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蜻蜓的大脑生来就是杀戮 | DIY神经科学系列 – 译学馆
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蜻蜓的大脑生来就是杀戮 | DIY神经科学系列

How a dragonfly's brain is designed to kill | DIY Neuroscience, a TED series

翻译:约瑟夫·杰尼 评论:乔安娜·皮埃储勒维科兹
Translator: Joseph GeniReviewer: Joanna Pietrulewicz
格雷格·盖奇:
Greg Gage:
如果我要你想一个夺命猛兽
If I asked you to think of a ferocious killer animal,
你可能会想起狮子
you’d probably think of a lion,
尽管狮子有所有令人惊奇的捕食技能
and for all the wonderful predatory skills that a lion has,
它只有20%抓住猎物饱餐一顿的成功率
it still only has about a 20 percent success rate at catching a meal. Now,
现在 令人惊讶的是
one of the most successful hunters
整个动物王国里最成功的捕猎者是蜻蜓
in the entire animal kingdom is surprising: the dragonfly.
蜻蜓是夺命两翼昆虫 看到较小的两翼昆虫时
Dragonflies are killer flies, and when they see a smaller fly,
它们有97%抓住猎物饱餐一顿的机会
they have about a 97 percent chance of catching it for a meal.
这只正在飞行中
And this is in mid-flight.
但这么小的昆虫如何做到如此精准呢?
But how can such a small insect be so precise?
在这一集 我们会看到
In this episode, we’re going to see
蜻蜓的大脑是如何专门成为致命杀手的
how the dragonfly’s brain is highly specialized to be a deadly killer.
(神经系统科学)
[DIY Neuroscience]
那么 是什么使蜻蜓
So what makes the dragonfly
成为动物王国最成功的捕猎者的?
one of the most successful predators in the animal kingdom?
第一是它们的眼睛
One, it’s the eyes.
有将近360度的视野
It has near 360-degree vision.
第二是翅膀
Two, the wings.
蜻蜓能控制单个翅膀
With individual control of its wings,
可以精准地向任一方向移动
the dragonfly can move precisely in any direction.
但是 蜻蜓成功的真正秘诀是
But the real secret to the dragonfly’s success
它的大脑如何协调眼睛和翅膀之间的
is how its brain coordinates this complex information
复杂信息以及把捕猎变为简单的本能反应
between the eyes and the wings and turns hunting into a simple reflex.
为了研究这些 杰米花费了大量的时间
To study this, Jaimie’s been spending a lot of time
与蜻蜓交流
socializing with dragonflies.
做你的实验都需要什么?
What do you need to do your experiments?
首先 你需要蜻蜓
First of all, you need dragonflies.
我用一个网兜去捕捉蜻蜓
I have a mesh cage to catch the dragonflies.
我对着它们工作越久 越害怕它们
The more I worked to them, the more terrified I got of them.
它们实际上很可怕 尤其在显微镜下
They’re actually very scary, especially under a microscope.
它们有非常锋利的上颚 通常很具攻击性
They have really sharp mandibles,are generally pretty aggressive,
我觉得这会帮助它们成为好的捕猎者
which I guess also helps them to be really good predators.
格雷格·盖奇:为了了解
In order to learn what’s going on
蜻蜓看到猎物时 其大脑的内部变化
inside the dragonfly’s brain when it sees a prey,
我们将会偷听蜻蜓眼睛和翅膀之间
we’re going to eavesdrop in on a conversation
的一段交流
between the eyes and the wings,
要那样做的话
and to do that,
我们需要把蜻蜓麻痹在冰块上
we need to anesthetize the dragonfly on ice
并确保保护好它的翅膀 以便之后放飞
and make sure we protect its wings so that we can release it afterwards.
蜻蜓大脑由名为“神经元”的专门细胞组成
Now, the dragonfly’s brain is made up of specialized cells called neurons
这些神经元能让蜻蜓
and these neurons are what allow the dragonfly
迅速地看见并移动
to see and move so quickly.
个体的神经元通过细长线状的轴突
The individual neurons form circuitsby connecting to each other
连接彼此 形成线路
via long, tiny threads called axons
神经元用电 通过这些轴突交流
and the neurons communicateover these axons using electricity.
我们要在蜻蜓体内顺着轴突放置
In the dragonfly, we’re going to place little metal wires, or electrodes,
小的金属线或电极 这才是真正酷的地方
along the axon tracks, and this is what’s really cool.
蜻蜓体内只有16个神经元
In the dragonfly, there’s only 16 neurons;
每只眼有8个 告诉翅膀目标的确切位置
that’s eight per eye that tell the wings exactly where the target is.
我们已放入了电极
We’ve placed the electrodes so
这样就可以从这些连接
that we can record from these neurons
眼睛和翅膀的神经元把其记录下来
that connect the eyes to the wings.
每当一条信息从眼睛被传至翅膀时
Whenever a message is being passed from the eye to the wing,
电极就会截获以电流形式出现的对话
