Electrodes on the brain of a paralyzed man allowed him to move a robot arm to touch a friend's hand for the first time in seven years, researchers said. Tim Hemmes, 30, who sustained a spinal cord injury in a motorcycle accident seven years ago that left him unable to move his body below the shoulders, was able to use brain-computer interface technology to control movement of a computer cursor and later a robot arm, researchers at the University of Pittsburgh School of Medicine reported Friday. Hemmes' thoughts were interpreted by computer algorithms and translated into intended movement, they said. "When Tim reached out to high-five me with the robotic arm, we knew this technology had the potential to help people who cannot move their own arms achieve greater independence," lead researcher Wei Wang said. In implantation surgery, a postage stamp-size grid of 28 recording electrodes was placed on the surface of Hemmes' brain region that controlled right arm and hand movement. Wires from the device exited under the skin of his chest where they could be connected to computer cables as necessary. Hemmes slowly learned to use his thoughts to guide the up and down motion of a ball on a computer screen. "During the learning process, the computer helped Tim hit his target smoothly by restricting how far off course the ball could wander," Wang said. "We gradually took off the 'training wheels,' as we called it, and he was soon doing the tasks by himself with 100 percent brain control." The robot arm Hemmes eventually learned to control was developed by Johns Hopkins University's Applied Physics Laboratory.