What happens in your brain when you taste food | Camilla Arndal Andersen

Translator: Ivana Korom Reviewer: Krystian Aparta

翻译人员: Xiaowei Dong 校对人员: Yolanda Zhang

So I had this very interesting experience

五年前，我碰到了

five years ago.

一件有趣的事儿。

You know, me and my husband, we were out grocery shopping,

有一天，和往常一样，

as we do every other day,

我和我丈夫去买菜，

but this time, we found this fancy,

但这次我们看到了 一家特别高大上的店，

you know, I'm talking fair-trade, I'm talking organic,

有这么一类公平贸易、有机，

I'm talking Kenyan, single-origin coffee

来自肯尼亚单一产区的咖啡，

that we splurged and got.

我们买了好多。

And that was when the problem started already.

这时候问题就来了。

You know, my husband, he deemed this coffee blend superior

我丈夫觉得买的这类咖啡

to our regular and much cheaper coffee,

比平常普通便宜的咖啡要好喝，

which made me imagine a life based solely on fancy coffee

我不禁想象了一下 只有高档格咖啡的生活，

and I saw our household budget explode.

以我们的经济状况肯定吃不消。

(Laughter)

（笑）

And worse ...

更重要的是，

I also feared that this investment would be in vain.

我更担心这类投资没什么意义。

That we wouldn't be able to notice this difference after all.

毕竟我们根本喝不出来区别。

Unfortunately, especially for my husband,

不巧的是，我丈夫

he had momentarily forgotten that he's married to a neuroscientist

时常忘记他的妻子 是一位神经科学家，

with a specialty in food science.

专长是食品科学。

(Laughter)

（笑声）

Alright?

就是这么个情况。

So without further ado,

那么事不宜迟，

I mean, I just put him to the test.

我赶忙丢给他一个测试。

I set up an experiment

我设置了一个实验，

where I first blindfolded my husband.

也就是把我丈夫的眼睛蒙上。

(Laughter)

(笑声)

Then I brewed the two types of coffee

然后冲泡了两种咖啡，

and I told him that I would serve them to him

并告诉他

one at a time.

我一次给他喝一种。

Now, with clear certainty,

我的丈夫在描述

my husband, he described the first cup of coffee

第一杯咖啡的时候十分肯定地说，

as more raw and bitter.

这杯更苦更涩。

You know, a coffee that would be ideal for the mornings

就是那种一大早起床

with the sole purpose of terrorizing the body awake by its alarming taste.

能让人立马清醒的味道。

(Laughter)

（笑声）

The second cup of coffee, on the other hand,

而第二杯咖啡，他说

was both fruity and delightful.

更令人愉悦，还带些果味，

You know, coffee that one can enjoy in the evening and relax.

是适合晚上喝的那种咖啡。

Little did my husband know, however,

但我的丈夫并不知道

that I hadn't actually given him the two types of coffee.

我其实根本没有给他喝两种咖啡，

I had given him the exact same cup of coffee twice.

而是同一杯咖啡给他喝了两次。

(Laughter)

（笑声）

And obviously, it wasn't this one cup of coffee

显然，并不是这一杯咖啡

that had suddenly gone from horrible to fantastic.

突然变得好喝，

No, this taste difference was a product of my husband's own mind.

而是我丈夫的心理作用。

Of his bias in favor of the fancy coffee

因为他对来自肯尼亚单一产区 的有机咖啡的偏好

that made him experience taste differences that just weren't there.

让他体会到了本不存在的味觉差异。

Alright, so, having saved our household budget,

所以呢，我轻而易举地 省下了家庭开支，

and finishing on a very good laugh,

还逗得大家笑了笑。

me especially --

我呢——

(Laughter)

（笑声）

I then started wondering just how we could have received

开始思索我们

two such different responses from a single cup of coffee.

是如何接收两种不同信息的。

Why would my husband make such a bold statement

为什么我的丈夫可以充满信心的作答

at the risk of being publicly mocked for the rest of his life?

而不怕被人在公共场合嘲笑呢？

(Laughter)

（笑声）

The striking answer is that I think you would have done the same.

别笑，其实大家都一样。

And that's the biggest challenge in my field of science,

而这也是我这门学科最大的挑战，

assessing what's reality behind these answers

即这些答案背后的真相

that we receive.

是什么。

Because how are we going to make food tastier

因为如果我们都不能相信人们说的话，

if we cannot rely on what people actually say they like?

又该怎么才能让食物变好吃呢？

To understand, let's first have a look at how we actually sense food.

要想一探究竟，我们还得来看看 人类是如何感知食物的。

When I drink a cup of coffee,

当我喝咖啡的时候，

I detect this cup of coffee by receptors on my body,

身体中的受体分子会感知到，

information which is then turned into activated neurons in my brain.

