I grew up watching Star Trek. I love Star Trek. Star Trek made me want to see alien creatures, creatures from a far-distant world. But basically, I figured out that I could find those alien creatures right on Earth.
我是看《星际迷航》长大的,我非常喜欢 《星际迷航》使得我很想看看外星生物 来自很远很远的世界的生物 但基本上,我发现我可以 在地球上找到这些外星生物
And what I do is I study insects. I'm obsessed with insects, particularly insect flight. I think the evolution of insect flight is perhaps one of the most important events in the history of life. Without insects, there'd be no flowering plants. Without flowering plants, there would be no clever, fruit-eating primates giving TED Talks.
我所做的就是去研究昆虫 我对昆虫着迷,特别是昆虫的飞行 我认为昆虫飞行的进化,也行是 生命历史上一个最重要的事件 如果没有会飞行的昆虫,那就没有有花的植物 没有有花的植物,那也就没有 聪明的,喜欢吃水果的猿长类动物在这里做TED讲座
(Laughter)
(笑声)
Now, David and Hidehiko and Ketaki gave a very compelling story about the similarities between fruit flies and humans, and there are many similarities, and so you might think that if humans are similar to fruit flies, the favorite behavior of a fruit fly might be this, for example -- (Laughter) but in my talk, I don't want to emphasize on the similarities between humans and fruit flies, but rather the differences, and focus on the behaviors that I think fruit flies excel at doing.
现在 David,Hidehiko和Hetaki 说了一个非常吸引眼球的一个故事 关于果蝇和人类的相似性 相似的地方非常多 你们觉得如果人类和果蝇很相似 那么果蝇最喜欢的动作可能会是这样 (笑声) 但我现在不想强调这个相似性 而是关注相异的地方 关注果蝇擅长的事情
And so I want to show you a high-speed video sequence of a fly shot at 7,000 frames per second in infrared lighting, and to the right, off-screen, is an electronic looming predator that is going to go at the fly. The fly is going to sense this predator. It is going to extend its legs out. It's going to sashay away to live to fly another day. Now I have carefully cropped this sequence to be exactly the duration of a human eye blink, so in the time that it would take you to blink your eye, the fly has seen this looming predator, estimated its position, initiated a motor pattern to fly it away, beating its wings at 220 times a second as it does so. I think this is a fascinating behavior that shows how fast the fly's brain can process information.
所以,我想让你们看一个高速录像 通过每秒7000帧红外拍摄的苍蝇 在屏幕的外的右边,有一只会发电的捕食者 正在靠近这个苍蝇 这个苍蝇会察觉到这个捕食者 然后会拔腿而跑 看似不经已地逃走 再活上一天 我小心地裁剪了这个片子 使得它跟人的眨眼时间一致 使得当你眨眼的时候 这个苍蝇已经看到了捕食者 估计好了它的位置,启动了飞行模式 以每秒220下的速度拍打着翅膀 我觉得这是个让人瞠目结舌的行为 这体现了苍蝇大脑处理信息的速度
Now, flight -- what does it take to fly? Well, in order to fly, just as in a human aircraft, you need wings that can generate sufficient aerodynamic forces, you need an engine sufficient to generate the power required for flight, and you need a controller, and in the first human aircraft, the controller was basically the brain of Orville and Wilbur sitting in the cockpit.
现在,我们来看航行。飞行需要什么? 如果要飞起来,像人造航空器一样 你需要能够产生足够的空气动力的翅膀 你需要一个能够产生足够马力的引擎来支持航行 而且你需要一个控制器 在人类第一个飞行器里,控制器是基本上是 坐在座舱里的Orville和Wilbur的大脑
Now, how does this compare to a fly? Well, I spent a lot of my early career trying to figure out how insect wings generate enough force to keep the flies in the air. And you might have heard how engineers proved that bumblebees couldn't fly. Well, the problem was in thinking that the insect wings function in the way that aircraft wings work. But they don't. And we tackle this problem by building giant, dynamically scaled model robot insects that would flap in giant pools of mineral oil where we could study the aerodynamic forces. And it turns out that the insects flap their wings in a very clever way, at a very high angle of attack that creates a structure at the leading edge of the wing, a little tornado-like structure called a leading edge vortex, and it's that vortex that actually enables the wings to make enough force for the animal to stay in the air. But the thing that's actually most -- so, what's fascinating is not so much that the wing has some interesting morphology. What's clever is the way the fly flaps it, which of course ultimately is controlled by the nervous system, and this is what enables flies to perform these remarkable aerial maneuvers.
