基础要点：味觉感知与糖分渴望的生物学 | Charles Zuker博士

欢迎来到胡伯曼实验室精华版，在这里我们会回顾过往的节目，为您带来最有效且可操作的、基于科学的心理健康、身体健康和表现提升工具。

Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science based tools for mental health, physical health, and performance.

我是安德鲁·胡伯曼，斯坦福大学医学院神经生物学和眼科学教授。

I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine.

接下来，让我与查尔斯博士展开对话。

And now for my discussion with Doctor.

查尔斯·祖克。

Charles Zuker.

查尔斯，非常感谢你今天加入我。

Charles, thank you so much for joining me today.

我的荣幸。

My pleasure.

我想

I want to

向你请教许多关于味觉和味觉感知的问题，但也许我们可以先从一个更基础的问题开始：因为你曾在神经科学的多个领域开展研究，而不仅仅是味觉，那么世界和人们应该如何理解感知？它与感觉有何不同？是什么造就了我们对视觉、听觉、味觉等生命体验的感知？

ask you about many things related to taste and gustatory perception, but maybe to start off, and because you've worked on a number of different topics in neuroscience, not just taste, how should the world and people think about perception, how it's different from sensation, and what leads to our experience of life in terms of vision, hearing, taste, etcetera.

世界是由真实的事物构成的。

The world is made of real things.

这个是玻璃杯，这个是电线，这个是麦克风。

This here is a glass, and this is a cord, and this is a microphone.

但大脑只由神经元组成，而神经元只理解电信号。

But the brain is only made of neurons that only understand electrical signals.

那么，你如何将这种现实转化为仅仅是代表世界的电信号？这一过程就是我们可以操作性定义为知觉的东西。

So how do you transform that reality into nothing but electrical signals that now need to represent the world, and that process is what we can operationally define as perception.

在感官中，比如嗅觉、气味、味觉、视觉，我们可以非常直接地将检测与知觉区分开来。

In the senses, let's say olfactory, odor, taste, vision, we can very straightforwardly separate detection from perception.

检测发生在你取一个糖分子，把它放在舌头上，然后一组特定的细胞感知到这个糖分子时。

Detection is what happens when you take a sugar molecule, you put it in your tongue, and then a set of specific cells now sense that sugar molecule.

这就是检测。

That's detection.

你还没有产生任何知觉。

You haven't perceived anything yet.

这仅仅是你们舌头上的细胞与这种化学物质相互作用的结果。

That is just yourselves in your tongue interacting with this chemical.

但当这个细胞被激活并向大脑发送信号时，检测就转化为了知觉。他正试图理解这一过程是如何发生的，这正是我整个神经科学事业的执着追求。

But now that cell gets activated and sends a signal to the brain, and now detection gets transformed into perception, And he's trying to understand how that happens, that's been the maniacal drive of my entire career in neuroscience.

大脑最终是如何将检测转化为知觉，从而指导行为和行动的呢？

How does the brain ultimately transform detection into perception so that it can guide actions and behaviors?

因此，如果我想开始探索大脑所做的一切，我觉得必须选择一个感官系统，它的输入输出关系具有某种程度的简洁性，同时又能用来探讨大脑必须最终计算、编码和解码的所有这些问题。

So, if I want to begin to explore all of these things that the brain does, I felt I have to choose a sensory system that affords some degree of simplicity in the way that the input output relationships are put together, and in a way that still can be used to ask every one of these problems that the brain has to ultimately compute, encode, and decode.

在我刚开始研究这个领域时，味觉系统最引人注目的是，当时人们对味觉的分子基础一无所知。

And what was remarkable about the taste system at the time that I began working on this, is that nothing was known about the molecular basis of taste.

我们知道，我们能够分辨通常定义的五种基本味觉：甜、酸、苦、咸和鲜味。

You know, we knew that we could taste what has been usually defined as the five basic taste qualities: sweet, sour, bitter, salty, and umami.

鲜味是日语词汇，意思是美味、可口，而几乎所有动物物种对氨基酸的感知就是这种味道。

Umami is a Japanese word that means yummy, delicious, and that's, nearly every animal species, the taste of amino acids.

在人类中，它主要与味精（谷氨酸钠）的味道相关，特别是其中一种氨基酸。

And in humans, it's mostly associated with the taste of MSG, monosodium glutamate, one amino acid in particular.

因此，这个系统的美妙之处在于，输入通道仅有五种，每一种都有预设的含义。

And so, the beautiful thing of the system is that the lines of input are limited to five, and each of them has a predetermined meaning.

你生来就对甜味、鲜味和低盐味具有特定的偏好价值。

You're born with that specific valence value for each taste of sweet, umami, and low salt are attractive taste qualities.

它们会引发摄食反应，我想要摄入它们。

They evoke appetitive responses, I want to consume them.

而苦味和酸味则天生被预设为令人厌恶的。

And bitter and sour are innately predetermined to be aversive.

以苦味为例，我们很容易观察到动物身上的反应：首先你会停止舔舐，然后露出不悦的表情，接着眯起眼睛，最后开始干呕，明白吗？

In the case of bitter, it's very easy to actually look at, see them happening in animals, because the first thing you do is you stop licking, then you put unhappy face, then you squint your eyes, and then you start gagging, okay?

这一切都是由舌头上的苦味感受细胞被苦味分子激活所引发的。

And that entire thing happens by the activation of a bitter molecule in a bitter sensing cell in your tongue.

这太不可思议了。

It's incredible.

这再次体现了大脑的神奇之处——它竟能仅凭简单而独特的感官刺激，编码和解码出如此复杂的行为反应。

It's, again, the magic of the brain, you know, how it's able to encode and decode these extraordinary actions and behaviors in response of nothing but a simple, very unique sensory stimuli.