接着信息便会传到活跃的大脑神经元。

Wavelengths of light are converted to colors.

光波被转化为颜色。

Molecules in the liquid are detected by receptors in my mouth,

嘴巴里的受体感知到液体分子

and categorized as one of five basic tastes.

然后把它们归类为五种基本味道，

That's salty, sour, bitter, sweet and umami.

即酸，甜，苦，咸，鲜。

Molecules in the air are detected by receptors in my nose

鼻子里的受体会感知空气分子

and converted to odors.

并转化为香味。

And ditto for touch, for temperature, for sound and more.

这些也适用于触摸，温度，声音等等。

All this information is detected by my receptors

这一切信息都会被身体里 的接受体检测到，

and converted into signals between neurons in my brain.

并转化为大脑神经元之间的信号，

Information which is then woven together and integrated,

然后信息被编码并组合，

so that my brain recognizes

这样大脑就可以识别出

that yes, I just had a cup of coffee, and yes, I liked it.

刚刚喝了杯咖啡，还蛮喜欢的。

And only then,

只有在

after all this neuron heavy lifting,

所有神经元都干完活后

do we consciously experience this cup of coffee.

我们才能有意识地去体会这杯咖啡。

And this is now where we have a very common misconception.

这时人们常常有些误解。

People tend to think that what we experience consciously

人们总觉得我们有意识感知到的东西

must then be an absolute true reflection of reality.

一定反映出了绝对的现实。

But as you just heard,

但正如我刚刚所说的，

there are many stages of neural interpretation

神经解释在实物 和有意识的经验之间

in between the physical item and the conscious experience of it.

有很多步骤，

Which means that sometimes,

也就是说，有的时候，

this conscious experience is not really reflecting that reality at all.

有意识的体验并不一定 能反应出真实情况。

Like what happened to my husband.

正如我的丈夫一样。

That's because some physical stimuli may just be so weak

这是因为一些物理刺激可能太过微弱，

that they just can't break that barrier to enter our conscious mind,

并不能打破重重关卡 最后进入我们的意识之中，

while the information that does

而这个信息

may get twisted on its way there by our hidden biases.

则会被隐藏的偏见所扭曲。

And people, they have a lot of biases.

人类有太多偏见。

Yes, if you're sitting there right now, thinking ...

没错，如果你在想，

you could probably have done better than my husband,

你肯定不会和我丈夫一样，

you could probably have assessed those coffees correctly,

并能辨别出这只是同一杯咖啡，

then you're actually suffering from a bias.

那你可能的确有一种偏见，

A bias called the bias blind spot.

即偏见盲点。

Our tendency to see ourselves as less biased than other people.

我们经常认为自己没有 别人那么多的偏见。

(Laughter)

（笑声）

And yeah, we can even be biased

没错， 我们甚至可能因为

about the biases that we're biased about.

我们有偏见的偏见而有偏见。

(Laughter)

（笑声）

Not trying to make this any easier.

再往前一步说，

A bias that we know in the food industry is the courtesy bias.

食品业中常见的，是礼貌性偏见。

This is a bias where we give an opinion

这种偏见是，我们给出一个

which is considered socially acceptable,

社会上普遍认可的观点，

but it's certainly not our own opinion, right?

但这绝对不是我们自己的观点。

And I'm challenged by this as a food researcher,

作为一名食品科学家， 我对此不以为然，

because when people say they like my new sugar-reduced milkshake,

当人们说他们喜欢我手里 的低糖奶昔的时候，

do they now?

是真心的吗？

(Laughter)

（笑）

Or are they saying they like it

还是说，

because they know I'm listening and they want to please me?

他们只是知道我在听这些话， 而他们只想逗我开心？

Or maybe they just to seem fit and healthy in my ears.

又或者他们只想 让我觉得他们挺健康的，

I wouldn't know.

谁知道呢。

But worse, they wouldn't even know themselves.

更有趣的是，他们可能 并没有意识到自己的行为。

Even trained food assessors,

甚至经过严格训练

and that's people who have been explicitly taught

的食品评估者，那些经过特殊训练

to disentangle the sense of smell and the sense of taste,

学习如何分别味觉和嗅觉的人，

may still be biased to evaluate products sweeter

都会因为食物里有香草

if they contain vanilla.

更认为这份食物比较甜。

Why?

为什么？

Well, it's certainly not because vanilla actually tastes sweet.

当然这不是因为香草真的比较甜。

It's because even these professionals are human,

而是因为这些专家都是人，

and have eaten lot of desserts, like us,

和我们一样吃了很多甜点

and have therefore learned to associate sweetness and vanilla.

