如果你有第二個大腦會怎樣？：英語精讀講義

The brain.

大腦。

Every time you think, feel, or perform a multitude of unconscious processes, 講解

每當你思考、感受，或進行大量無意識活動時，

the 100 billion neurons in your skull conduct electrical signals to communicate and carry messages between them,

你顱骨內的1000億個神經元就會傳導電訊號，彼此溝通、傳遞訊息，

ultimately creating, well, you and everything you do. 文法

最終造就了——嗯——你，以及你所做的一切。

It's the most complex,

它是人體內最複雜、

essential, and identifiable organ in the body,

最不可或缺、也最具辨識度的器官，

acting as the center of the nervous system in all vertebrates. 片語搭配

是所有脊椎動物神經系統的中樞。

But what if how you think and feel 文法

但如果你的思考與感受

isn't just controlled by the brain and central nervous system, 文法

並不只是由大腦和中樞神經系統控制，

but in fact a second brain that you didn't know about? 慣用語

而其實還受到一個你從未察覺的「第二大腦」控制呢？

The brain uses the vagus nerve to connect and communicate with many parts of the body, 文化背景

大腦透過迷走神經與身體許多部位連接、溝通，

including the vocal cords,

包括聲帶、

heart, lungs, and most of the digestive tract.

心臟、肺，以及大部分消化道。

It also uses this nerve to convey fight or flight messages to the body, 用詞

它也會透過這條神經，把「戰鬥或逃跑」的訊息傳給身體，

which explains why you might experience a cracking voice, 表達脈絡

這就解釋了為什麼你可能會聲音顫抖、

racing heart, shortness of breath, 用詞

心跳加速、呼吸急促，

and a knot in your stomach when you're really stressed or nervous. 慣用語

並在壓力很大或非常緊張時，感覺胃揪成一團。

But while this extensive network is constantly sending signals from the brain to your body, 文法

然而，儘管這個龐大網路不斷將訊號從大腦傳往身體，

scientists have noted that 80 to 90% of the nerve fibers in the enteric nervous system

科學家發現，腸神經系統中80%至90%的神經纖維

are actually going from the gut to the brain.

實際上是從腸道通往大腦。

In fact, the enteric nervous system, 用詞

事實上，腸神經系統

which is an extensive mesh-like network of neurons that controls your entire digestive tract

是一張由神經元交織而成的龐大網絡，控制著你的整條消化道，

from the esophagus to the anus,

範圍從食道一路延伸到肛門，

doesn't even require the brain at all. 文法

卻根本不需要大腦。

When the vagus nerve is severed,

當迷走神經被切斷時，

the enteric nervous system is capable of organizing and initiating its own reflexes for digestion 文法

腸神經系統仍能自行組織並啟動消化反射，

because it has such a complex collection of neurons.

因為它擁有如此複雜的神經元群。

It is your second brain and controls you far more than you realize. 文法

它就是你的第二大腦，對你的控制遠超乎你的想像。

From an evolutionary perspective, 片語搭配

從演化的角度來看，

before modern food safety protocols,

在現代食品安全規範出現以前，

our biggest choices were about eating.

我們最重大的選擇都和吃有關。

Is it safe?

安全嗎？

Will it make me sick?

會讓我生病嗎？

Will it give me energy?

能給我能量嗎？

This is why we would need a direct line of communication 講解

這就是為什麼我們需要一條直接的溝通管道，

between the gut and the brain.

連接腸道與大腦。

For example, fat and sugar are good sources of fuel for the body,

例如，脂肪和糖都是身體的優質能量來源，

so we've evolved mechanisms to notify the brain

因此我們演化出了一套機制，向大腦發出訊號，

to release the feel-good neurotransmitter dopamine

促使它釋放能帶來愉悅感的神經傳導物質多巴胺。

when we eat foods high in fats and sugars, 片語搭配

這發生在我們吃下高脂肪、高糖的食物時，

which make us continually seek them out. 片語動詞

並讓我們不斷想去尋找它們。

But the enteric nervous system becomes even more interesting

但當你意識到以下這件事時，腸神經系統會變得更有意思：

when you realize that the microbes in your gut

你腸道裡的微生物

actually produce over 50% of the dopamine found in your body

其實會製造你體內超過50%的多巴胺，

and 90% of the serotonin,

以及90%的血清素——

two neurotransmitters that drastically affect your mood,

這兩種神經傳導物質會大幅影響你的情緒、

happiness, and pleasure.

幸福感和愉悅感。

And these microbes can manipulate your cravings and eating behaviors

而且，這些微生物還能操控你的食慾和進食行為，

for their own survival.

