New York scientists unveil robo-rat

By STEVE CONNOR

The age of the robotic rodent is upon us. A study has shown the movements of a live rat can be controlled by using a laptop computer, a radio and a set of microelectrodes implanted into the animal's brain.

"Ratbot", as the creature has been named, could one day be used to rescue earthquake victims buried under rubble, seek out land mines or even, with the help of miniature video cameras, spy inside secret installations.

Scientists used brain implants and tiny radio "backpacks" to guide five rats through a complex maze, composed of ladders, steps, hoops and ramps, from a distance of more than 500 yards.

Human operators were able to steer the Ratbots through the obstacle course as if they were guiding intelligent robots, said Sanjiv Talwar, a researcher at the State University of New York, who helped to run the study, published in the journal Nature.

"One can think of the guided rat as a very good robot platform capable of traversing terrain that modern robots are unable to do," Dr Talwar said yesterday.

The experiment involved exploiting the principle that an animal can be trained to do tasks by stimulating "reward" regions of the brain that normally respond to food, drink and sex.

Professor Patrick Bateson, an expert on animal behaviour at Cambridge University, said: "It's been known for a long time that animals will work like anything to get these rewards."

In conventional animal training, a morsel of food can be used as a reward "re- inforcement". In laboratory tests going back 40 years scientists have shown that direct electrical stimulation of the brain's pleasure centres is just as good or even better.

In this latest experiment, microelectrodes implanted directly into the reward centre of the rat's brain – a region called the medial forebrain bundle – were stimulated each time the rat made a move in the "correct" direction.

At the same time, the scientists implanted another set of electrodes into the brain regions receiving nerve impulses from the right and left set of whiskers. The rats were trained to move to each side depending on which set of whiskers was stimulated. If they did it correctly they were given a "reward" to the medial forebrain bundle.

The rats also quickly learnt to associate the stimulation of their brains' reward centres with simply walking forwards, even if this involved climbing or descending ladders or steps, or moving into the centre of a brightly lit room – something that most rats would avoid.

Dr Talwar said, however, that there were clear limits to what each rat could be made to do. "The rats worked within their instincts. They appeared to finely calibrate their awareness of a difficult obstacle versus the pleasure they would receive if they overcame it," he said.

Nevertheless, the rats were easily guided through pipes and across elevated runways and ledges, and could be instructed to climb, or jump from, any surface with a good foothold, such as a tree, the scientists write in Nature.

"We were also 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 areas," they say.

John Chapin, the leader of the research team and professor of physiology and pharmacology at the State University of New York, said that the rats could be made to "search" for an hour without showing any signs of getting tired or bored. "A search-and-rescue dog costs $60,000 [£43,000] to maintain and you cannot use them in very tight spaces," Dr Chapin said. "Nor could you use a dog to discover land mines, since the weight of the animal would detonate the explosive. A rat, however, being small and light, could sit on the mine without exploding it.

"In addition, rats are more mobile than mechanical robots, which are often stymied by obstacles such as fences, rocks and debris. While robots would be useful in environments where a living thing could not survive, such as where there are fires or poisonous gases, the rat has rather sophisticated navigational skills developed over 200 million years of evolution. It makes sense to make good use of the animal's abilities," Dr Chapin said.

The Chapin team published work in 1999 showing that rats could be trained to operate a robotic arm using the power of thought alone.

In this experiment, each rat had microelectrodes implanted into the region of the brain that controlled the movement of its limbs. The animals were then trained to operate a lever with a foot to release food.

After a period of time, the operation of the lever was taken over by a mechanical arm and each rat quickly learnt that the mere thought of using its limbs to operate the lever still resulted in access to the food.

Another set of experiments a year later on monkeys showed that the same principle could be applied to primates. In this test the scientists even managed to get the monkeys to use mind control to operate robotic arms over the internet some 600 miles away.

One aim of the research is to develop a means whereby severely paralysed patients could control the movements of robot arms and other devices by the power of thought alone.

According to Dr Talwar, the latest work on Ratbot could lead to a way of controlling a robotic arm with the extra help of the sense of touch.

"The larger idea behind the study was to continue our research in neurorobotics," Dr Talwar said. "We wanted to get an idea about how effectively can animals sense brain- stimulation cues. This would enable us to evaluate the feasibility of a 'sensory' prosthesis, which could enable paralysed patients to experience sensations such as touch and so be able to better control an artificial limb through a suitable brain-machine interface," he said.

If this research continues to advance, the age of Ratbot could be a prelude to the day when paralysed humans could operate artificial limbs, just like the half-human cyborgs of science fiction.

- INDEPENDENT