这五种基本味觉满足了生物体的所有饮食需求。

This palette of five basic tastes accommodates all the dietary needs of the organism.

甜味确保我们摄入足够的能量，鲜味确保我们获得蛋白质——另一种必需营养素，盐味（这三种重复的味觉）确保我们维持电解质平衡，苦味防止摄入有毒或令人作呕的化学物质，几乎所有野生的苦味物质都对身体有害，而酸味则很可能用于防止摄入变质的酸性或发酵食品。

Sweet to ensure that we get the right amount of energy, umami to ensure that we get proteins, another essential nutrient, salt, the three repetitive ones, to ensure that we maintain our electrolyte balance, bitter to prevent the ingestion of toxic, nauseous chemicals, nearly all bitter tasting, you know, things out in the wild are bad for you, and sour, most likely to prevent the ingestion of spoiled acid, fermented foods.

就是这样。

And that's it.

这就是我们所面对的味觉体系。

That is the palate that we deal with.

当然，基本味觉和风味之间是有区别的。

Now, of course, there's a difference between basic taste and flavor.

风味是整个体验。

Flavor is the whole experience.

风味是多种味觉的结合，再加上气味、质地、温度和外观，共同构成了你我所说的完整感官体验。

Flavor is the combination of multiple tastes coming together, together with smell, with texture, with temperature, with the look of it, that gives you what you and I would call the full sensory experience.

但作为科学家，我们需要将这个问题简化为基本要素，以便先拆解它，然后再重新组合。

But we scientists need to reduce the problem into its basic elements so we can begin to break it apart before we put it back together.

当我们思考味觉时，试图弄清楚这些信息如何从舌头传递到大脑，如何被信号化、整合，并触发各种不同行为时，我们会将它们视为独立的品质。

So, when we think about the sense of taste, and we try to figure out how these lines of information go from your tongue to your brain, and how they signal, and how they get integrated, and how they trigger all these different behaviors, we look at them as individual qualities.

因此，我们会给动物甜味，或苦味，或酸味。

So, we give the animal sweet, or we give them a bitter, we give them sour.

我们避免混合。

We avoid mixes.

可以把它们想象成信息的独立通道，就像钢琴的琴键一样。

Think of it as lines of information, just separate lines, like the keys of a piano.

甜、酸、苦、咸、鲜，你按下其中一个键，就激活了那一个和弦。

Sweet, sour, beat, salty, mame, you play the key and you activate that one chord.

而这个和弦，在钢琴中会产生一个音符，也就是一段旋律；在味觉中，则会引发一种行为和反应。

And that one chord, in the case of a piano, leads to a note, you know, a tune, and in the case of taste, leads to an action and a behavior.

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They're giving away a free bottle of vitamin D3K2, a bottle of omega-three fish oil capsules, and a sample pack of the new sleep formula AGZ, which by the way is now the only sleep supplement I take.

效果太棒了，我服用 AGZ 后的睡眠质量好得不可思议。

It's fantastic, my sleep on AGZ is out of this world good.

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AGZ is a drink, so it eliminates the need to take a lot of pills.

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It tastes great.

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And like I said, it has me sleeping incredibly well, waking up more refreshed than ever.

我非常喜欢它。

I absolutely love it.

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如果你要描述导致味觉感知事件的一系列神经事件。

If you would describe the sequence of neural events leading to a perceptual event of taste.

我们的舌头上分布着味蕾。

We have taste buds distributed in various parts of the tongue.

味蕾的分布确实存在某种图谱，但每个味蕾大约包含100个味觉受体细胞，这些细胞可分为五种类型：甜、酸、苦、咸或鲜味。

So there is a map on the distribution of taste buds, but each taste bud has around a 100 taste receptor cells, and those taste receptor cells can be of five types, sweet, sour, bitter, salty, or umami.

在大多数情况下，所有味蕾都具备这五种味觉品质的代表。

And for the most part, all taste buds have the representation of all five taste qualities.

毫无疑问，某些味道确实存在轻微的分布偏好，比如苦味在舌根区域特别集中，这背后有其目的性，实际上也有生物学依据。

Now, there's no question that there is a slight bias for some tastes, like bitter is particularly enriched at the very back of your tongue, and there is a teleological basis for that, actually a biological basis for that.

这是在吞咽有害物质前的最后一道防线。

That's the last line of defense before you swallow something bad.

因此，确保舌根区域拥有大量这类不良物质受体至关重要，一旦被激活，就能触发呕吐反射，将可能致命的物质排出体外。

And so, let's make sure that the very back of your tongue has plenty of these bad noose receptors so that if they get activated you can trigger a gagging reflex and get rid of this that otherwise may kill you.

重要的是，这五种味觉的受体——也就是感知甜、酸、苦、咸、鲜的分子探测器——是位于味觉受体细胞表面的蛋白质，它们与这些化学物质相互作用；一旦结合，就会在细胞内引发一系列生化反应，最终产生电信号，向大脑传递‘这里有甜味’或‘这里有咸味’的信息。

The important thing is that, you know, after the receptors for these five, the detectors, the molecules that sends sweet, sour, beetle, saltsumami, these are receptors, proteins found on the surface of taste receptor cells that interact with these chemicals, and once they interact, then they trigger the cascade of events, biochemical events inside the cell that now sends an electrical signal that says, There is sweet here, or There is salt here.

让我们比较一下甜味和苦味，追踪它们从舌头到大脑的路径。

Let's compare and contrast sweet and bitter, as we follow their lines from the tongue to the brain.

