WASHINGTON D.C. - While a higher percentage of U.S. soldiers are surviving their time in war thanks to life-saving technologies such as advanced body armor, many are returning home maimed and have had arms or legs amputated as a result of injuries.

A new research agenda set out by the Defense Advanced Research Projects Agency (DARPA) aims to restore some of the lost functionality for these soldiers by developing advanced prosthetics that look, feel, and act like the limbs they replace.

The ultimate goal would is limbs that would work well enough to play piano and live normal daily lives.

Speaking at the annual meeting for the American Association for the Advancement for Science here last week, Geoffrey Ling, a DARPA researcher, said the agency wants to begin by creating an advanced prosthetic arm, and that it plans to tackle this challenge from two fronts: by encouraging the development of computer interfaces that allow for the brain control of machines, and by developing new synthetic materials and portable energy sources that can be integrated into a life-like prosthetic.

Most current prosthetics utilize at best crude forms of sensory feedback and are dependent on muscle rather than neural control. They require extensive training and offer only limited functionality.

"Unless we have a paradigm shift towards neural control, we aren't going to get away from the hook," Ling said.

The agency has set high goals for its researchers and envisions an advanced prosthetic arm with specific properties. The device will need to have, at a minimum, the equivalent of 40 pounds of arm strength and 8 pounds of grip strength.

"We want our soldiers to be able to go back to doing the daily activities of daily life," Ling said.

DARPA hopes to have a working prototype that can partially respond to neural control by 2007. The ultimate goal, Ling said, is to have a prosthetic device that looks and feels like a real arm, that can respond to the whims and thoughts of its user, and that blends seamlessly with the body.

"We want our soldiers to be able to play the piano," Ling said. "Not chopsticks, but a classical piece, like Brahms."