如果你有第二个大脑会怎样？：英语精读讲义

The brain.

大脑。

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

每当你思考、感受，或进行大量无意识活动时，

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

你颅骨内的1000亿个神经元就会传导电信号，彼此沟通、传递信息，

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

最终造就了——嗯——你，以及你所做的一切。

It's the most complex,

它是人体内最复杂、

essential, and identifiable organ in the body,

最不可或缺、也最具辨识度的器官，

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

是所有脊椎动物神经系统的中枢。

But what if how you think and feel 語法

但如果你的思维和感受

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

并不只是由大脑和中枢神经系统控制，

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

而其实还受到一个你从未察觉的“第二大脑”控制呢？

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

大脑通过迷走神经与身体的许多部位相连并交流，

including the vocal cords,

包括声带、

heart, lungs, and most of the digestive tract.

心脏、肺，以及消化道的大部分区域。

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

它还通过这条神经向身体传递“战斗或逃跑”的信号，

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

这就解释了为什么你可能会声音发颤、

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. 習語

并在压力很大或非常紧张时感觉胃里揪成一团。

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

然而，尽管这个庞大的网络不断将信号从大脑传向身体，

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

科学家发现，肠神经系统中80%到90%的神经纤维

are actually going from the gut to the brain.

实际上是从肠道通往大脑的。

In fact, the enteric nervous system, 用詞

事实上，肠神经系统

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

是一张由神经元交织而成的庞大网络，控制着你的整条消化道，

from the esophagus to the anus,

范围从食管一直延伸到肛门，

doesn't even require the brain at all. 語法

却根本不需要大脑。

When the vagus nerve is severed,

当迷走神经被切断时，

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

肠神经系统仍能自行组织并启动消化反射，

because it has such a complex collection of neurons.

因为它拥有如此复杂的神经元群。

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

它就是你的第二大脑，对你的控制远超你的想象。

From an evolutionary perspective, 短語搭配

从进化的角度来看，

before modern food safety protocols,

在现代食品安全规范出现之前，

our biggest choices were about eating.

我们最重大的选择都与吃有关。

Is it safe?

它安全吗？

Will it make me sick?

会让我生病吗？

Will it give me energy?

能给我提供能量吗？

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

这就是为什么我们需要一条直接的沟通渠道，

between the gut and the brain.

连接肠道与大脑。

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

例如，脂肪和糖是身体的优质能量来源，

so we've evolved mechanisms to notify the brain

所以我们进化出了一套机制，向大脑发出信号，

to release the feel-good neurotransmitter dopamine

促使它释放能带来愉悦感的神经递质多巴胺。

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

这发生在我们吃下高脂肪、高糖的食物时，

which make us continually seek them out. 短語動詞

并让我们不断想去寻找它们。

But the enteric nervous system becomes even more interesting

但当你意识到以下这件事时，肠神经系统会变得更加有趣：

when you realize that the microbes in your gut

你肠道中的微生物

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

实际上会产生你体内超过50%的多巴胺，

and 90% of the serotonin,

以及90%的血清素——

two neurotransmitters that drastically affect your mood,

这两种神经递质会显著影响你的情绪、

happiness, and pleasure.

幸福感和愉悦感。

And these microbes can manipulate your cravings and eating behaviors

而且，这些微生物还能操纵你的食欲和进食行为，

for their own survival.

以确保自身生存。

Your diet affects which bacteria thrive,

你的饮食会影响哪些细菌能够繁盛，

but as a result,

而由此一来，

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

你肠道里大量繁殖的细菌便能向大脑发送信号，

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

通过迷走神经让你继续吃它们喜欢的食物。

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

正因如此，一些科学家提出，使用益生菌或粪菌移植进行治疗，

could be an effective therapy for overeating,

或许能成为应对过度进食的有效疗法，

by getting rid of certain bacteria that generate intense cravings 講解

具体做法是清除某些会让人强烈渴望

for high-fat and high-sugar foods.

高脂肪、高糖食物的细菌。

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

事实上，目前的研究表明，拥有健康微生物群的肠道

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

是预测情绪和心理健康状况的有力指标。

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

在无菌环境中长大、没有任何细菌能在其肠道内定植的小鼠，

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

会表现出类似于孤独症谱系人群的社交特征。

When researchers studied their brains,

当研究人员研究它们的大脑时，

they also found significant changes in the levels of serotonin

还发现它们的血清素水平发生了显著变化，

and specific proteins related to learning and memory formation.

与学习和记忆形成相关的特定蛋白质也有明显变化。

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

但研究人员给小鼠喂食特定益生菌，以帮助培养健康的微生物群后，

the symptoms were alleviated. 用詞

这些症状得到了缓解。

Their gut controlled their behavior.

是它们的肠道控制了它们的行为。

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

一项为期30天的研究比较了食用益生菌酸奶的人群，结果发现，

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

与饮用不含细菌的牛奶的人相比，他们的焦虑和抑郁程度有所下降。

And another study found that mice fed a specific bacteria

另一项研究发现，喂食了某种特定细菌的小鼠

had less stress-related hormones in their blood

血液中与压力相关的激素更少，

and performed better on tests of learning and memory.

在学习和记忆测试中的表现也更好。

But when researchers severed the vagus nerve,

但当研究人员切断迷走神经后，

all of these improvements disappeared.

所有这些改善都消失了。

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

再一次，是它们的肠道在控制它们的情绪。

Studies have even shown that stimulating the vagus nerve

研究甚至表明，刺激迷走神经——

at different frequencies by implanting a small pacemaker 語法

通过植入小型起搏器，以不同频率进行刺激——

can help patients with treatment-resistant depression 用詞

能够帮助患有难治性抑郁症的患者，

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

因为它能模拟肠道健康者的迷走神经活动。

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

而肠道不可或缺的作用还不止于此。

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

鉴于庞大的社会群体能提高个体基因传递下去的概率，

for both us and our bacteria,

这对我们和体内的细菌都一样，

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

研究人员如今认为，微生物群的部分功能是促进亲社会行为。

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

健康的肠道细菌可以增强你抵御他人负面情绪的能力，

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

让你更宽容，也更善于建立牢固的社会联系，

ultimately improving your shot at reproduction. 習語

最终提高你繁衍后代的机会。

All thanks to your second brain.

这一切都要归功于你的第二大脑。

Special thanks to Audible for supporting this episode

特别感谢Audible对本期节目的支持，

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

让你可以在audible.com/asap免费试用30天。

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

本周，我们想推荐《How Not to Be Wrong》这本书，

The Power of Mathematical Thinking,

副标题是《The Power of Mathematical Thinking》，

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

它曾帮助我们制作上一期视频《Are Good-Looking People Jerks?》。

It's an awesome read.

这是一本非常精彩的书。

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

你可以前往audible.com/asap，获得30天免费试用，

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

并从海量有声书中任意挑选。我们很喜欢它们，因为出门在外时听特别方便。

And subscribe for more weekly science videos.

别忘了订阅，每周观看更多科学视频。