这个跟苍蝇比较起来怎样呢? 在我职业生涯的早期,我花了很多时间尝试弄明白 苍蝇的翅膀是怎样提供足够的力量使得它可以悬浮在空中 你也行听工程师们证明过 大黄蜂不会飞 问题是(他们)是用飞行器翅膀的工作原理来解释昆虫翅膀的 而实际上不是这样的 为解决这个问题,我们可以制造巨大的 能够动态伸缩的机器昆虫模型 它会使用大量矿物油来驱动它拍打翅膀 我们就可以从中学习空气动力学 结果是,我们发现昆虫拍打翅膀的方式 很巧妙。 创建一个结构的机翼前沿 称为前缘涡,有点类似龙卷风的结构 这个漩涡实际上让翅膀 可以产生足够的力量让它们悬浮在空中 但最让人着迷的 不是翅膀那有趣的形态学 最聪明的是苍蝇拍打翅膀的方式 它最终还是受控与神经系统 这使得苍蝇可以完成 这些让人叹绝的空中杂技
Now, what about the engine? The engine of the fly is absolutely fascinating. They have two types of flight muscle: so-called power muscle, which is stretch-activated, which means that it activates itself and does not need to be controlled on a contraction-by-contraction basis by the nervous system. It's specialized to generate the enormous power required for flight, and it fills the middle portion of the fly, so when a fly hits your windshield, it's basically the power muscle that you're looking at. But attached to the base of the wing is a set of little, tiny control muscles that are not very powerful at all, but they're very fast, and they're able to reconfigure the hinge of the wing on a stroke-by-stroke basis, and this is what enables the fly to change its wing and generate the changes in aerodynamic forces which change its flight trajectory. And of course, the role of the nervous system is to control all this.
那么,这个引擎怎样呢? 苍蝇的引擎绝对让人着迷 它们有两种用于航行的肌肉 所谓的力量型肌肉,这是舒张时激活的 这意味着它自己激活自己,并不需要被控制于 一个基于收缩的中枢神经系统 它有专门来生成所需的飞行的巨大的力量 它填充着中间的部分 所以,当一只苍蝇撞到你的挡风玻璃, 你看到的基本上它的力量型肌肉 但附加到机翼的基部 是一套的小型的控制肌肉 这不是非常强大,但他们速度非常快, 他们就能够重新配置的机翼转轴 不断拍打的着 这使苍蝇能够改变它的翅膀 并在产生在气动力学上的变化 这改变其飞行轨迹 当然,中枢神经系统的作用是控制所有这一切
So let's look at the controller. Now flies excel in the sorts of sensors that they carry to this problem. They have antennae that sense odors and detect wind detection. They have a sophisticated eye which is the fastest visual system on the planet. They have another set of eyes on the top of their head. We have no idea what they do. They have sensors on their wing. Their wing is covered with sensors, including sensors that sense deformation of the wing. They can even taste with their wings. One of the most sophisticated sensors a fly has is a structure called the halteres. The halteres are actually gyroscopes. These devices beat back and forth about 200 hertz during flight, and the animal can use them to sense its body rotation and initiate very, very fast corrective maneuvers. But all of this sensory information has to be processed by a brain, and yes, indeed, flies have a brain, a brain of about 100,000 neurons.
