Zombie Rats Train for Military MissionsRemote-controlled rats to sniff out explosives
# NewScientist.com news service
# Will Knight
An elite squad of real but remote-controlled rats could soon be scouring enemy bases and sniffing out explosives for the US military.
The rodents are directed using a series of brain implants, which can be operated wirelessly from a distance of several hundred metres. Now, for the first time, the researchers behind the project have demonstrated the ability to control the rodents' movements before activating their “sniffer dog” instincts.
John Chapin and colleagues at the State University of New York, US, say the rats could eventually sniff out hidden weapons or act as remote video sensors for military and police forces.
With colleagues from the University of Florida in Gainesville, US, they have previously shown that brain implants can be used to steer the rats over an assault course, or home in on a particular odour. But combining the two tricks is a significant step towards turning them into useful “robo-rodents”.
Whiskers and reward
"It's important to have them switch between behaviours," Chapin told New Scientist. "Obviously, there are a lot of very important potential applications.”
The rats are remotely controlled using electrodes inserted into the medial forebrain bundle (MFB), a part of their brain associated with reward, and the somatosensory cortical area, which is linked to the right and left whiskers.
Stimulating the whisker areas of the brain along with the forebrain reward region encourages the rats to move forwards or either left or right. Exposing the rats to a smell while stimulating the medial forebrain bundle causes them to act like miniature sniffer dogs, following an odour by instinct.
Recent experiments have now shown that these two behaviours are compatible and the rats can be directed to an area before being encouraged to sniff out a target.
Tracking chemical traces
The experiments show that rats trained through direct electrode stimulation of the brain are better at locating an object by smell than those trained using food. Remarkably, the rats remained highly motivated to seek out odours even after six weeks had passed since electrode training.
The rats’ olfactory talents are such that it should be possible to train them to locate explosives or drugs by the tiny chemical traces they emanate, Chapin says.
But, whereas sniffer dogs are trained to crouch down or make some other signal when they locate something, the researchers hope to use brain signals discover when a rat has reached its target, too. Previously they had hoped to monitor the olfactory regions of the brain, but Chapin says monitoring the limbic system within the brain - which shows when the rat thinks it is about to get a reward - is more effective.
The research, which is funded by the US Defense Advanced Research Projects Agency, will appear in a forthcoming edition of the journal Physiology and Behaviour.
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