首先，这两种味道引发的是截然相反的行为。

So, the first thing is that the two evoke diametrically opposed behaviors.

如果我们必须选出两种代表极端对立的感官体验，那一定是甜味和苦味。

If we have to come up with two sensory experiences that represent polar opposites, it will be sweet and bitter.

因此，如果我们追踪这两条信号通路，它们就像键盘两端的两个独立按键，按下其中一个键，就会激活这一通路：你口腔中的所有甜味细胞都会汇聚到下一个站点的一组甜味神经元中，这个站点仍在大脑之外，属于味觉神经节。

So then the signals, if we follow now these two lines, they're really like two separate keys at the two ends of this keyboard, and you press one key and you activate this cord, so you activate the sweet cells throughout your oral cavity, and they all converge into a group of sweet neurons in the next station, which is still outside the brain, is one of the taste ganglia.

这些神经元支配着你的舌头和口腔。

These are the neurons that innervate your tongue and the oral cavity.

它们大致位于哪里？

Where do they sit approximately?

就在这里，是的。

There, yeah.

对，就在淋巴结附近，差不多。

Yeah, right here around the lymph nodes, more or less.

明白了。

You got it.

有两个主要的神经节支配口腔内绝大多数味蕾。

And there are two main ganglia that innervate the vast majority of all taste buds in the oral cavity.

从那里，甜味信号传送到脑干。

And then from there, that sweet signal goes onto the brainstem.

脑干是身体进入大脑的入口，脑干中有不同的区域，也有不同的神经元群，而在脑干吻侧的一个独特、拓扑定位明确的区域，接收所有的味觉输入。

The brain stem is the entry of the body into the brain, and there are different areas of the brain stem, and there are different groups of neurons in the brain stem, and there's a unique area, in a unique topographically defined location in the rostral side of the brainstem that receives all of the taste input.

大脑中一个非常密集的区域。

A very dense area of the brain.

大脑中一个非常丰富的区域，没错。

A very rich area of the brain, exactly.

从那里，甜味信号继续传送到脑干更高处的另一个区域，然后经过多个中继站，甜味信号从一个甜味神经元传递到另一个甜味神经元，最终到达你的皮层。

And from there, the sweet signal goes to this other area higher up on the brain stem, and then it goes through a number of stations where that sweet signal goes from sweet neuron to sweet neuron to sweet neuron to eventually get to your cortex.

一旦信号到达你的味觉皮层，意义就被赋予到这个信号中。

And once it gets to your taste cortex, that's where meaning is imposed into that signal.

根据数据，现在你可以将这种刺激识别为甜味刺激。

It's then, this is what the data suggests, that now you can identify this as a sweet stimuli.

这一切发生得有多快？

And how quickly does that all happen?

你知道，神经系统的反应时间很快，对吧？

You know, the timescale of the nervous system, it's fast, yeah?

不到一秒钟。

Within less than a second.

是的，事实上我们可以通过在每个这些节点上插入电极来证明这一点：当你施加刺激后，几毫秒内就能在后续节点上观察到反应。

Yeah, and in fact, we can demonstrate this because we can stick electrodes at each of these stations, you deliver the stimuli, and within a fraction of a second, you see now the response in these following stations.

当信号到达皮层时，你便为这种味觉赋予了意义。

Now it gets to the cortex, and now in there you impose meaning to that taste.

你的大脑中有一个区域代表甜味的味觉，另一个不同的区域则代表苦味的味觉。

There's an area of your brain that represents the taste of sweet in taste cortex and a different area that represents the taste of bitter.

本质上，你的大脑内部存在一个味觉品质的拓扑图谱。

In essence, there is a topographic map of these taste qualities inside your brain.

你认为这种可塑性有多大，尤其是在人的一生中？

How much plasticity do you think there is there, and in particular across the lifespan?

因为我认为最明显的例子之一是，孩子似乎不喜欢某些蔬菜，但他们天生就喜欢甜味。

Because I think one of the most salient examples of this is that kids don't seem to like certain vegetables, but they all are hardwired to like sweet tastes.

然而，你也可以想象，他们最终会接受蔬菜的原因之一，是因为他们知道蔬菜可能对身体有益——

And yet you could also imagine that one of the reasons why they may eventually grow to incorporate vegetables is because of some knowledge that vegetables might be-

对你有好处。

Good for you.

对他们更好。

Better for them.

在从童年早期抗拒蔬菜到愿意吃蔬菜的转变过程中，是否存在受体的变化可以解释这一现象？

Is there a change in the receptors that can explain the transition from wanting to avoid vegetables to being willing to eat vegetables, simply in childhood to early development.

味觉，我们刚刚说过，是预先设定且天生固定的。

So, taste, we just told you that's, you know, predetermined hardwired.

但预先设定和天生固定并不意味着它不会被学习或经验所调节，它只意味着你生来就喜欢甜味、讨厌苦味。

But predetermined hardwired doesn't mean that it's not modulated by learning or experience, it only means that you are born like in sweet and dislike in bitter.

我们有很多可塑性的例子。

And we have many examples of plasticity.

咖啡对系统有正向收益，这种从负面信号中产生的正向价值足以建立这种积极关联。

Coffee, it has an associated gain to the system, and that gain to the system, that positive valence that emerges out of that negative signal is sufficient to create that positive association.

就咖啡而言，当然是咖啡因激活了一整套神经递质系统，让你感受到与咖啡相关的愉悦感。

I mean, the case of coffee, of course, it's caffeine activating a whole group of neurotransmitter systems that give you that high associated with coffee.

所以，是的，这个味觉系统是可变的、可塑的，并且会受到学习和经验的影响。

So yes, this taste system is changeable, it's malleable, and is subjected to learning and experience.

