One of the Defense Advanced Research Project Agency's (DARPA) out-there projects has borne fruit, with the agency announcing that it's partially restored a sense of touch to someone with a spinal cord injury.

The achievement, outlined here, followed on from a July announcement that DARPA had given a former US serviceman Glen Lehman a mind-controlled prosthetic limb.

In the latest work, an unnamed 28-year-old paralysed by a spinal cord injury more than ten years ago was given the prosthetic limb with a direct connection to his brain, meaning not only could he command the arm, but could “feel” sensations well enough to identify which finger was being touched.

Justin Sanchez, project manager in DARPA's Revolutionizing Prosthetics program, said the success means “We've completed the circuit”.

“By wiring a sense of touch from a mechanical hand directly into the brain, this work shows the potential for seamless bio-technological restoration of near-natural function”, Sanchez added.

For control, the robot arm is linked to the user's motor cortex, while (naturally enough) a connection to the sensory cortex provides the sense of touch.

The sensory connection is to torque sensors in the hand, which detect when pressure is applied to its fingers and creates electrical signals to the “arrays on the volunteer's brain”, DARPA said.

The researchers reckon the sensation the user gets is “nearly natural”, since even on the first tests, he was able to identify which finger was touched with “nearly 100 per cent accuracy”, and caught the researchers out when they tried to trick him by touching two fingers at once. ®