London, Sep 2 (IANS): Bats do not use sight to navigate when flying, but when they fly close to an object, the number of active neurons in certain parts of their brain increase, warning them of an impending collision, says a study.

Adapted to lead a life without light, bats emit echolocation sounds and use the delay between the reflected echoes to measure distance to obstacles or prey.

In their brains, they have a spatial map representing different echo delays and this map dynamically adapts to external factors, the findings of the study showed.

When a bat flies in too close to an object, the number of activated neurons in its brain increases.

As a result, the object appears disproportionately larger on the bat's brain map than objects at a safe distance, as if it were magnified.

"The map is similar to the navigation systems used in cars in that it shows bats the terrain in which they are moving," said study director Uwe Firzlaff from Technische Universitat Munchen (TUM) in Germany.

"The major difference, however, is that the bats' inbuilt system warns them of an impending collision by enhancing neuronal signals for objects that are in close proximity," Firzlaff added.

Bats constantly adapt their flight manoeuvers to their surroundings to avoid collisions with buildings, trees or other animals.

"Our research has led us to conclude that bats display much more spatial information on their acoustic maps than just echo reflection," Firzlaff noted.

The findings appeared in the journal Nature Communications.