A newly developed neural technology has allowed a person with paralysis from a spinal cord injury to “feel” physical sensations through a prosthetic hand directly connected to his brain and identify which fingers on the hand are being touched.
The technology is under development through the Defense Advanced Research Projects Agency’s (DARPA) Revolutionizing Prosthetics program and could allow people with paralysis or amputation to manipulate objects by sending signals from their brain to a robotic device and to sense what the devices are touching, according to a press release.
“We have completed the circuit,” Justin Sanchez, DPhil, MEng, DARPA program manager, said in the release. “Prosthetic limbs that can be controlled by thoughts are showing great promise, but without feedback from signals traveling back to the brain, it can be difficult to achieve the level of control needed to perform precise movements. 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.”
Researchers placed electrode arrays onto the patient’s sensory cortex and motor cortex — the parts of the brain that identify tactile sensations and that direct body movements, respectively — and ran wires from the motor cortex to the mechanical hand, which was developed by the Applied Physics Laboratory (APL) at Johns Hopkins University. The patient was then able to control the movement of the prosthesis with his thoughts.
Additional wires routed from the brain to the hand converts physical “sensations” into electrical signals, providing a sense of touch. In the first set of tests, researchers gently touched each of the prosthetic hand’s fingers while the patient wore a blindfold. The patient was able to report with almost 100% accuracy which finger was being touched.
“At one point, instead of pressing one finger, the team decided to press two without telling him,” Sanchez said. “He responded in jest asking whether somebody was trying to play a trick on him. That is when we knew that the feelings he was perceiving through the robotic hand were near-natural.”
Sanchez described the study’s initial findings at a recent DARPA technology forum. More information will be released pending review and acceptance for publication in a scientific journal.