Insects can see more clearly than previously thought

Researchers used their updated understanding of the mechanics of compound eyes to build a model of a fruit fly's visual system.
By Brooks Hays  |  Sept. 5, 2017 at 11:38 AM
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Sept. 5 (UPI) -- New research suggests insects can see the world at a much finer resolution than previously thought.

Until now, scientists assumed the compound eyes -- thousands of tiny lensed eyes -- deployed by most insects offered only a low-resolution composite image of their surroundings. In contrast, human eyes feature a large, single lens and a large, densely packed photoreceptor capable of keeping objects in focus at varying distances and producing high-resolution images.

When a team of researchers from England, Portugal and China probed the inner workings of the insect eye, or eyes, they found the optical setup is capable of surprisingly high-resolution approximations of the outside world.

Unlike the human eye, insect eyes can't change shape to keep objects in focus and yield high resolutions. But it turns out insects have a different technique for generating high-res images.

Behind each lens in a compound eye are photoreceptor cells. These cells move in and out of focus as they sample the incoming light. These tiny light-sensors switch on and off too fast to be seen with the naked eye. To study the process, scientists had to design their own tiny microscope outfitted with a high-speed camera.

The team of scientists, led by researchers at the University of Sheffield, found insects can generate high-resolution images by combining photoreceptor twitching with their natural rapid eye and head movements, known as saccadic bursts.

Researchers used their updated understanding of the mechanics of compound eyes to build a model of a fruit fly's visual system. Their modeled produced surprisingly high-definition images of the surrounding world.

"It has long been known that fast visual adaptation results in the world around us fading from perception unless we move our eyes to cancel this effect," Sheffield neuroscientist Mikko Juusola said in a news release. "On the other hand, fast eye movements should blur vision which is why it has remained an enigma how photoreceptors work with eye movements to see the world clearly."

"Our results show that by adapting the way photoreceptor cells sample light information to saccadic eye movements and gaze fixations, evolution works towards optimizing the visual perception of animals," Juusola said.

Researchers detailed their analysis of insect eyes in a new paper published this week in the journal eLife.

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