美国国家公共电台 NPR 科学家在苍蝇和老鼠身上发现了人类情绪的根源（在线收听）

In jumpy flies and fiery mice, scientists see the roots of human emotions

科学家在苍蝇和老鼠身上发现了人类情绪的根源

Transcript

We humans often say that a growling dog is "angry" or a purring cat is "happy."

我们人类经常说，咆哮的狗是“愤怒”的，或者咕噜咕噜的猫是“快乐”的

But those terms are of little use to scientists like David Anderson, a biology professor at Caltech who studies the brain circuits involved in emotional behaviors. "We have to do more than just project our own emotions onto other animals," he says, "because animals are not little people in furry costumes."

但这些术语对加州理工学院生物学教授大卫·安德森（David Anderson）这样的科学家来说用处不大，他研究了情绪行为中的大脑回路。“我们必须做的不仅仅是将自己的情绪投射到其他动物身上，”他说，“因为动物不是穿着毛茸茸的衣服的小人物。”

And animals can't tell us how they feel. Yet Anderson believes a connection exists between animal and human emotions.

动物无法告诉我们他们的感受。然而，安德森认为动物和人类的情感之间存在着联系。

"Emotions are brain functions that evolved over time by natural selection," he says. "They didn't just appear on the planet with the advent of Homo sapiens."

“情绪是大脑的功能，随着时间的推移，通过自然选择而进化，”他说。“他们不仅仅是随着智人的出现出现在这个星球上。”

That idea is central to Anderson's latest book, The Nature of the Beast: How Emotions Guide Us. It's also central to a growing scientific effort to find new treatments for disorders like PTSD by manipulating emotion-related brain circuits in animals.

安德森的最新著作《野兽的本质：情绪如何引导我们》（The Nature of The Beast：How Emotions Guide Us）就是以这一观点为核心的。这也是一项日益增长的科学努力的核心，该努力旨在通过操纵动物的情绪相关脑回路来寻找PTSD等疾病的新治疗方法。

In his book, Anderson describes research from his lab that suggests the brain circuits underlying human emotions have a lot in common with circuits found in mice and even fruit flies.

在他的书中，安德森描述了他的实验室的研究表明，人类情绪的大脑回路与老鼠甚至果蝇的回路有很多共同之处。

Feelings versus emotions

感觉与情绪

To study emotions in animals, Anderson says scientists first need to set aside their own perceptions of what people typically think of as emotions, such as anger, fear, sadness or joy.

安德森说，为了研究动物的情绪，科学家首先需要抛开自己对人们通常认为的情绪的看法，比如愤怒、恐惧、悲伤或喜悦。

In other words, they need to look beyond human feelings.

换句话说，他们需要超越人类的感受。

"The feeling part is just the tip of the iceberg, above the sea of our consciousness," Anderson says. "The part below is what we share in common with animals."

安德森说：“感觉部分只是冰山一角，在我们意识的海洋之上。”。“以下部分是我们与动物的共同点。”

What lies beneath feelings, he says, are brain states that produce certain behaviors. And that's the part of emotion that scientists can study. For example, Anderson's lab has investigated fruit flies that become much more active when they see a moving shadow like the one cast by a flying predator.

他说，在情感之下的是产生某些行为的大脑状态。这是科学家可以研究的情感部分。例如，安德森的实验室研究了果蝇，当它们看到像飞行捕食者投射的移动阴影时，它们会变得更加活跃。

"We see that the more times we deliver the shadow, the more jumpy the flies become, until they're literally hopping around like popcorn," he says.

他说：“我们看到，我们投下阴影的次数越多，苍蝇就越害怕，直到它们像爆米花一样到处乱跳。”。

And the flies keep hopping long after the shadow is gone.

在阴影消失很久之后，苍蝇一直在跳。

Anderson would behave much the same way if he were on a hike and saw a rattlesnake.

如果安德森在远足时看到响尾蛇，他也会表现得很像。

"I'd jump in the air," he says. "But even for minutes after the snake had slithered away into the bushes, my heart would be pounding, my mouth would be dry and I'd probably jump every time I saw a snakelike object in front of me — even if it was a stick."

“我会跳到空中，”他说。“但即使在蛇滑进灌木丛后的几分钟里，我的心也会怦怦直跳，嘴巴也会干涩，每当我看到面前有一个蛇形物体时，我可能会跳起来——即使是一根棍子。”

That sort of behavior is typical of a persistent brain state called defensive arousal. It's present in both fruit flies and people, which is why Anderson believes studying fear in an insect or a mouse can reveal a lot about human emotions.

这种行为是一种被称为防御性唤醒的持续大脑状态的典型表现。它存在于果蝇和人身上，这就是为什么安德森认为研究昆虫或老鼠的恐惧可以揭示很多人类情绪。

"We can try to figure out how the brain is generating that state and what makes it last so long and what makes the animal finally calm down," Anderson says.

