They were also able to train the rats to sniff out the explosives TNT and RDX- key after terrorist attacks that may leave buildings harbouring unexploded bombs. "There are two neural events that we believe are hallmarks of the 'aha!' moment for the rat," says Linda Hermer-Vazquez. These are high-frequency activity in one subset of neurons, and decreased activity in two other areas, she says. Signals from the rat's brain will be relayed to a radio transmitter pack strapped to the animal's back, which Chapin is developing. Rescuers will be able to follow the rat's position by tracking these signals. They are also developing software that will recognise the "aha!" moment when the rat has found its target, so rescuers will know where to start digging. The team hope to create a working system within nine months. Other teams looking at ways to seek people trapped under debris have designed wheeled, tracked or even snake-like robots that can slither into wrecked buildings (New Scientist, 10 November 2001, p 22).
But rats have several advantages. "Artificial noses don't work well when there are other smells around," says Christiane Linster, an olfaction expert at Cornell University in New York. "Rats are good at that." Rats are also adept at navigating over unexpected obstacles, and of course they don't need an electricity supply. Rescue teams welcome the idea. "It would be absolutely fantastic," says Julie Ryan of International Rescue Corps in Scotland, which flies rescuers to disaster zones around the world. "A rat could get in voids and spaces we couldn't get to. And a rat would try to get out if it didn't feel safe."
Written by EMILY SINGER, BOSTON
This article appears in New Scientist issue: 25 September 2004
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