Swiss scientists have discovered a kind of eye cells that, without taking the brain's help, can alert people to any objects drawing near.
Botond Roska and his colleagues at the Friedrich Miescher Institute for Biomedical Research in Basel believe that this ability may have evolved to speed escape from predators.
As to the significance of this finding, the researchers say that scientists have thus far known that the only cells that are sensitive to approaching objects exist in the brain.
While investigating mouse eye cells, the researchers noticed that one type behaved unusually in response to movement.
Upon further analysis, they observed that this one kind of retinal cell fired only when an object approached.
Based on that observation, the researchers came to the conclusion that people might have similar cells, which alert them to approaching objects faster than the brain cells do.
"It's an alarm system that's as close to the front end of the organism as possible. If you left it to the brain to respond, it might be too late," New Scientist magazine quoted Roska as saying.
He has revealed that his next step will be to find out how the approach-sensitive cells evoke a reaction in the brain.
Russell Foster, a neuroscientist at the University of Oxford, said: "This is exciting work. How the nerve cells of the visual system work out that an object is approaching represents a very old question in neuroscience."
A research article on this study has been published in the journal Nature Neuroscience.