你能想象出一种人们可以利用这种机制的系统吗？

Can you imagine a sort of a system by which people could leverage that?

这种脱敏现象发生在哪儿？

Where does this desensitizing happens?

这是我们使用的术语，我认为它发生在多个层面。

That's the term that we use, I think happening at multiple stations.

它发生在受体层面，我。

It's happening at the receptor level, I.

嗯，你舌头上来感知糖分的细胞。

E, the cells in your tongue that are sensing that sugar.

当你持续激活这个受体，它不断触发活动，最终你会让受体疲劳。

As you activate this receptor and it's triggering activity after activity after activity, eventually you exhaust the receptor.

再次说明，我用的这些术语非常宽松。

Again, I'm using terms which are extraordinarily loose.

受体会达到一个状态，发生一系列化学变化，使其信号传递效率大幅降低，甚至被从细胞表面移除，这是这种调节机制的重要部分。

The receptor gets to a point where it undergoes a set of changes, chemical changes, where it now signals far less efficiently, or it even gets removed from the surface of the cell, and that is a huge side of this modulation.

接下来，我认为是整合性的信号减弱，这种减弱发生在整个神经通路的各个节点上，从舌头到神经节，从神经节到脑干的第一个节点，再到脑干的第二个节点，然后到丘脑，最后到皮层。

And then the next, I believe, is the integrated, again, loss of signaling that happens by continuous activation of the circuit at each of these different neural stations, from the tongue to the ganglia, from the ganglia to the first station in the brainstem, a second station in the brainstem to the thalamus, then to the cortex.

因此，这个信号要经过多个步骤传递。

So there are multiple steps that this signal is traveling.

你可能会问，既然这是条标签通路，为什么需要这么多节点？

Now, you might say, Why, if this is a label line, why do you need to have so many stations?

这是因为味觉系统至关重要，必须确保你获得生存所需的东西，因此它必须受到内部状态的调节，而每个节点都提供了新的可塑性和调节位点。

And that's because the taste system is so important to ensure that you get what you need to survive, that it has to be subjected to modulation by the internal state, and each of these nodes provides a new site to give it plasticity and modulation.

我来给你举一个例子，说明内部状态如何改变味觉系统的工作方式。

I'm going to give you one example of how the internal state changes the way the taste system works.

低浓度的盐非常诱人，因为我们需要它。

Salt is very appetitive at low concentrations, and that's because we need it.

我们的电解质平衡需要盐，每一个神经元都依赖盐作为最重要的离子之一，配合钾离子，以确保在神经元内部和神经元之间传递电信号。

Our electrolyte balance requires salt, every one of their neurons uses salt as the most important of the ions, you know, with potassium to ensure that you can transfer these electrical signals within and between neurons.

但在高浓度下，比如海水，它会变得极其令人反感，我们都明白这一点，因为当你去海边，海水进到嘴里时，感觉并不好。

But at high concentrations, let's say ocean water, it's incredibly aversive, and we all know this because we've gone to the ocean and then when you get it in your mouth, it's not that great.

然而，如果我让你长期缺盐，那么这种极高浓度的盐——一摩尔的氯化钠——会变得异常诱人和吸引人。

However, if I salt deprive you, now this incredibly high concentration of salt, one molar sodium chloride, becomes amazingly appetitive and attractive.

这里到底发生了什么？

What's going on in here?

你的舌头告诉你这很糟糕，但你的大脑却告诉你你需要它。

Your tongue is telling you this is horrible, but your brain is telling you you need it.

这就是我们所说的内部状态对味觉系统的调节。

And this is what we call the modulation of the taste system by the internal state.

我想稍作休息，感谢我们的赞助商LMNT。

I'd like to take a quick break and acknowledge one of our sponsors, LMNT.

LMNT是一种电解质饮料，含有你所需的一切，而没有任何不需要的成分。

LMNT is an electrolyte drink that has everything you need and nothing you don't.

也就是说，含有适量的电解质——钠、镁和钾，但不含糖。

That means the electrolytes, sodium, magnesium, and potassium in the correct amounts, but no sugar.

适当的水分补充对大脑和身体的最佳功能至关重要。

Proper hydration is critical for optimal brain and body function.

即使轻微的脱水也会降低认知和体能表现。

Even a slight degree of dehydration can diminish cognitive and physical performance.

同时，确保摄入足够的电解质也很重要。

It's also important that you get adequate electrolytes.

电解质——钠、镁和钾——对您体内所有细胞的功能至关重要，尤其是神经元或神经细胞。

The electrolytes, sodium, magnesium, and potassium, are vital for functioning of all the cells in your body, especially your neurons or your nerve cells.

饮用溶解在水中的电解质，能让你轻松确保获得充足的水分和电解质。

Drinking element dissolved in water makes it very easy to ensure that you're getting adequate hydration and adequate electrolytes.

为了确保我摄入足够的水分和电解质，我每天早上一醒来就会将一包Element溶解在约480到950毫升的水中，并且第一时间喝掉。

To make sure that I'm getting proper amounts of hydration and electrolytes, I dissolve one packet of element in about 16 to 32 ounces of water when I first wake up in the morning, and I drink that basically first thing in the morning.

在进行任何体力活动时，我也会饮用溶解了Element的水，尤其是在炎热的天气里，大量出汗导致水分和电解质流失的时候。

I'll also drink Element dissolved in water during any kind of physical exercise that I'm doing, especially on hot days when I'm sweating a lot and losing water and electrolytes.

Element有多种非常好喝的口味。

Element has a bunch of great tasting flavors.

我特别喜欢覆盆子味和柑橘味。

I love the raspberry, I love the citrus flavor.