现在,让我们看看该控制器 现在苍蝇擅长各种传感器 他们引出这一问题 它们身上有天线,能够感觉气味和检测风向 他们的复眼 是这个星球上最快的视觉系统 它们头上有另一套眼睛。 我们也不知道它们用来做什么 它们在翼上也有传感器 其机翼上都是传感器,包括一些 感觉机翼形变的传感器 它们甚至可以用它们的翅膀分辨味道 苍蝇最复杂的传感器之一 是一种结构被称为笼头。 笼头其实是陀螺仪。 在飞行中,这些设备以约 200 赫兹振动着 可以使用它们来感受其身体的旋转 并启动非常非常快速的纠正动作。 但所有这些感官信息需要由一个大脑来处理 事实上,苍蝇有一个大脑 脑内神经元约 100,000个
Now several people at this conference have already suggested that fruit flies could serve neuroscience because they're a simple model of brain function. And the basic punchline of my talk is, I'd like to turn that over on its head. I don't think they're a simple model of anything. And I think that flies are a great model. They're a great model for flies. (Laughter)
现在在这个会议的一些人 已经提议果蝇可帮助神经科学 因为它们是大脑功能的简单模型 我基本的观点就是 我想关注在它的头上 我并不认为它们是一个什么简单的模型 我认为苍蝇是一个伟大的模型 它们是苍蝇的伟大的模型 (笑声)
And let's explore this notion of simplicity. So I think, unfortunately, a lot of neuroscientists, we're all somewhat narcissistic. When we think of brain, we of course imagine our own brain. But remember that this kind of brain, which is much, much smaller — instead of 100 billion neurons, it has 100,000 neurons — but this is the most common form of brain on the planet and has been for 400 million years. And is it fair to say that it's simple? Well, it's simple in the sense that it has fewer neurons, but is that a fair metric? And I would propose it's not a fair metric. So let's sort of think about this. I think we have to compare -- (Laughter) — we have to compare the size of the brain with what the brain can do. So I propose we have a Trump number, and the Trump number is the ratio of this man's behavioral repertoire to the number of neurons in his brain. We'll calculate the Trump number for the fruit fly. Now, how many people here think the Trump number is higher for the fruit fly?
并让我们研究一下这种简单性 所以我认为,不幸的是,大量的神经学家 我们都有些自恋 当我们想到大脑时,我们当然想到的是我们自己的大脑 但请记住到这种大脑 这是小的很多的 没有 1000 个亿神经元,它有 100,000 个神经元 — — 但这是大脑在这个星球上最常见的形式 它存在了4 亿年 这可以说它很简单吗? 在某种意义上说这是比较简单的,因为它有较少的神经元 但是这是一个公平的指标吗? 我不觉得它是一个公平的指标 现在,让我们随便想想。我认为我们必须进行比较 (笑声) 我们要比较下大脑的大小 比较下大脑可以做什么 所以我建议我们用一个Trump号 Trump号是这个人的比例 由他的行为除以他大脑中神经元的数目得出 我们会计算出实蝇的Trump号 现在,在这里有多少人觉得Trump号 比实蝇的要高?
(Applause)
(掌声)
It's a very smart, smart audience. Yes, the inequality goes in this direction, or I would posit it.
观众们都很聪明 不平等是朝着这个方向走的,或者让我推断下
Now I realize that it is a little bit absurd to compare the behavioral repertoire of a human to a fly. But let's take another animal just as an example. Here's a mouse. A mouse has about 1,000 times as many neurons as a fly. I used to study mice. When I studied mice, I used to talk really slowly. And then something happened when I started to work on flies. (Laughter) And I think if you compare the natural history of flies and mice, it's really comparable. They have to forage for food. They have to engage in courtship. They have sex. They hide from predators. They do a lot of the similar things. But I would argue that flies do more. So for example, I'm going to show you a sequence, and I have to say, some of my funding comes from the military, so I'm showing this classified sequence and you cannot discuss it outside of this room. Okay? So I want you to look at the payload at the tail of the fruit fly. Watch it very closely, and you'll see why my six-year-old son now wants to be a neuroscientist. Wait for it. Pshhew. So at least you'll admit that if fruit flies are not as clever as mice, they're at least as clever as pigeons. (Laughter)
现在认识到它是有点荒谬 要比较人和苍蝇的行为 但让我们来看另一种动物,只是作为一个例子。这是一只老鼠 老鼠比苍蝇有约 1,000 倍多的神经元 我以前研究老鼠。当我研究老鼠的时候 我说话真的很慢 然后当我开始研究苍蝇的时候发生了一些状况 (笑声) 我觉得如果你比较苍蝇和老鼠的自然史 它是可比的。它们得去觅食 它们不得不求爱 它们要发生性关系。它们要躲避捕食者 它们做了很多类似的事情 但我想说苍蝇做更多 例如,我要向您展示一个影片 我不得不说,我的一些资金来自军方 因此,我将展示这个机密影片 你不能在外面讨论这个。好吗? 我想让你你看这个载荷 在果蝇的尾巴上 仔细看好了 你将看到为什么我的六岁儿子 现在想要一个神经学家 等待下 噗噗 所以至少你得承认,如果果蝇灭有老鼠聪明 它们至少和鸽子一样聪明。(笑声)
Now, I want to get across that it's not just a matter of numbers but also the challenge for a fly to compute everything its brain has to compute with such tiny neurons. So this is a beautiful image of a visual interneuron from a mouse that came from Jeff Lichtman's lab, and you can see the wonderful images of brains that he showed in his talk. But up in the corner, in the right corner, you'll see, at the same scale, a visual interneuron from a fly. And I'll expand this up. And it's a beautifully complex neuron. It's just very, very tiny, and there's lots of biophysical challenges with trying to compute information with tiny, tiny neurons.