our electrode intercepts that conversation in the form of an electrical current,
并将其放大
and it amplifies it.
我们能同时听到并看到它以
Now we can both hear it and see it
骤增的形式出现
in the form of a spike,
它也可以被称为动作电位
which we also call an action potential.
现在 我们来听听看
Now let’s listen in.
现在 我们把蜻蜓倒过来
Right now, we have the dragonflyflipped upside down,
让它朝向地面
so he’s looking down towards the ground.
我们将会取出一个猎物
We’re going to take a prey,
或者 有时我们所说的目标
or what we sometimes call a target.
在这种情况下 目标是一只假苍蝇
In this case, the target’s going to be a fake fly.
我们会把目标移至蜻蜓的视野内
We’re going to move it into the dragonfly’s sights.
[嗡嗡声]
(Buzzing)
天啊
Oh! Oh,
看那个
look at that.
看呐 但它只是朝一个方向
Look at that, but it’s only in one direction.
真酷
Oh, yes!
目标往前移动时 你看不到任何骤增
You don’t see any spikes when I go forward,
但往回移动时就出现了
but they’re all when I come back.
在我们的实验里
In our experiments,
我们能看到 向一个方向移动目标时
we were able to see that the neurons of the dragonfly
蜻蜓的神经元就会躁动 反方向则不然
fired when we moved the target in one direction but not the other. Now,
那是为什么?
why is that?
还记得我之前说 蜻蜓有近360度视野
Remember when I said that the dragonfly had near 360-degree vision. Well,
眼睛的一个叫做小凹的部分
there’s a section of the eye called the fovea
有最敏锐的视敏度
and this is the part that has the sharpest visual acuity,
你可以把这部分看作蜻蜓的瞄准器
and you can think of it as its crosshairs.
记得我说过 蜻蜓有精准的单翅控制吗?
Remember when I told you the dragonfly had individual precise control of its wings?
蜻蜓看到猎物时
When a dragonfly sees its prey,
会用它的瞄准器对准猎物
it trains its crosshairs on it
并沿着轴突只给控制翅膀的神经元发送
and along its axons it sends messages only to the neurons that control the parts of the wings
瞄准目标所需的信息
that are needed to keep that dragonfly on target.
所以如果猎物在蜻蜓的左侧
So if the prey is on the left of the dragonfly,
那么只有牵引左翅膀的神经元被发出
only the neurons that are tugging the wings to the left are fired.
如果猎物移至蜻蜓的右侧
And if the prey moves to the right of the dragonfly,
这些同样的神经元不会被激活 将继续保持平静
those same neurons are not needed, so they’re going to remain quiet.
蜻蜓从一个固定的
And the dragonfly speeds toward the prey
由瞄准器带领翅膀的角度
at a fixed angle that’s communicated
朝猎物的方向加速
by this crosshairs to the wings,
然后 嘣的一声 享受晚餐
and then boom, dinner. Now,
这一切都发生在一刹那
all this happens in a split second,
对蜻蜓来说毫不费力
and it’s effortless for the dragonfly.
几乎像一种本能反应
It’s almost like a reflex.
整个非常有效的过程被称为固定
And this whole incredibly efficient process is called fixation.
但整个过程还有一个故事
But there’s one more story to this process.
我们看到神经元是如何对动作做出反应
We saw how the neurons respond to movements,
但蜻蜓怎么知道那东西就是猎物呢?
but how does the dragonfly know that something really is prey?
这就是尺寸的重要之处
This is where size matters.
我们给蜻蜓看一系列的点点
Let’s show the dragonfly a series of dots. Oh,
快看!
yeah! JS:
杰米·斯巴赫:是的 蜻蜓更喜欢那个点
Yeah, it prefers that one. GG:
使用所有尺寸后
Out of all the sizes,
我们发现蜻蜓对较小目标有反应 而非较大的
we found that the dragonfly responded to smaller targets over larger ones.
换句话说
In other words,
蜻蜓天生捕猎较小的两翼昆虫
the dragonfly was programmed to go after smaller flies
而不是较大的 比如鸟类
versus something much larger, like a bird.
一旦蜻蜓把那只可怜的小虫认做猎物
And as soon as it recognizes something as prey,
它便命不久矣
that poor little fly only has seconds to live.
今天 我们看到了蜻蜓的大脑如何工作
Today we got to see how the dragonfly’s brain works
使其成为非常有效率的杀手
to make it a very efficient killer.
我们应该庆幸
And let’s be thankful
自己没有生活在3亿年前
that we didn’t live 300 million years ago
当时的蜻蜓有猫咪那么大
when dragonflies were the size of cats.

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视频概述

蜻蜓为什么会成为动物王国里捕猎成功率最高的动物 以及蜻蜓大脑的构成和运作原理

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视频来源

https://www.youtube.com/watch?v=Y0vRupFPw90

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