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The research gives a glimpse of the possibilities for training animals by sending cues and rewards directly to their brains, says Sanjiv Talwar of the State University of New York Downstate Medical Center. In the May 2 Nature, he and his colleagues predict their accomplishment could inspire novel approaches to land mine detection or search-and-rescue missions. The project grew out of research to develop new types of prostheses for paralyzed people that will use electric impulses sent directly to and from the brain. In 1999, coauthor John Chapin and his colleagues at the medical center demonstrated that signals from a rat's brain could move a robotic arm. Talwar says that the January 2001 earthquake in Bhuj, India, and the September terrorist attacks inspired the researchers to use elements of their prosthesis work to create remote-control rats that might eventually navigate in collapsed buildings. The Defense Advanced Research Projects Agency funds the research. The team fitted five rats with electrodes in their brains and backpacks containing electronics. For cues, the researchers sent electric signals to brain regions that process impulses from whiskers. For rewards, the researchers stimulated a pleasure center known as the medial forebrain bundle. The researchers put each rat in a maze and, as the animal approached a turning point, stimulated its brain to mimic a whisker touch on one side. When a rat turned in the direction of the virtual touch, the researchers buzzed the brain's pleasure center. These signals to the pleasure center seemed to spur a rat to go forward, even when the path required climbing steps or hopping off a ledge. "He learns, 'If I keep moving, I feel these bursts of transcendental happiness,'" Talwar says. "The rats figure it out in 5 or 10 minutes." The researchers explored the capabilities of this system by steering the rats over a jumble of concrete, across a brightly lit arena that rats would normally avoid, and even up a tree. The rats move far more nimbly than robots can, says Talwar. The team envisions rescue animals sending back signals that indicate they've reached their goal. Robin Murphy, who develops search-and-rescue robots at the University of South Florida in Tampa, says that the wired rat may be useful in experiments, but "it does not appear to be appropriate for search and rescue." Murphy cautions that many practical questions remain, such as how people could guide a rat when it's out of sight and whether virtual rewards can keep it on task amidst distractions.