现在,我想要传达的并不只是数字 而且是苍蝇面临的计算上的挑战 一切都得靠它的大脑,而却只有很少的的神经元 这就是老鼠的中间神经元的美丽图片 那是来自Jeff Lichtman的实验室 你可以看到大脑的精彩画面 他在他的研究种展示过 但在右上角,你看 在相同的比例下,从苍蝇的中间神经元的图像 我就会放大这个图像 它是一个精美复杂的神经元 它非常非常的小,尝试用这些极为微小的神经元来计算 充满了大量的生物物理挑战
How small can neurons get? Well, look at this interesting insect. It looks sort of like a fly. It has wings, it has eyes, it has antennae, its legs, complicated life history, it's a parasite, it has to fly around and find caterpillars to parasatize, but not only is its brain the size of a salt grain, which is comparable for a fruit fly, it is the size of a salt grain. So here's some other organisms at the similar scale. This animal is the size of a paramecium and an amoeba, and it has a brain of 7,000 neurons that's so small -- you know these things called cell bodies you've been hearing about, where the nucleus of the neuron is? This animal gets rid of them because they take up too much space. So this is a session on frontiers in neuroscience. I would posit that one frontier in neuroscience is to figure out how the brain of that thing works.
神经元能有多小?那么,来看看这个有趣的昆虫 它看起来像一只苍蝇。它有翅膀,眼睛 它有天线,双腿,复杂的生活史, 它是一种寄生虫,它得在周围飞,找毛毛虫 然后在上面寄生, 不仅仅它的大脑只有盐粒大小 跟果蝇相当 它只有一盐粒的大小 这里有类似规模的生物组织 这个动物跟草履虫和变形虫中大小相当 它有一个有7,000 个神经元的大脑,是太小了 你应该知道这些叫做细胞体的东西 神经元的核心在哪里? 这种动物去掉了它们,因为它们占用太多空间 这是一个神经科学的前沿的会议 我会认为这一神经科学前沿的研究是要找出大脑是如何工作的
But let's think about this. How can you make a small number of neurons do a lot? And I think, from an engineering perspective, you think of multiplexing. You can take a hardware and have that hardware do different things at different times, or have different parts of the hardware doing different things. And these are the two concepts I'd like to explore. And they're not concepts that I've come up with, but concepts that have been proposed by others in the past.
但让我们想一想。怎样可以使少量的神经元能做很多事情? 我认为,从工程的角度看 你会想到多路复用 您可以用硬件,并用该硬件 在不同的时间做不同的事情 或者用不同部分的硬件做不同的事情 我想要探讨这两个概念 这些都不是我自己想出来的概念 但在过去由其他人提出的概念
And one idea comes from lessons from chewing crabs. And I don't mean chewing the crabs. I grew up in Baltimore, and I chew crabs very, very well. But I'm talking about the crabs actually doing the chewing. Crab chewing is actually really fascinating. Crabs have this complicated structure under their carapace called the gastric mill that grinds their food in a variety of different ways. And here's an endoscopic movie of this structure. The amazing thing about this is that it's controlled by a really tiny set of neurons, about two dozen neurons that can produce a vast variety of different motor patterns, and the reason it can do this is that this little tiny ganglion in the crab is actually inundated by many, many neuromodulators. You heard about neuromodulators earlier. There are more neuromodulators that alter, that innervate this structure than actually neurons in the structure, and they're able to generate a complicated set of patterns. And this is the work by Eve Marder and her many colleagues who've been studying this fascinating system that show how a smaller cluster of neurons can do many, many, many things because of neuromodulation that can take place on a moment-by-moment basis. So this is basically multiplexing in time. Imagine a network of neurons with one neuromodulator. You select one set of cells to perform one sort of behavior, another neuromodulator, another set of cells, a different pattern, and you can imagine you could extrapolate to a very, very complicated system.
