Fayette man's rapid control of robotic arm at Pitt lab detailed in 'Science'
May 20—Having the sensation of touch makes quite a difference for Nathan Copeland, even if it's a simulation.
The 35-year-old man from Dunbar, Fayette County, lost the sensation and most of the motion in his limbs at 18 when he broke his neck in a car crash.
Since 2014, he's been participating in a study at the University of Pittsburgh Rehab Neural Engineering Labs, gaining increased dexterity while moving a robotic arm controlled by tiny electrode arrays implanted in his brain.
In a paper published Thursday in Science, a team of bioengineers at the lab detailed just how well Copeland can manipulate objects with the arm when he receives tactile sensory feedback from the artificial limb. The sensation is delivered through additional electrodes in his somatosensory cortex, a region of the brain that processes sensory information from the body.
When visual cues were supplemented with that artificial sense of touch, he cut in half the time he needed to grasp and transfer objects with the arm — from a median time of 20.9 second to 10.2 seconds.
"This is what we hoped would happen — but perhaps not to the degree that we observed," said Jennifer Collinger, co-senior author of the paper and associate professor in the Pitt Department of Physical Medicine and Rehabilitation. "He really improved his ability to pick up and grab objects.
"Sensory feedback from limbs and hands is hugely important for doing normal things in our daily lives, and when that feedback is lacking, people's performance is impaired."
As part of the study, Copeland manipulated objects such as tubes of various sizes, spheres, cups and cylinders — transferring them from a table to a raised platform.
"Even though the sensation isn't 'natural' — it feels like pressure and gentle tingle — that never bothered me," he said. "There wasn't really any point where I felt like stimulation was something I had to get used to. Doing the task while receiving the stimulation just went together like PB&J."
As Copeland's work with the Pitt team progressed, an increased number of electrodes was used to simulate sensations in the index, ring and pinky fingers of his right hand.
The first person in the world to have the electrode arrays implanted, Copeland makes the trip from his home to the lab three days each week to continue with the study. Pitt is working with one additional subject, while a third person is undergoing tests at the University of Chicago, Collinger said.
As the study moves forward, the Pitt team is assessing Copeland's ability to control the pressure he applies while grasping objects with the robotic arm, with the idea of replicating more natural manual tasks.
Exercises include picking up a virtual egg. "We're working mostly with virtual things right now," Collinger said. "We do have a 3-D-printed tube that will break if you exceed a particular force."
She said an eventual goal is to adapt the robotic system for home use by those who have lost use of their arms, perhaps combining it with other technology that seeks to restore function by stimulating the muscles or nerves in a subject's arm.
Pitt associate professor Robert Gaunt is the co-senior author of the paper. Additional authors include Sharlene Flesher, Jeffrey Weiss, Christopher Hughes, Angelica Herrera and Michael Boninger, M.D., all of Pitt; John Downey, of the University of Chicago; and Elizabeth Tyler-Kabara, M.D., of the University of Texas at Austin.
The work was supported by the Defense Advanced Research Projects Agency and Space and Naval Warfare Systems Center Pacific under the Revolutionizing Prosthetics program.
Jeff Himler is a Tribune-Review staff writer. You can contact Jeff at 724-836-6622, jhimler@triblive.com or via Twitter .