以確保自己生存。

Your diet affects which bacteria thrive,

你的飲食會影響哪些細菌能夠繁盛，

but as a result,

而結果是，

the flourishing bacteria in your gut can then send signals to the brain

你腸道中大量繁殖的細菌便能向大腦發送訊號，

via the vagus nerve to tell you to keep eating the foods that they love. 文法

透過迷走神經，要你繼續吃它們喜歡的食物。

This is why some scientists have suggested that treatment with probiotics or fecal transplants 講解

這就是為什麼有些科學家認為，利用益生菌或糞菌移植進行治療，

could be an effective therapy for overeating,

可能是改善過度進食的有效療法，

by getting rid of certain bacteria that generate intense cravings 講解

方法是清除某些會讓人強烈渴望

for high-fat and high-sugar foods.

高脂肪、高糖食物的細菌。

In fact, current research is pointing to a gut with healthy microbiomes 片語動詞

事實上，目前的研究顯示，擁有健康微生物群的腸道

as a strong predictor of emotional and mental health. 片語搭配

是預測情緒和心理健康狀況的有力指標。

Mice raised in sterile environments where no bacteria could colonize their gut 文法

在無菌環境中長大、沒有任何細菌能在其腸道內定殖的小鼠，

exhibit social traits similar to those seen in humans on the autism spectrum. 講解

會表現出類似自閉症光譜族群的社交特徵。

When researchers studied their brains,

當研究人員研究牠們的大腦時，

they also found significant changes in the levels of serotonin

也發現牠們的血清素濃度出現顯著變化，

and specific proteins related to learning and memory formation.

與學習和記憶形成有關的特定蛋白質也有明顯變化。

But after feeding the mice with specific probiotics to help cultivate healthy microbiomes,

但研究人員餵小鼠吃特定益生菌，幫助培養健康微生物群後，

the symptoms were alleviated. 用詞

這些症狀便得到緩解。

Their gut controlled their behavior.

是牠們的腸道控制了牠們的行為。

A 30-day study comparing people who ate probiotic yogurt found a decrease 文法

一項為期30天的研究比較了食用益生菌優格的人，結果發現，

in the levels of anxiety and depression compared to people who consumed milk with no bacteria.

和飲用不含細菌的牛奶的人相比，他們的焦慮與憂鬱程度都降低了。

And another study found that mice fed a specific bacteria

另一項研究發現，餵食了某種特定細菌的小鼠

had less stress-related hormones in their blood

血液中與壓力有關的荷爾蒙較少，

and performed better on tests of learning and memory.

在學習與記憶測驗中的表現也更好。

But when researchers severed the vagus nerve,

但當研究人員切斷迷走神經後，

all of these improvements disappeared.

所有這些改善都消失了。

Again, their guts were in control of their emotions. 片語搭配

再一次，是牠們的腸道在控制牠們的情緒。

Studies have even shown that stimulating the vagus nerve

研究甚至顯示，刺激迷走神經——

at different frequencies by implanting a small pacemaker 文法

透過植入小型心律調節器，以不同頻率進行刺激——

can help patients with treatment-resistant depression 用詞

能幫助患有難治型憂鬱症的病人，

by mimicking vagal nerve activity like a person with a healthy gut.

因為它能模擬腸道健康者的迷走神經活動。

And the essential role of the gut doesn't end there. 慣用語

而腸道不可或缺的作用還不只如此。

Given that large social groups increase the potential of one's genes being passed on 講解

鑑於大型社會群體能提高個體基因傳承下去的機率，

for both us and our bacteria,

對我們和體內的細菌來說都是如此，

researchers now believe that the function of the microbiome is partly to promote prosocial behaviors. 用詞

研究人員現在認為，微生物群的部分功能是促進親社會行為。

Healthy gut bacteria can lead to a higher resilience of negative emotions from others,

健康的腸道細菌能增強你抵禦他人負面情緒的能力，

which makes you more forgiving and better at fostering strong social connections, 講解

讓你更寬容，也更善於建立牢固的社交連結，

ultimately improving your shot at reproduction. 慣用語

最終提高你繁衍後代的機會。

All thanks to your second brain.

這一切都要歸功於你的第二大腦。

Special thanks to Audible for supporting this episode

特別感謝Audible贊助本集，

to give you a free 30-day trial at audible.com/asap.

讓你可以在audible.com/asap免費試用30天。

This week we wanted to recommend the book How Not to Be Wrong,

本週，我們想推薦《How Not to Be Wrong》這本書，

The Power of Mathematical Thinking,

副標題是《The Power of Mathematical Thinking》，

which helped us create our previous episode Are Good-Looking People Jerks?

它曾幫助我們製作上一集影片《Are Good-Looking People Jerks?》。

It's an awesome read.

這是一本非常精彩的書。

You can get a free 30-day trial at audible.com/asap

你可以前往audible.com/asap，獲得30天免費試用，

and choose from a massive selection. We love them as they're great when you're on the go. 慣用語

並從海量有聲書中任意挑選。我們很喜歡它們，因為出門在外時聽特別方便。

And subscribe for more weekly science videos.

別忘了訂閱，每週觀看更多科學影片。