一个来自于咀嚼螃蟹的想法 我不是指咀嚼螃蟹 我在巴尔的摩长大,我非常会咀嚼螃蟹 但我说的是蟹咀的咀嚼行为 蟹咀的咀嚼行为其实真的令人着迷 螃蟹在甲壳下有复杂的结构 称为胃磨机 以各种不同方式在磨它们的食物 这里是用内镜拍的电影 令人惊异的是它受控于 由约有 20 多个神经元很小的神经元集 可产生多种不同的运动模式 它可以这样做的原因是,这个小小的神经节 实际上螃蟹密布着许多的神经调质 你早前听说过神经调质 有更多的神经调质 实际上比神经元在这个结构上分布得更多 它们能够生成一组复杂的模式 这是Eve Marder和她的许多同事的工作成果 他们一直在研究这个有趣的系统 这展示了神经元小群集怎样 可以做很多、 很多、 很多的事情 因为神经调节能时刻进行 所以这基本上复用的时间 想象一个神经元与一个神经调质构成的网络 你选择一组细胞来执行一种行为 另一个神经调质,另一组细胞 不同的模式,你可以想象 你可以推出一个非常、 非常复杂的系统
Is there any evidence that flies do this? Well, for many years in my laboratory and other laboratories around the world, we've been studying fly behaviors in little flight simulators. You can tether a fly to a little stick. You can measure the aerodynamic forces it's creating. You can let the fly play a little video game by letting it fly around in a visual display. So let me show you a little tiny sequence of this. Here's a fly and a large infrared view of the fly in the flight simulator, and this is a game the flies love to play. You allow them to steer towards the little stripe, and they'll just steer towards that stripe forever. It's part of their visual guidance system. But very, very recently, it's been possible to modify these sorts of behavioral arenas for physiologies. So this is the preparation that one of my former post-docs, Gaby Maimon, who's now at Rockefeller, developed, and it's basically a flight simulator but under conditions where you actually can stick an electrode in the brain of the fly and record from a genetically identified neuron in the fly's brain. And this is what one of these experiments looks like. It was a sequence taken from another post-doc in the lab, Bettina Schnell. The green trace at the bottom is the membrane potential of a neuron in the fly's brain, and you'll see the fly start to fly, and the fly is actually controlling the rotation of that visual pattern itself by its own wing motion, and you can see this visual interneuron respond to the pattern of wing motion as the fly flies. So for the first time we've actually been able to record from neurons in the fly's brain while the fly is performing sophisticated behaviors such as flight. And one of the lessons we've been learning is that the physiology of cells that we've been studying for many years in quiescent flies is not the same as the physiology of those cells when the flies actually engage in active behaviors like flying and walking and so forth. And why is the physiology different? Well it turns out it's these neuromodulators, just like the neuromodulators in that little tiny ganglion in the crabs. So here's a picture of the octopamine system. Octopamine is a neuromodulator that seems to play an important role in flight and other behaviors. But this is just one of many neuromodulators that's in the fly's brain. So I really think that, as we learn more, it's going to turn out that the whole fly brain is just like a large version of this stomatogastric ganglion, and that's one of the reasons why it can do so much with so few neurons.