安德森说：“我们可以尝试弄清楚大脑是如何产生这种状态的，是什么让它持续这么长时间，是什么使动物最终平静下来。”。

In mice, the answer appears to be specialized brain cells that become hyperactive when a mouse detects a threat and that return gradually to normal after the threat has passed. Anderson suspects people have a similar group of cells that generate the feeling we know as fear.

在老鼠身上，答案似乎是当老鼠检测到威胁时变得异常活跃的特殊脑细胞，在威胁过去后逐渐恢复正常。安德森怀疑人们也有类似的细胞群，产生我们所知的恐惧感。

Aggression across species

跨物种攻击

Another human feeling that probably has its roots in animal emotion is anger.

另一种可能源于动物情感的人类情感是愤怒。

There's no way to know if animals have angry feelings, says Dayu Lin, a neuroscientist at New York University. But the sort of aggressive behavior associated with human anger can be found in fish, reptiles, birds and mammals.

纽约大学神经科学家林大宇（Dayu Lin）表示，没有办法知道动物是否有愤怒的情绪。但这种与人类愤怒相关的攻击行为在鱼类、爬行动物、鸟类和哺乳动物身上都可以找到。

So Lin has been studying the brain areas involved in aggression. And she has found one that appears to be critical.

所以林一直在研究与攻击有关的大脑区域。她发现了一个似乎很关键的问题。

"It's a tiny, tiny region deep in the brain, and we all have it," she says.

她说：“这是大脑深处一个非常小的区域，我们都有。”。

In people, this region is near the bottom of the hypothalamus, just above the pituitary gland. And studies show that in mice and other animals, this clump of brain cells is part of a core aggression circuit.

在人类中，这个区域靠近下丘脑的底部，就在脑垂体的上方。研究表明，在小鼠和其他动物身上，这群脑细胞是核心攻击回路的一部分。

"We can evoke aggression by just artificially activating this area in the rodents," Lin says.

林说：“我们可以通过人为激活啮齿类动物的这一区域来唤起攻击性。”。

Switch it on and a mouse will attack. Switch it off and even an animal's natural aggression vanishes. There's some evidence that this can also happen in people. Doctors sometimes use deep brain stimulation to deactivate the aggression circuit in extremely violent psychiatric patients.

打开它，鼠标就会攻击。关掉它，甚至动物的自然攻击性也会消失。有证据表明，这也可能发生在人身上。医生有时会使用脑深部刺激来消除极度暴力的精神病患者的攻击回路。

"Usually the aggression is uncontrollable," Lin says. "That's usually the last resort."

“通常这种攻击是无法控制的，”林说。“这通常是最后的手段。”

Trauma, fear and PTSD

创伤、恐惧和创伤后应激障碍

Animal emotions are also helping scientists understand certain psychiatric disorders, including post-traumatic stress disorder (PTSD).

动物情绪也有助于科学家理解某些精神疾病，包括创伤后应激障碍（PTSD）。

"We really see PTSD as a disorder in which this evolved, important fear response has essentially gone too far,'' says Dr. Kerry Ressler of Harvard Medical School and McLean Hospital.

哈佛医学院和麦克莱恩医院的凯瑞·雷斯勒博士说：“我们真的认为PTSD是一种疾病，在这种疾病中，这种进化的、重要的恐惧反应基本上已经走得太远了。”。

For a person with PTSD, even a minor event can produce a stress and fear response that lasts for hours, Ressler says. And there's a parallel in animals.

雷斯勒说，对于患有PTSD的人来说，即使是轻微的事件也会产生持续数小时的压力和恐惧反应。在动物身上也有类似的现象。

A typical mouse will freeze when it hears a tone associated with a mild electric shock. But if the shocks stop coming, the animal soon learns to ignore the tone.

一只典型的老鼠在听到轻微电击的声音时会冻僵。但如果电击停止，动物很快就会学会忽略音调。

Trauma changes that learning curve.

创伤改变了学习曲线。

"If the animal's had prior trauma, they'll learn more quickly, they'll freeze for longer and it takes them longer to extinguish or learn that that tone is actually safe," Ressler says.

雷斯勒说：“如果动物之前受过创伤，他们会更快地学会，他们会冷冻更长时间，需要更长时间才能熄灭或了解到这种音调实际上是安全的。”。

In both people and mice, trauma appears to alter a brain circuit involving the amygdala and the prefrontal cortex. And in rodents, it's possible to regulate that circuit.

在人和小鼠中，创伤似乎改变了涉及杏仁核和前额叶皮层的大脑回路。在啮齿类动物身上，可以调节这种回路。

"We now understand specific parts of the circuit that increase fear and other parts of the circuit that decrease fear," or at least the animal version of that emotion, Ressler says.

雷斯勒说：“我们现在了解了回路中增加恐惧的特定部分，以及回路中减少恐惧的其他部分，”或者至少是这种情绪的动物版本。

The next step, he says, is to figure out how to tweak that circuit to reduce the fear response in people with PTSD.

他说，下一步是找出如何调整这个电路，以减少PTSD患者的恐惧反应。