Touch is a sense many of us take for granted. You can feel the fabric of a shirt or the warmth of a crackling fire without thinking twice.
Nathan Copeland, paralyzed in a car accident more than a decade ago, can now feel with the assistance of brain-controlled prosthetic limbs and chips implanted in his brain.
Copeland told the Associated Press the sensation feels like pressure or tingling. He was able to feel these sensations 84 percent of the time in tests.
Researchers from the University of Pittsburgh detailed the six months leading up to the breakthrough technology in October’s Science: Translational Medicine. Their findings bring us closer to prosthetic limbs that can actually provide tactile sensations.
“Intracortical microstimulation of the somatosensory cortex offers the potential for creating a sensory neuroprosthesis to restore tactile sensation,” the authors wrote in their research article, Intracortical microstimulation of human somatosensory cortex.
“Whereas animal studies have suggested that both cutaneous and proprioceptive percepts can be evoked using this approach, the perceptual quality of the stimuli cannot be measured in these experiments. We show that microstimulation within the hand area of the somatosensory cortex of a person with long-term spinal cord injury evokes tactile sensations perceived as originating from locations on the hand and that cortical stimulation sites are organized according to expected somatotopic principles. Many of these percepts exhibit naturalistic characteristics (including feelings of pressure), can be evoked at low-stimulation amplitudes, and remain stable for months. Further, modulating the stimulus amplitude grades the perceptual intensity of the stimuli, suggesting that intracortical microstimulation could be used to convey information about the contact location and pressure necessary to perform dexterous hand movements associated with object manipulation.”
Having a basic sense of touch is critical for tasks like picking up objects and manipulating them, said Robert Gaunt, University of Pittsburgh assistant professor of rehabilitation and the leader of the study.
Scientists are working on placing sensors in prosthetics that will allow feedback to and from those sensors. This is a bit trickier for amputees, but scientists are researching ways to wire nerves left in the remaining part of a natural limb directly to the robotic arm.
In patients with spinal cord injuries, messages can’t travel directly between the hand and the brain, so electrodes were implanted in the part of Copeland’s brain that controls what his hands feel. Electrically stimulating this part of his brain worked, despite the fact that his injury is more than 10 years old.
The Associated Press contributed to this report.