By Kristine Lister '18
While prosthetic limbs have enabled people all over the world to regain lost control of their extremities, new research has re-enabled the sense of touch for 28-year old Nathan Copeland. Twelve years ago, a car crash injured Copeland’s spinal cord and took away the control of his hands, including his sense of touch. Only a few months ago researchers at the University of Pittsburgh and the University of Pittsburgh Medical Center have given Copeland a mind-controlled robotic arm that enables him the sensation of touch.The research was led by Robert Gaunt, Ph.D., assistant professor of physical medicine and rehabilitation at the University of Pittsburgh, in correspondence with Sliman Bensmaia, Ph.D., associate professor of organismal biology and anatomy at the University of Chicago. The researchers developed a brain computer interface (BCI) that is connected to the robotic arm and transmits sensory feedback through microelectrode arrays that are implanted into the somatosensory cortex of the brain. This research was published in Science Translational Medicine on October 13th, 2016.This breakthrough incorporates years of research by Bensmaia on how the nervous system interprets sensory feedback. Bensmaia had identified patterns of neural activity that occurred when animals touched objects, and it was the goal of the researchers to recreate these signals using electricity. Before Copeland’s procedure, his brain activity was monitored using magnetoencephalography, which allowed the team “to see the parts of his brain that became active when he was watching videos of a hand being touched," Gaunt says. Next the researchers placed electrodes the size of buttons in the areas of Copeland’s brain that corresponded to stimulations of each finger. They let the brain heal and re-adjusted the electrodes several times before they could send the first pulse of electricity to Copeland’s brain. "When it finally happened, he just very calmly said, 'Yep, I felt it on my index finger,'" Gaunt recalls.When Copeland touches an object with his robotic hand, he can tell which finger is touching it and whether the object feels hard or soft. "It's a really weird sensation," Copeland, now 30, says in a video made shortly after he first tried the system. "Sometimes it feels, kind of, like electrical and sometimes it's more of a pressure." According to Bensmaia, as Copeland continues to use the robotic arm his brain will become more accustomed with the signals, leading to more integrated interactions with the world. Although the robotic arm can only sense pressure and hardness now, further research will go into enabling other capabilities such as temperature sensitivity.This research is critical in furthering the capabilities of prosthetic limbs. Without the sense of touch, one needs to see the objects they are interacting with to tell how much force should be applied to manipulate it. For instance, someone with the sense of touch can grasp a piece of cake and feel that it is being crushed, but someone without the sense of touch would need to be watching the cake to realize the same thing. This research gives amputee patients a better connection to the world and is the next step in restoring patients to their full capabilities.Sources:http://www.npr.org/sections/health-shots/2016/10/13/497716281/brain-implant-restores-sense-of-touch-to-paralyzed-manhttp://stm.sciencemag.org/content/early/2016/10/12/scitranslmed.aaf8083.abstracthttp://www.upmc.com/media/NewsReleases/2016/Pages/bci_scitransl-lms.aspxhttps://sciencelife.uchospitals.edu/2016/10/13/researchers-help-paralyzed-man-regain-sense-of-touch-through-a-robotic-arm/http://www.nature.com/news/pioneering-brain-implant-restores-paralysed-man-s-sense-of-touch-1.20804