Rats and Radio waves

Thu Sep 23 21:29:51 CDT 2004

    NewScientist.com

Rats' brain waves could find trapped people

19:00 22 September 04

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Rats equipped with radios that transmit their brainwaves could soon be 
helping to locate earthquake survivors buried in the wreckage of 
collapsed buildings.

Rats have an exquisitely sensitive sense of smell and can crawl just 
about anywhere. This combination makes them ideal candidates for 
sniffing out buried survivors. For that, the animals need to be taught 
to home in on people, and they must also signal their position to 
rescuers on the surface.

In a project funded by DARPA, the Pentagon's research arm, Linda and Ray 
Hermer-Vazquez of the University of Florida in Gainesville have worked 
out a way to achieve this.

  	Trained rats reach the places that sniffer dogs cannot 
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	Trained rats reach the places that sniffer dogs cannot

First the researchers identified the neural signals rats generate when 
they have found a scent that they are looking for. "When a dog is 
sniffing a bomb, he makes a unique movement that the handler 
recognises," says John Chapin, a neuroscientist at the State University 
of New York in Brooklyn who is collaborating on the project. "Instead of 
the rat making a conditioned response, we pick up the response 
immediately from the brain."

Pleasurable sensations

Each rat has electrodes implanted in three areas of the brain: the 
olfactory cortex, where the brain processes odour signals; the motor 
cortex, where the brain plans its next move; and the reward centre, 
which when stimulated gives the rat a pleasurable sensation.

The electrodes, each consisting of an array of up to 32 stainless steel 
wires 75 micrometres in diameter, are permanently implanted in the brain 
and can give accurate signals for up to nine months.

The researchers trained the rats to search for human odour by 
stimulating the reward centre when it found its target smell. Once the 
rats were trained, they were set to forage for the target smell, while 
electrodes recorded their neural activity patterns.

This allowed researchers to identify the brainwave patterns associated 
with finding that smell. 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.

High-frequency activity

"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 print edition, 10 November 2001).

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 do not 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 into areas 
and spaces we couldn't get to. And a rat would try to get out if it 
didn't feel safe."

Emily Singer

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