Nerve cells help flies respond quickly to obstacles while flying

Washington, July 22 : Researchers at Imperial College London have discovered that two key sets of nerve cells in a fly's brain enable it's gaze to stay stable during complex aerial manoeuvres, and to respond quickly to obstacles in its flight path.

Describing their study in the journal PLoS Biology, the researchers said their findings might be helpful in understanding how nervous systems operate as well as in improving scientists' knowledge of more complex animals.

The researchers also believe that their findings might be used to improve technical control systems in autonomous air vehicles - robots that stay stable in the air without crashing, and without any need for remote control.

They say that flies need to keep their gaze steady during their slightly more complicated aerial manoeuvres, which helps them process visual information about their surrounding environment more efficiently and modify their movements accordingly.

According to them, their latest study shows that the way in which two populations of nerve cells (neurons) communicate with each other is the key to this process.

The researchers say that the lobula plate tangential cells receive input from the eyes, and this generates small electrical signals that inform the fly about how it is turning and moving during its aerial stunts.

The signals pass on to a second set of neurons that connect to the neck muscles, and stabilise the fly's head and thus its line of sight.

Dr. Holger Krapp, a bioengineer who led the study, said that the pathway from visual signal to head movement is ingeniously designed: it uses information from both eyes, is direct, and does not require heavy computing power.

"Anyone who has watched one fly chasing another at incredibly high speed, without crashing or bumping into anything, can appreciate the high-end flight performance of these animals," he said.

"They manage even though they see the world in poor definition: their version of the world is like a heavily pixelated photo compared with human vision. However, they do have one major advantage. They can update and process visual information more than ten times faster than humans, which is vital for an insect that relies on fast sensory feedback to maintain its agility," he said.

Dr Krapp added: "Keeping the head level and gaze steady is a fundamental task for all animals that rely on vision to help control their movements. Understanding the underlying principles in simple model systems like flies could give us useful leads on how more complex creatures achieve similar tasks."

ANI