目前，LMNT推出了一款限量版的柠檬水口味，简直美味至极。

Right now, LMNT has a limited edition lemonade flavor that is absolutely delicious.

我不太愿意说哪一个口味是我最爱的，但这款柠檬水口味绝对和我其他的最爱——覆盆子或西瓜味——不相上下。

I hate to say that I love one more than all the others, but this lemonade flavor is right up there with my other one, which is raspberry or watermelon.

再说一遍，我实在无法只选一种口味。

Again, I can't pick just one flavor.

我全都喜欢。

I love them all.

如果你想尝试LMNT，可以访问drinkelement.com/huberman或spelleddrinklmnt.com/huberman，购买任何Element饮品粉时即可免费领取一份Element试用装。

If you'd like to try LMNT, you can go to drinkelement.com/huberman, spelleddrinklmnt.com/huberman to claim a free Element sample pack with a purchase of any Element drink mix.

再次提醒，访问drinkelement.com/huberman即可领取免费试用装。

Again, that's drinkelement.com/huberman to claim a free sample pack.

我非常希望你能谈谈肠道与大脑之间的信号传递，这些信号如何在我们完全无意识的情况下驱动或改变我们的感知和行为。

I'd love you to talk about the aspects of gut brain signaling that drive or change our perceptions and behaviors that are completely beneath our awareness.

是的。

Yes.

你知道，大脑需要持续监测我们每一个器官的状态。

You know, the brain needs to monitor the state of every one of our organs.

它必须这么做。

It has to do it.

这是大脑确保所有器官协同工作、维持我们生理健康状态的唯一方式。

This is the only way that the brain can ensure that every one of those organs are working together in a way that we have healthy physiology.

这是一个双向通道，大脑不仅在监测，还在回传调节信号，告诉身体该做什么，这包括从监测心跳频率、呼吸周期中的吸气与呼气，到你摄入糖分和脂肪后身体的反应。

This is a two way highway, where the brain is not only monitoring, but is now modulating back what the body needs to do, and that includes all the way from monitoring the frequency of heartbeats and the way that inspiration and aspirations in the breathing cycle operate, to what happens when you ingest sugar and fat.

让我给你举个例子。

Let me give you an example.

巴甫洛夫在他的经典条件反射实验中，每次给狗喂食前都会摇铃。

So, Pavlov, in his classical experiments in conditioning, you know, associative conditioning, he would take a bell, it would ring the bell every time he was going to feed the dog.

最终，狗学会了将铃声与食物的到来联系起来。

Eventually, the dog learned to associate the ringing of the bell with food coming.

现在，即使只听到铃声，狗也会开始流口水，从神经学角度来说，这被称为预期反应。

The dog now, in the presence of the bell alone, will start to salivate, and we will call that, you know, neurologically speaking, an anticipatory response.

大脑中形成这种关联的神经元现在代表食物即将到来，并向运动神经元发送信号，促使唾液腺收缩，从而释放唾液，因为你预感到食物就要来了。

Neurons in the brain that form that association now represent food is coming and they're sending a signal to motor neurons to go into your salivary glands to squeeze them, so you release, you know, saliva because you know food is coming.

但更令人惊讶的是，这些动物在听到铃声时也会释放胰岛素。

But what's even more remarkable is that those animals are also releasing insulin in response to a bell.

某种程度上，大脑建立了这些关联，现在你的大脑中有一些神经元，即使没有食物到来，也会向胰腺发送信号，促使它释放胰岛素，因为糖分即将到达。

Somehow the brain created these associations and there are neurons in your brain now that no food is coming, and send a signal somehow all the way down to your pancreas, that now it says release insulin because sugar is coming down.

连接身体状态与大脑的主要通路是一组特定的神经，它们起源于迷走神经节和结状神经节，也就是迷走神经，它支配着你体内大多数器官，监测它们的功能，向大脑发送信号，然后大脑再反馈回来，告诉身体：‘一切正常，这么做’，或者‘情况不好，那样做’。

Now, the main highway that is communicating the state of the body with the brain is a specific bundle of nerves which emerge from the vagal ganglia, the nodos ganglia, and so it's the vagus nerve that is innervating the majority of the organs in your body, it's monitoring their function, sending a signal to the brain, and now the brain going back down and saying, this is going all right, do this, or this is not going so well, do that.

我应该指出，正如你所知，每个器官，比如脾脏、胰腺，

And I should point out, as you well know, every organ, spleen, pancreas,

它们都会被监控。

They all be monitored.

我毫不怀疑，我们通常归因于新陈代谢、生理功能甚至免疫系统的疾病，很可能实际上是大脑的疾病、状态或功能异常。

I have no doubt that diseases that we have normally associated with metabolism, physiology, and even immunity are likely to emerge as diseases, conditions, states of the brain.

我不认为肥胖是一种新陈代谢疾病。

I don't think obesity is a disease of metabolism.

我相信肥胖是一种大脑回路的疾病。

I believe obesity is a disease of brain circuits.

我也这么认为。

I do as well.

是的，长期以来，由于我们研究的分子存在于体内而非大脑中，因此我们自然将这些问题视为新陈代谢、生理学等方面的问题。

Yeah, and so this view that we have, you know, been working on for the longest time, because, you know, the molecules that we're dealing with are in the body, not in the head, you know, led us to view, of course, these issues and problems as being one of metabolism, physiology, and so forth.

这些分子仍然是最终信号的载体，但大脑显然才是协调这一系列生理和代谢活动的指挥者。

They remain to be the carriers of the ultimate signal, but the brain ultimately appears to be the conductor of this orchestra of physiology and metabolism.

