Researchers from the University of Pittsburgh and University of Pittsburgh Medical Center have demonstrated, for the first time, technology that allows a paralyzed patient to experience the sensation of touch through a neural interface connected to a robotic arm, according to a press release.
With funding from the Defense Advanced Research Projects Agency (DARPA) Revolutionizing Prosthetics program, the team developed a two-way communication system between the brain and the robotic arm. The communication system used outgoing signals for movement and inbound signals for sensation, creating the sensation of touch directly in the brain. The results are published in Science Translational Medicine.
“DARPA had previously demonstrated direct neural control of a robotic arm, and now we have completed the circuit, sending information from a robotic arm back to the brain,” Justin Sanchez, PhD, program manager for the Revolutionizing Prosthetics program and director of DARPA’s Biological Technologies Office, said in the release. “This new capability fundamentally changes the relationship between humans and machines.”
According the release, the study volunteer has quadriplegia below his upper chest that resulted from a 2004 car crash that broke his neck and injured his spinal cord. After agreeing to participate in the clinical trials, he underwent surgery that placed four microelectrode arrays in his brain — two in the motor cortex and two in the sensory cortex. The researchers then connected wires from those arrays to a robotic arm developed by the Applied Physics Laboratory at Johns Hopkins University.
The prosthetic arm contained torque sensors capable of detecting when pressure is applied to any of its fingers, according to the release. The arm was also able to convert those sensations into electrical signals that the wires can carry back to the arrays in the brain, giving precise patterns of stimulation to the sensory neurons.
In the first round of tests, the researchers gently touched each of the robotic fingers while the participant wore a blindfold. According to the release, he was able to report which finger was touched with nearly 100% accuracy.
“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 hand were near-natural.”
Flesher S. Sci Transl Med. 2016;doi: 10.1126/scitranslmed.aaf8083.
Disclosure: The researchers report no relevant financial disclosures.