A brain implant has restored touch in the hand of a paralyzed man, who described the sensations as mimicking natural touch, according to a new study. The device also helped him sense touch using a robotic hand, paving the way to improving artificial touch in neuroprosthetic limbs. Brain chips can electrically stimulate neurons to recreate the perception of touch, a technique known as intracortical microstimulation. While the tool has proven promising in animal studies, how life-like the artificial sensations actually feel remains an open question. Sharlene Flesher and colleagues studied the sensations felt by a 28-year-old man with tetraplegia from a spinal cord injury, who had electrodes implanted into the somatosensory cortex, the part of the brain that controls touch, including in the hands. Electrically stimulating this region bypassed his spinal cord injury, and evoked sensations like warmth and pressure originating from the upper palm and base of the four fingers on his right hand. He described 93% of the stimuli (such as pressing a cotton swab on the surface of the skin) as feeling "possibly natural." He was also able to sense touch when connected to a prosthetic limb, correctly identifying 84% of the time which individual prosthetic finger was being touched while blindfolded. The subject's sensations remained stable over the course of the six-month study. Flesher et al.'s findings suggest that electrical brain stimulation can help reestablish realistic touch in paralyzed and potentially amputee patients, which may guide the design of better neuroprosthetic limbs.
Science Translational Medicine