为什么你总拍不到苍蝇？看看绿头苍蝇，那是真正的视觉大师。科学家给苍蝇系上飞行模拟器来研究其视觉控制飞行的秘密。

你是否也有过这样的困惑：一只脑袋这么小的昆虫为什么几乎每次都能摆脱你的围捕？

为了探明普通绿头苍蝇（也叫青蝇）如何以比人类快四倍多的速度完成对视觉图像的处理，研究人员为这种小昆虫制作了一个飞行模拟器。马克斯·普朗克神经生物学研究所的生物学家在这些昆虫固定上一个适合苍蝇尺寸的背带，并把电极固定在其脑部后，再把它们放到一个半环形的LED（发光二极管）屏幕前，屏幕能呈现出各种各样的运动模式。

当苍蝇对飞在其周围的虚拟物体作出反应时，科学家利用一个荧光显微镜来观察苍蝇大脑的成像过程。人类每秒最多可辨别出25个离散的图像，相比之下，苍蝇则是视觉大师：它们每秒能甄别出多达100幅的独立图像。而且能以闪电般的反应速度改变其飞行方向。

德国科学家希望，对昆虫视觉的研究成果会有助于创造出飞行技术更高超的机器人。不过他们不是唯一利用飞行模拟器研究苍蝇的人——加利福尼亚理工学院迈克尔·狄金森领导的研究小组已经利用一个名为“视觉控制飞行器”（Fly-O-Vision）的类似装置来了解果蝇的肌肉协调和视觉处理。

去年，狄金森在一份新闻稿中写道：“工程师们希望能够创造出一些构造简单却具有复杂行为方式的东西，比如电网或机器人。查明简单物体如何获得复杂行为能力的最好的方法之一，是研究生物有机体。这就像生物系统模型101：先研究一种容易研究的动物，然后再以此作出推断。”

Have you ever wondered how an insect with such a tiny brain can thwart your attempts to catch it nearly every time? Apparently scientists do, too.

To find out how the common bluebottle manages to process visual images more than four times faster than humans, researchers have built the bug a flight simulator. After immobilising each insect with a fly-sized harness and attaching electrodes to its brain, biologists from the Max Planck Institute for Neurobiology placed flies in front of a semicircular LED screen displaying various moving patterns.

As the fly responded to virtual objects flying around it, the scientists used a fluorescent microscope to watch how its brain processed the images. Compared to people, who can distinguish a maximum of 25 discrete images per second, flies are visual virtuosos: they can sense up to 100 separate images per second and respond fast enough to change their flight direction.

The German scientists hope what they discover about insect vision will help build better flying robots. And they're not the only ones studying flies in a flight simulator - a group led by Michael Dickinson at the California Institute of Technology has used a similar setup, called Fly-O-Vision, to learn about muscle coordination and visual processing in fruit flies.

"Engineers would like to be able to build simple things that behave in complex ways, like a power grid or a robot, and one of the best ways to figure out how to get complex behaviour from simple things is by studying biological organisms," wrote Dickinson in a press release last year. "It's Model Biological Systems 101: study an animal that's easy to study, and then extrapolate."

PHOTO CREDIT: MPI Neurobiologie