现在，让我们来看看肠道大脑和糖。

Now, let's go to the gut brain and sugar.

迷走神经由数千根纤维组成，形成一个巨大的神经束，而在我们说话的时候，这些纤维中的每一根都传递着与其特定功能相关的信息。

The vagus nerve is made out of many thousands of fibers that make this gigantic bundle, and it's likely, as we're speaking, that each of these fibers, they carry meaning that's associated with their specific task.

这一组纤维正在向大脑传递你心脏的状态信息。

This group of fibers is telling the brain about the state of your heart.

这一组纤维正在向大脑传递你肠道的状态信息。

This group of fiber is telling the brain about the state of your gut.

这组纤维正在向大脑传递你的营养状态。

This is telling your brain about its nutritional state.

同样，为了做一个简单的类比，它们就像是这架钢琴的琴键。

They are, again, to make the same simple example, the keys of this piano.

这之所以重要，是因为肠道-大脑轴的奇妙之处在于，这些成千上万的纤维实际上在执行着不同的功能。

Now, the reason this is relevant, because the magic of this gut brain axis is the fact that you have these thousands of fibers really doing different functions.

好吧，让我跟你们讲讲肠道-大脑轴以及我们对糖的无尽渴望。

Okay, let me tell you about the gut brain axis and our insatiable appetite for sugar.

这是我的实验室所做的研究，早在我们发现甜味受体时就开始了。

This is work of my own laboratory, you know, that began long ago when we discovered the sweet receptors.

现在，你可以培育出缺乏这些受体的小鼠。

You can now engineer mice that lack these receptors.

因此，这些动物将无法尝出甜味。

So in essence, these animals will be unable to taste sweet.

如果你给一只正常的小鼠一瓶含有甜味物质的水，我们会放糖或人工甜味剂，明白吗？

And if you give a normal mouse a bottle containing sweet, and we're going to put either sugar or an artificial sweetener, Alright?

它们都是甜的。

They both are sweet.

它们的味道略有不同，但这只是因为人工甜味剂带有一些异味。

They have slightly different tastes, but that's simply because artificial sweeteners have some off tastes.

但从甜味受体的角度来看，它们都会激活相同的受体，触发相同的信号。

But as far as the sweet receptor is concerned, they both activate the same receptor, trigger the same signal.

如果你给动物一个选择：一瓶含糖或甜味剂的水，或者一瓶水，这只动物会以10比1的比例饮用含甜味物质的水。

And if you give an animal an option of a bottle containing sugar or a sweetener versus water, this animal will drink 10 to one from the bottle containing sweet.

这就是味觉系统。

That's the taste system.

动物会去品尝每一个，尝几口，然后说：不，我就要这个，因为它重复出现，而且我喜欢它。

The animal goes, samples each one, leaks a couple of leaks, and then says, Uh-uh, that's the one I want, because it's repetitive and because I love it.

现在，我们要把这些小鼠进行基因改造，移除它们的甜味受体。

Now, we're going to take the mice and we're going to genetically engineer it to remove the sweet receptors.

这些小鼠口腔内不再有任何能感知甜味的传感器，无论是糖分子、人工甜味剂，还是其他任何甜味物质。

So, these mice no longer have in their oral cavity any sensors that can detect sweetness, be that sugar molecule, be it an artificial sweetener, be it anything else that tastes sweet.

如果你给这些小鼠在甜味和水之间做选择，它们会同等程度地饮用两者，因为它们无法区分，它们没有甜味受体，所以甜味瓶尝起来就像水一样。

And if you give these mice an option between sweet versus water, it will drink equally well from both because it cannot tell them apart, because it doesn't have the receptor for sweet, so that sweet bottle tastes just like water.

但如果我把这只小鼠留在笼子里接下来48小时，当我48小时后回来时，这只小鼠几乎只从糖水瓶中饮水。

But if I keep the mouse in that cage for the next forty eight hours, something extraordinary happens when I come forty eight hours later, that mouse is drinking almost exclusively from the sugar bottle.

在这48小时里，小鼠学会了：这个瓶子里的东西让我感觉良好，这就是我想喝的。

During those forty eight hours, the mouse learn that there is something in that bottle that makes me feel good, and that is the bottle I want to consume.

这正是我们对糖类无法满足的渴望和渴求的根本基础，由肠脑轴调控。

And that is the fundamental basis of our unquenchable desire and our craving for sugar, and is mediated by the gut brain axis.

因此，我们推断，如果这是真的，是肠脑轴驱动了对糖的偏好，那么大脑中应该有一组神经元会对摄入后的糖产生反应。

So, we reason, if this is true, and it's the gut brain axis that's driving sugar preference, then there should be a group of neurons in the brain that are responding to post ingestive sugar.

果然，我们发现了一组大脑中的神经元正是如此，这些神经元直接从肠脑轴接收输入。

And lo and behold, we identify a group of neurons in the brain that does this, and these neurons receive their input directly from the gut brain axis.

因此，实际情况是，糖被舌头正常识别，引发一种重复性的反应。

And so, what's happening is that sugar is recognized normally by the tongue, activates an repetitive response.

当你摄入糖后，它会激活肠道中一组特定的细胞，这些细胞通过迷走神经节向大脑发送信号：我得到了我需要的东西。

Now you ingest it, and now it activates a selective group of cells in your intestines that now send a signal to the brain via the vagal ganglia that says, I got what I need.

舌头并不知道你是否得到了所需，它只知道你尝到了味道。

The tongue doesn't know that you got what you need, it only knows that you tasted it.

而这一组细胞知道糖已经到达了将被利用的部位——肠道。

This knows that it got to the point that it's going to be used, which is the gut.

