？

Although the brain can react against short term sleep deprivation, a 2014 study showed too many all-nighters may be killing neurons in the locus coeruleus.

雖然大腦可以抵抗短期的睡眠不足，一個 2014 年的研究顯示許多整夜不睡的人可能會對藍斑核的神經元造成傷害。

This is a region of the brain responsible for coordinating motivation and maintaining attention and arousal.

藍班核是大腦中負責調節動機水平、保持注意力與情感刺激的部位。

And after extended wake periods we become unable to make important proteins to keep these neurons alive.

過長的清醒時間後，我們會無法製造足夠的蛋白質來使這些神經元維生。

But don't stress about that, literally.

但也不用太擔心，真的。

Long term stress has been associated with damage to our hippocampus and a reduced ability to make new neurons.

長期壓力被認為與海馬迴的受損有關，也會影響製造新神經元的能力。

Which may explain why extreme stress can lead to numerous mental illnesses like depression, anxiety, PTSD and schizophrenia.

這也解釋了為何極度高壓會導致數種心理疾病如憂鬱症、躁鬱症、創傷後壓力症候群與精神分裂症。

Nicotine affects the hippocampus as well.

尼古丁也會影響海馬迴。

Cutting the creation of new neurons by 50% while also increasing cell death.

使新神經元的生長減少 50%，且增加細胞的死亡。

Like the smell of gasoline or permanent markers?

喜歡汽油或麥克筆的味道嗎？

Although they don't cause brain damage directly, some of the chemicals in them are as asphyxiants, meaning it will despise oxygen from the air you breathe and deprive your tissues of oxygen!

雖然它們不會直接對大腦造成傷害，但某些成分有窒息性，意思是它們會剝奪你呼吸與組織中的氧氣。

Ultimately killing brain cells.

最後殺死腦細胞。

Carbon monoxide, commonly released from stoves, furnaces, grills and cars, works the same way.

一氧化碳，常從爐子、火爐、烤架與汽車中釋放出來，也會造成同樣的傷害。

By hijacking your hemoglobin which normally carries oxygen in your blood, cells in major organs, like the brain and heart, will suffocate and die heightened of levels.

它們會劫持負責在重大器官間運輸氧氣的血紅素，讓大腦或心臟等器官窒息甚至死亡。

But what about alcohol?

那酒精呢？

It appears that short term exposure to alcohol doesn't kill brain cells!

看來短暫接觸酒精不會殺死腦細胞！

But... It can reduce communication between them.

但...會遲緩它們之前的溝通。

And over a longer period, chronic alcohol consumption can activate immune cells in the brain to produce pro inflammatory chemicals and free radicals that can lead to cell death.

但長期飲酒會刺激大腦中的免疫細胞製造抗發炎物質與自由基，而這會導致細胞死亡。

Alcoholics can also develop a B-vitamin thiamine deficiency called Wernicke-Korsakoff syndrome which can kill off brain cells and lead to memory problems, amnesia and lack of muscle coordination.

酒精也會導致維他命 B1 的缺陷，又稱魏尼克腦病，此病會殺死腦細胞並導致記憶問題、失憶與肌肉不協調。

Taking a break from drinking may be the best way to promote neural stem cell growth and other factors from neurogenesis.

休息不喝酒或許是促進神經幹細胞生長或其他幫助神經元的最好辦法。

But no matter how much we might fear losing brain cells, we might have no choice in the matter.

但不論多努力要防止腦細胞死亡，我們可能毫無選擇。

Our brain declines by 5% of its volume per weight per decade after the age of 40 with the rate increasing around the age of 70.

從四十歲起，我們的腦容量會每十年減少百分之五，而七十歲後會更嚴重。

Most widely experienced is memory loss which can be a normal part of aging.

最常見的後果是記憶喪失，這也是老化的常見症狀之一。

Overall, we shouln't be kept a night wondering how many brain cells we lost today as losing them may be a sign that things are alright.

總之，我們不該整夜不睡想著多少腦細胞死去了，因為有時這或許是一切安好的象徵。

During development we produce many more neurons than we need and brain cells have to die to maintain the brain's complex organization.

人類發展以來，我們製造了比需求還多的神經元，所以一些腦細胞得死去來維持大腦的複雜平衡。

Research in rats suggest that we lose neurons in our prefontal cortex as a way of reorganizing our brain during and after puberty.

在白老鼠實驗中，我們發現失去前額葉皮質的神經元是在青春期中與後調整大腦的方式。

More neurons doesn't necessarily make for a better or a smarter person, and sometimes cell death makes for a healthy life.

比較多的神經元不代表人會比較聰明或比較好，且有時細胞死亡反而對健康有益。

Thank you so much to Science Sam for narrating this video.

感謝 Science Sam 為這部影片旁白。

You need to follow her on instagram @science.sam.

請去追蹤她的 IG @science.sam。

She'll make you really inspired by science and also even more interested in your brain.

她會啟蒙你對科學的興趣，甚至讓你對自己的大腦有興趣。

Know what doesn't kill your brain cells?

知道什麼不會傷害你的腦細胞嗎？

Podcasts!

線上廣播節目！

So you should listen to ours.

你應該聽聽看我們的節目。

We've just released our first ever live podcast from Just For Laughs in Montreal.

我們才剛在蒙特婁發布第一部線上廣播。

We were super nervous, I think we pulled it off.

我們超緊張，但我覺得我們做得很好。

Let us know what do you think using the hashtag #SidenotePodcast.

在下方用 #SidenotePodcast 讓我們知道你的想法。

And we'll see you next week for a new science video.

我們下週見，請期待新的科學影片。

Peace.

再見。