并因此将甜度和香草联系在了一起。

So taste and smell and other sensory information

所以味觉嗅觉和其他感官

is inextricably entangled in our conscious mind.

在我们的意识中是难以分割的。

So on one hand, we can actually use this.

所以一方面讲，我们可以利用

We can use these conscious experiences,

这些有意识的体验，

use this data, exploit it by adding vanilla instead of sugar

这些数据， 来研究加多少香草来代替糖

to sweeten our products.

去增加食品的甜度。

But on the other hand,

但另一方面，

with these conscious evaluations,

有了这些有意识的评估，

I still wouldn't know

我还是不知道

whether people actually liked that sugar-reduced milkshake.

到底人们是不是真的喜欢低糖奶昔。

So how do we get around this problem?

那我们该如何解决这个问题呢？

How do we actually assess what's reality

如何区分有意识的食品评估

behind these conscious food evaluations?

背后的真相呢？

The key is to remove the barrier of the conscious mind

关键在于要移除意识的重重阻拦，

and instead target the information in the brain directly.

直接尝试去获取大脑中的信息。

And it turns out

事实证明，

our brain holds a lot of fascinating secrets.

我们的大脑藏有许多不为人知的秘密。

Our brain constantly receives sensory information from our entire body,

大脑通常接收来自全身的感知信息。

most of which we don't even become aware of,

多半我们都没有意识到，

like the taste information that I constantly receive

比如胃肠道的

from my gastrointestinal tract.

味道信息。

And my brain will also act on all this sensory information.

大脑会自动处理这些味道信息，

It will alter my behavior without my knowledge,

会在人们没有意识到 的情况下改变行为，

and it can increase the diameter of my pupils

并扩大瞳孔，

if I experience something I really like.

仿佛我们真的经历了喜欢的事情一样。

And increase my sweat production ever so slightly

这个反应还会在情绪激动的时候

if that emotion was intense.

提高汗液产出。

And with brain scans,

大脑扫描

we can now assess this information in the brain.

为我们提供了大脑中的这些信息。

Specifically, I have used a brain-scanning technique

我所用的一种大脑扫描技术

called electroencephalography,

叫脑电图，

or "EEG" in short,

即EEG，

which involves wearing a cap studded with electrodes,

这个过程要求人们带上一顶

128 in my case.

带有128个电极的帽子。

Each electrode then measures the electrical activity of the brain

每个电极都会测量大脑的电活动，

with precision down to the millisecond.

精确到毫秒。

The problem is, however,

然而问题是，

it's not just the brain that's electrically active,

并不只有大脑才有电活动，

it's also the rest of the body as well as the environment

人的全身，包括周遭环境

that contains a lot of electrical activity all the time.

都包含许多电活动。

To do my research,

为了完成研究，

I therefore need to minimize all this noise.

我得尽力去除这些外界因素影响。

So I ask my participants to do a number of things here.

所以我让实验者做了如下一些事。

First off,

第一，

I ask them to rest their head in a chin rest,

我让他们把头放到腮托上，

to avoid too much muscle movement.

尽量避免肌肉活动。

I also ask them to, meanwhile, stare at the center of a computer monitor

我还让他们盯着电脑中央，

to avoid too much eye movements and eye blinks.

以避免过多的眼球转动及眨眼。

And I can't even have swallowing,

甚至还不能咽口水，

so I ask my participants to stick the tongue out of their mouth

所以我让他们把舌头伸出来

over a glass bowl,

放到玻璃碗上，

and then I constantly let taste stimuli onto the tongue,

并不停放上味觉刺激物，

which then drip off into this bowl.

然后他们的口水就可以滴到碗里。

(Laughter)

（笑声）

And then, just to complete this wonderful picture,

之后，为了画龙点睛，

I also provide my participants with a bib,

我还给了他们一个围兜，

available in either pink or blue, as they please.

蓝色或粉色，随他们挑。

(Laughter)

（笑声）

Looks like a normal eating experience, right?

看起来就像是个 正常进食活动，对吧？

(Laughter)

（笑声）

No, obviously not.

才怪。

And worse,

而且，

I can't even control what my participants are thinking about,

因为我无法控制他们的想法，

so I need to repeat this taste procedure

所以得不停重复这个实验

multiple times.

很多次。

Maybe the first time, they're thinking about the free lunch

或许第一次，他们在想我提供的

that I provide for participating,

免费午餐，

or maybe the second time, they're thinking about Christmas coming up

第二次，在想即将到来的圣诞

and what to get for Mom this year, you know.

得给妈妈买什么。

But common for each response is the response to the taste.

但每次都是对味道的反应

So I repeat this taste procedure multiple times.