于是它发送信号，强化对这种物质的摄取，因为这就是我需要的——糖，能量的来源。

And now it sends the signal to now reinforce the consumption of this thing, because this is the one that I needed, sugar, source of energy.

因此，是肠道细胞识别糖分子，并发送信号，而这一信号被迷走神经元直接接收。

So, are gut cells that recognize the sugar molecules, send a signal, and that signal is received by the vagal neuron directly.

明白了。

Got it.

这通过肠脑轴向迷走神经节中的这些神经元胞体发送信号，再传递至脑干，从而触发对糖的偏好。

And this sends a signal through the gut brain axis to the cell bodies of these neurons in the vagal ganglia, and from there to the brain stem to now trigger the preference for sugar.

你看，你希望大脑知道你成功摄入并分解了所吃的东西，转化为生命的基本构建块，比如葡萄糖、氨基酸、脂肪，因此你希望确保一旦这些物质被肠道吸收，就能收到反馈信号：这就是我需要的，明白吗？

You see, you want the brain to know that you had successful ingestion and breakdown of whatever you consume into the building blocks of life, and you know, glucose, amino acids, fat, and so you want to make sure that once they are in the form that intestines can now absorb them, is where you get the signal back saying, this is what I want, okay?

我想短暂休息一下，感谢我们的赞助商Function。

I'd like to take a quick break and acknowledge one of our sponsors, Function.

去年，我在寻找最全面的实验室检测方案后，成为了Function的会员。

Last year, I became a Function member after searching for the most comprehensive approach to lab testing.

Function提供超过100项先进的实验室检测，能全面反映你的整体健康状况。

Function provides over 100 advanced lab tests that give you a key snapshot of your entire bodily health.

这份健康快照能为你提供关于心脏健康、激素水平、免疫功能、营养状况等多方面的洞察。

This snapshot offers you with insights on your heart health, hormone health, immune functioning, nutrient levels, and much more.

Function不仅提供超过100项关乎你身心健康的生物标志物检测，还会分析这些结果，并由相关领域的顶尖医生提供专业解读。

Function not only provides testing of over a 100 biomarkers key to your physical and mental health, but it also analyzes these results and provides insights from top doctors who are expert in the relevant areas.

例如，在我使用Function做的第一次检测中，我发现自己血液中的汞含量偏高。

For example, in one of my first tests with Function, I learned that I had elevated levels of mercury in my blood.

Function不仅帮助我发现了这个问题，还提供了降低汞水平的最佳建议，包括减少金枪鱼的摄入。

Function not only helped me detect that, but offered insights into how best to reduce my mercury levels, which included limiting my tuna consumption.

我之前吃了大量金枪鱼，同时努力多吃绿叶蔬菜，并补充NAC和乙酰半胱氨酸，这两种物质都有助于谷胱甘肽的生成和解毒。

I'd been eating a lot of tuna while also making an effort to eat more leafy greens and supplementing with NAC and acetylcysteine, both of which can support glutathione production and detoxification.

我应该补充一下，通过第二次使用Function检测，我发现这种方法是有效的。

And I should say by taking a second function test, that approach worked.

全面的血液检测至关重要。

Comprehensive blood testing is vitally important.

有许多与你的身心健康相关的问题，只有通过血液检测才能发现。

There's so many things related to your mental and physical health that can only be detected in a blood test.

问题是，血液检测一直非常昂贵且复杂。

The problem is blood testing has always been very expensive and complicated.

相比之下，我对Function的简洁性以及其低廉的价格印象深刻。

In contrast, I've been super impressed by Function simplicity and at the level of cost, it is very affordable.

因此，我决定加入他们的科学顾问委员会，并且非常高兴他们赞助了这个播客。

As a consequence, I decided to join their scientific advisory board and I'm thrilled that they're sponsoring the podcast.

如果你想尝试 Function，可以访问 functionhealth.com/huberman。

If you'd like to try Function, you can go to functionhealth.com/huberman.

Function 目前有超过 25 万人的等待名单，但他们正在为 Huberman 播客的听众提供优先访问权限。

Function currently has a wait list of over 250,000 people, but they're offering early access to Huberman podcast listeners.

再次提醒，访问 functionhealth.com/huberman 以获取 Function 的优先访问权限。

Again, that's functionhealth.com/huberman to get early access to function.

现在让我再进一步说明一下。

Now let me just take it one step further.

这些糖分子激活了这一独特的肠脑回路，从而推动了我们对糖的偏好形成。

This now sugar molecules activates this unique gut brain circuit that now drives the development of our preference for sugar.

这一回路的关键在于，肠道中识别糖的传感器无法识别人工甜味剂。

A key element of this circuit is that the sensors in the gut that recognize the sugar do not recognize artificial sweeteners.

这是一种完全不同的分子，只识别葡萄糖分子，而不识别人工甜味剂。

It's a completely different molecule that only recognizes the glucose molecule, not artificial sweeteners.

这对人工甜味剂在抑制我们食欲、渴望以及对糖的无穷欲望方面产生了深远影响。

This has a profound impact on the effect of ultimately artificial sweeteners in curbing our appetite, our craving, our insatiable desire for sugar.

由于它们无法激活肠脑轴，因此永远无法像糖那样满足我们对糖的渴望。

Since they don't activate the gut brain axis, they'll never satisfy the craving for sugar like sugar does.

我们面临着糖和脂肪摄入过量的严重问题。

We have a mega problem with overconsumption of sugar and fat.

我们正处在一个独特的时代，营养不良的疾病是由营养过剩引起的。

We're facing a unique time in our evolution where diseases of malnutrition are due to overnutrition.

