Then a member of the scientific team, using a laptop computer, remotely stimulated the microprocessor to send an electrical signal through one cue wire or the other. The rat "felt" a touch to the corresponding set of whiskers, as though it had come in contact with an obstacle.
If the rat responded by turning in the desired direction, the controller encouraged the animal with a brief electrical pulse to its brain's reward center. The rat would feel a sensation of pleasure.
This pattern of stimulus and response is parallel to the way that a shepherd might train his sheepdog, Talwar said, "except the rat will not work for love." Instead of offering an encouraging scratch behind the ears, Talwar's technique creates a world of "virtual cue and virtual reward" in which the rat learns to respond to the remote orders rather than rely on its own instincts, he said. The animals demonstrated an impressive ability to learn and remember how to interpret remote commands. It took no more than ten sessions to train the five animals the researchers used.
After training, some of the rats were retired for up to half a year before once again being outfitted with microprocessors and wires. They still responded readily to orders from the laptop.
Once the rats were trained, the scientists piloted them through a gauntlet of tests.
"We were able to guide rats in systematically exploring large, collapsed piles of concrete rubble, and to direct them through environments that they would normally avoid, such as brightly lit, open arenas," the researchers wrote in the paper in which they presented their work, which appeared in the May 2 issue of the journal Nature.
The development of the robo-rat grew out of earlier work that Talwar and his colleagues had done on brain-machine interfaces. One project had enabled a rat to move a robotic arm merely by thinking about it. Talwar hopes that this technology can be applied to help disabled people manipulate machines that can serve them in the place of lost or paralyzed limbs.
After September 11, Talwar said, he and his colleagues saw that there might be other useful applications for their technology.
Talwar acknowledged that some peopleincluding himselffeel somewhat uncomfortable with the notion that animals can be remotely controlled. "The idea sounds a little creepy," he admitted.
Nevertheless, he noted, the rats don't suffer because they receive only "reward" neural feedback, never negative stimuli. And, Talwar said, "there is no cruelty" involved in operating robo-rats because the animals are never intentionally killed or harmed.
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