所以我不停重复这些步骤。

Sixty, in fact.

重复了六十次。

And then I average the responses,

然后对实验结果去了平均值，

because responses unrelated to taste will average out.

因为那些无关味觉的都可以被平均掉。

And using this method,

用了这个办法，

we and other labs,

我和其他实验室

have investigated how long a time it takes from "food lands on our tongue"

研究了从“食物碰到舌头”，

until our brain has figured out which taste it's experiencing.

到大脑终于弄明白那是什么样的味道 需要多久。

Turns out this occurs within the first already 100 milliseconds,

我们发现，整个过程发生在前100毫秒，

that's about half a second before we even become aware of it.

也就是我们有所感知之前半秒钟。

And next up, we also investigated

之后，我们还研究了

the taste difference between sugar and artificial sweeteners

糖和其他人工甜味剂的味觉差异，

that in our setup taste extremely similar.

发现并无不同。

In fact, they tasted so similar

甚至可以说，

that half my participants could only barely tell the taste apart,

半数的受试者都很难区分，

while the other half simply couldn't.

而另一半则完全无法区分。

But amazingly,

最令人惊叹的是，

if we looked across the entire group of participants,

如果我们将整组受试者进行比较，

we saw that their brains definitely could tell the taste apart.

他们的大脑绝对可以识别差异。

So with EEG and other brain-scanning devices

所以有了脑电图和其他大脑扫描设备

and other physiological measures --

及其他生理测试的辅助——

sweat and pupil size --

研究汗液和瞳孔——

we have new gateways to our brain.

我们走上了通往大脑的新道路。

Gateways that will help us remove the barrier of the conscious mind

这条路可以帮助我们免去意识的屏障，

to see through the biases of people

看穿人类的偏见，

and possibly even capture subconscious taste differences.

甚至还能捕捉潜意识中的味道差异。

And that's because we can now measure people's very first response to food

这是因为现在我们可以测量 人体对食物的第一反应，

before they've become conscious of it,

甚至先于人类的自我认知，

and before they've started rationalizing why they like it or not.

在他们开始思索到底喜不喜欢之前。

We can measure people's facial expressions,

我们可以研究人的面部表情，

we can measure where they're looking,

他们在看哪，

we can measure their sweat response,

可以研究汗液反应，

we can measure their brain response.

大脑反应。

And with all these measures,

所有的这些测试

we are going to be able to create tastier foods,

都能帮助我们创造更好吃的食物，

because we can measure whether people actually like

因为我们能知道人们究竟喜不喜欢

that sugar-reduced milkshake.

那杯低糖奶昔。

And we can create healthier foods without compromising taste,

我们还能在不影响味道 的前提下产出更健康的食品，

because we can measure the response to different sweeteners

因为我们可以研究人们 对不同甜味剂的反应，

and find the sweetener that gives the response that's more similar

并找出哪一种

最接近糖。

to the response from sugar.

And furthermore, we can just help create healthier foods,

进一步讲，我们可以 生产出更健康的食物，

because we can help understand how we actually sense food

因为我们能帮助人们理解

in the first place.

人类是如何感知食物的。

Which we know surprisingly little about.

这点我们知之甚少。

For example, we know that there are those five basic tastes,

比如，我们知道最基本的五种味道，

but we strongly suspect that there are more,

但并不知道还有更多的味道，

and in fact, using our EEG setup, we found evidence that fat,

事实上，利用脑电图，我们发现

besides being sensed by its texture and smell,

脂肪，除了它的气味和质地，

is also tasted.

也是有味道的。

Meaning that fat could be this new sixth basic taste.

也就是说我们有了第六种基本味道，

And if we figure out how our brain recognizes fat and sugar,

并且如果我们能知道大脑 是如何识别脂肪和糖分的话，

and I'm just dreaming here,

做个比方，

but could we then one day

那是不是意味着有朝一日，

create a milkshake with zero calories that tastes just like the real deal?

我们能制造出零卡路里的“原味”奶昔？

Or maybe we figure out that we can't,

或许我们能知道我们做不到，

because we subconsciously detect calories

因为潜意识中检测卡路里的感知器

via our receptors in our gastrointestinal tract.

是胃肠道。

The future will show.

未来我们会得到更加清晰的结论。

Our conscious experience of food

我们对食物的有意识经历

is just the tip of the iceberg of our total sensation of food.

只是我们对食物感知的冰山一角。

And by studying this total sensation,

通过研究全面感知，

conscious and subconscious alike,

不管有意识还是潜意识的，

I truly believe that we can make tastier and healthier foods for all.

我认为我们都可以为人类 创造美味又健康的食物。

Thank you.

谢谢。

(Applause)

（掌声）