是否有任何证据表明苍蝇这样做吗? 在我的实验室和其他世界各地的实验室 我们就一直在小飞行模拟器中研究苍蝇的行为 你可以把苍蝇系在一个小棒上 你可以测量它产生的空气动力 你可以让玩苍蝇玩一个小视频游戏 让它在显示器周围飞 我让你们看看一个小片段 这是一只苍蝇 和一个苍蝇飞行模拟器的大型红外图像 这是苍蝇喜欢玩的游戏 让它们导向到这个小条纹 它们会永远引向该带区 这是它的视觉导航系统的一部分 但非常,非常的最近 有可能为生理学而改变这种行为研究场所 这些准备,是由我之前一个博士后 叫Gaby Maimon开放的,他现在在洛克菲勒 这基本上是一种飞行模拟器 但你可以把电极插在 苍蝇的脑内 通过苍蝇大脑中用基因标示过的神经元做记录 这是这些实验的样子 它是从一个博士后实验室中拍摄的 叫Bettina Schenell 在底部的绿色踪迹是膜电位 来自苍蝇脑内的神经元 你将看到苍蝇开始飞翔,它其实是 自己控制着这种视觉模式的旋转 由其自身翼的运动 你可以看到这个视觉神经 在苍蝇飞行中对翼的运动做出的反应 我们实际上第一次能够记录 通过苍蝇的脑内神经元 而且这个苍蝇还在执行复杂的行为,如飞行。 我们一直在学习的经验教训之一 就是我们一直在研究的细胞的生理学 多年来在静止的苍蝇上 与这些细胞生理学并不相同的是 这是在当苍蝇处于运动状态下 比较飞行中和行走中等等。 为什么生理学上不同呢? 事实是这些神经调质 就像这小螃蟹的神经节调质 这里是章鱼胺系统的图片 章鱼胺上,神经调质 似乎在飞行和其他行为具有重要的作用 但这只是许多调质 这是在苍蝇的大脑中 所以我真的认为,当我们了解的更多 结果将是,整个苍蝇的大脑 就像这胃肠神经节的大版本 这就是为什么它可以做这么多事情却只有这么少的神经元的原因之一
Now, another idea, another way of multiplexing is multiplexing in space, having different parts of a neuron do different things at the same time. So here's two sort of canonical neurons from a vertebrate and an invertebrate, a human pyramidal neuron from Ramon y Cajal, and another cell to the right, a non-spiking interneuron, and this is the work of Alan Watson and Malcolm Burrows many years ago, and Malcolm Burrows came up with a pretty interesting idea based on the fact that this neuron from a locust does not fire action potentials. It's a non-spiking cell. So a typical cell, like the neurons in our brain, has a region called the dendrites that receives input, and that input sums together and will produce action potentials that run down the axon and then activate all the output regions of the neuron. But non-spiking neurons are actually quite complicated because they can have input synapses and output synapses all interdigitated, and there's no single action potential that drives all the outputs at the same time. So there's a possibility that you have computational compartments that allow the different parts of the neuron to do different things at the same time.
现在,另一个想法,另一种方式的多路复用 是空间多路复用 用神经元的不同部分 在同一时间做不同的事情 所以这里是典型的神经元的两个类型 从脊椎动物和无脊椎动物, Ramon Y Cajal(拉孟伊卡哈)的一个人类锥体神经元 和另一个右侧的细胞,非尖状的中间神经元 这是很多年前,Alan Waston和Malcolm Burrows的工作成果 Malcolm Burrows想出了一个很有趣的想法 基于一个事实,就是蝗虫的神经元 不会触发动作电位 它是一个非尖状的细胞 所以一个典型的细胞,像我们的大脑中的神经元 具有称为树突的区域来接收输入 并把输入累加在一起 并将产生动作电位 跑到轴突下,然后激活 所有输出区域的神经元 但是非尖状神经元其实相当复杂 因为它们有神经输突触入和输出突触 都是整合好的,没有单一的动作电位 在同一时间驱动所有输出 所以有可能有个计算单元 使得神经元的不同部分 在同一时间做不同的事情
So these basic concepts of multitasking in time and multitasking in space, I think these are things that are true in our brains as well, but I think the insects are the true masters of this. So I hope you think of insects a little bit differently next time, and as I say up here, please think before you swat.
这些是多任务处理的基本概念 在时间和空间,在多任务处理 我认为这些是在我们的大脑里面是一样的 但我认为昆虫是真正掌握要领的 因此,我希望下次你会觉得昆虫有点不同 而正如我在这里所说,请在拍死它们之前再三想想
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