Washington: Scientists have identified the mechanism by which animals are propelled toward food, and compare it to "a tiny, specialised computer".

The mechanism works for simple animals such as roundworms, propelling them towards food, as well as humans hungrily hunting for a pizza.

Oregon University researchers have documented how two related, closely placed chemosensory neurons acting jointly regulate such behaviour in roundworms.

The left neuron controls an "on" switch, while the opposing right one an "off" switch. These sister neurons are placed like the two nostrils or two eyes of mammals. Together these neurons are known as antagonistic sensory cues, or ASE.

"This 'computer' does some nice calculus, differentiating the rate of change of the strength of various tastes," said Shawn Lockery, who led the study. "The worm uses this information to find food and to avoid poisons."

Lockery and colleagues predicted the existence of a derivative-crunching mechanism in the Journal of Neuroscience in 1999 based on findings that nematodes change directions based on taste and smell.

"In effect, they have two nostrils or two tongues but they are so close together that it is really like having one nostril or one tongue, and yet they find their way around quite effectively," Lockery said.

To get there, Lockery and colleagues used new imaging and molecular tools, along with some genetic engineering of their worms.

Lockery said the discovery could help research aimed at treating people with problems involving taste and smell. IANS