历史上，营养不良的疾病一直与营养不足相关。

Historically, diseases of malnutrition have always been linked to undernutrition.

但我想再回到一个观点，即这些大脑中枢最终是被这些必需营养素激活的。

But I want to just go back to the notion of, you know, these brain centers that are ultimately the ones that are being activated by these essential nutrients.

因此，糖、脂肪和氨基酸是我们饮食的基本组成成分，这一点适用于所有动物物种。

So, sugar, fat, and amino acids are building blocks of our diets, and this is across all animal species.

因此，假设大脑中存在专门的回路来确保我们识别、摄入这些物质并强化其必要性，这并不为过。

So it's not unreasonable then to assume that dedicated brain circuits would have evolved to ensure their recognition, their ingestion, and the reinforcement that that is what they need.

事实上，动物进化出了这两种系统。

And indeed, you know, animals evolve these two systems.

一种是味觉系统，让你能够识别它们并触发预先设定的、固有的即时反应，对吧？

One is the taste system that allows you to recognize them and trigger this predetermined hardwired immediate responses, yes?

你会说，天啊，这太美味了，脂肪含量高，或者鲜味，能识别出氨基酸。

You know, oh my god, this is so delicious, it's fatty, or umami, recognizing amino acids.

所以这是味觉通路，对吧？

So that's the lichen pathway, yeah?

但在进化的智慧中，这很好，但还不够。

But in the wisdom of evolution, that's good but doesn't quite do it.

你希望确保这些物质能到达它们真正需要的地方。

You want to make sure that these things get to the place where they are needed.

它们需要进入你的肠道，在那里被吸收为支持生命所需的营养素，而大脑需要知道这一点。

They are needed in your intestines where they are going to be absorbed as the nutrients that will support life, and the brain wants to know this.

高度加工的食品正在劫持、利用这些通路，这种方式在自然界中永远不会发生，于是我们不仅觉得这些食物诱人可口，而且还不断强化对它们的渴望，天啊，这太棒了，我想吃点什么？

Highly processed foods are hijacking, you know, co opting these circuits in a way that it would have never happened in nature, and then we not only find these things appetitive and palatable, but in addition, we are continuously reinforcing the wanting in a way that, oh my God, this is so great, what do I feel like eating?

让我再多吃一点。

Let me have more of this.

这就是为什么我认为现在越来越多的数据开始支持这样一个观点：尽管热力学定律适用，但摄入的卡路里与消耗的卡路里确实是实实在在的，对吧？

This is why I think a lot of data are now starting to support the idea that while indeed the laws of thermodynamics apply, calories ingested versus calories burned is a very real thing, right?

对某些食物的食欲、渴望和喜好是神经系统、大脑和肠道的现象，正如你精彩描述的那样，而且这些会随着时间推移，根据我们接收营养的方式而发生变化。

The appetite for certain foods and the wanting and the liking are phenomena of the nervous system, brain and gut, as you've beautifully described, and that that changes over time depending on how we are receiving these nutrients.

完全正确。

Absolutely.

理解这些神经回路正在为我们提供重要的洞见，最终有望改善人类健康，产生切实的影响。

Understanding these circuits is giving us important insights and how ultimately, hopefully, we can improve human health and make a meaningful difference.

现在，人们很容易试图把点连起来，A到B，B到C，C到D，但我觉得实际情况要复杂得多；不过，我确实认为，从理解这些回路如何运作中得出的教训，最终能帮助我们调整饮食方式，避免我们现在作为社会所面临的困境。

Now, it's very easy to try to, you know, connect the dots, A to B, B to C, C to D, and I think there's a lot more complexity to it, but I do think that the lessons that are emerging out of understanding how these circuits operate can ultimately inform how we deal with our diets in a way that we avoid what we're facing now, you know, as a society.

简直荒谬，营养过剩竟然会成为如此普遍的问题。

I mean, it's nuts that the over nutrition happens to be such a prevalent problem.

是的，而且我认为，研究代谢科学和代谢疾病的人，其训练往往与神经科学家的训练完全脱节，反之亦然。

Yeah, and I also think the training of people who are thinking about metabolic science and metabolic disease is largely divorced from the training of the neuroscientists and vice versa.

没有哪个领域该独自承担责任，但我完全同意，大脑是关键，更准确地说，神经系统是被严重忽视的关键因素之一。

No one field is to blame, but I fully agree that the brain is the key, or the nervous system, to be more accurate, is one of the key overlooked features.

最终，意志力是许多这些通路的裁决者。

Is the arbitrary, ultimately is the arbiter of many of these pathways.

我代表我自己，也代表所有听众，首先感谢您多年来在视觉、味觉以及我们如何感知和体验生活这一更大议题上所做出的卓越工作。

On behalf of myself, and certainly on behalf of all the listeners, I want to thank you, first of all, for the incredible work that you've been doing now for decades in vision, in taste, and in this bigger issue of how we perceive and experience life.

这确实是开创性且令人惊叹的成就，我感到非常幸运，多年来能站在一旁见证这一切，聆听您的演讲，阅读您无数篇优美的论文；同时也感谢您今天抽出时间来到这里，与我们分享驱动您前进的动力以及您所取得的发现。

It's truly pioneering and incredible work, and I feel quite lucky to have been on the sidelines seeing this over the years and hearing the talks and reading the countless beautiful papers, but also for your time today to come down here and talk to us about what drives you and the discoveries you've made.

非常非常感谢您。

Thank you ever so much.

这真是一次愉快的交流。

It was great fun.

谢谢您邀请我。

Thank you for having me.

我们再做一次吧。

We'll do it again.

好吧，祝大家一切顺利。

All right, wish all.