A brain-computer interface that didn't rely on vision alone but also mimics the sensation of touch dramatically improved the ability of a person with tetraplegia to manipulate objects with a brain-controlled robotic limb. The participant performed various tasks at a level comparable to able-bodied humans. Prosthetic devices controlled by brain-computer interfaces (BCIs), which measure movement-related brain activity from implanted electrodes and translate it into the conscious control of a robotic limb, have enabled some paralyzed users to regain functional movement. However, the use of BCI-controlled systems is limited. They often rely on visual cues alone and lack the critical sensory feedback from being able to feel the objects being grasped. To address this, Sharlene Flesher et al. added an afferent channel to the BCI to mimic sensory input from the skin of a hand, resulting in a system that both "reads" and "writes" information to the brain. Flesher et al.'s bidirectional BCI reads neural activity from the brain's motor cortex to control the robotic arm. At the same time, sensors on the robotic hand's "skin" recode the mechanical forces it experiences, transmitting them back to the somatosensory cortex through intracortical microsimulation, allowing the user to perceive tactile sensations as if they were generated from their own hand. The male participant in this study was a 28-year-old who had sustained an injury 10 years prior. With the new BCI, he substantially improved trial times for a series of upper-limb assessments involving moving different shaped objects, including emptying a cup full of bits of paper and plastic that was on the right of a table into an empty cup on the left. In all tasks, his times were reduced by half compared to doing the same work without a BCI that provided tactile feedback, from a median time of 20.9 seconds to 10.2 seconds. "The results of Flesher et al. open up many avenues of inquiry, including the possibility of advancing robotics and the development of tactile artificial skins into clinical use, to transhumanist questions about augmenting human capabilities with nonbiological sensors," writes Aldo Faisal in a related Perspective.
###
Journal
Science