Ideas in movement: The next wave of brain-computer interfaces

VOLUME 22 | NUMBER 1 | JANUARY 2016 NATURE MEDICINE Seconds after a brief smile of anticipation flashed across her face, Jan Scheuermann moved a bar of chocolate toward her mouth by controlling a robotic prosthetic arm. Finally, she took a bite. As she relished the taste, the team of neuroscientists and engineers in the room erupted in applause. It was no small feat for Scheuermann to feed herself. Fourteen years before this 2012 experiment, she had been diagnosed with spinocerebellar ataxia, which causes progressive and irreversible paralysis. In the intervening years, she had gradually lost the ability to move her arms and legs. About three months before her chocolateeating triumph, scientists at the University of Pittsburgh in Pennsylvania had implanted into her primary motor cortex two tiny arrays consisting of 100 electrodes, which enabled her to control the robotic arm— or Hector, as she had named it. Before the surgery, Scheuermann, who was 53 at the time, proclaimed that her goal would be to feed herself a sweet treat. In the following weeks, Scheuermann practiced using her brain to control Hector, moving the arm forward and backward, turning the wrist and closing the hand. Finally, she used Hector to feed herself a snack. As she noshed on her first glorious bite of the chocolate candy bar, she said, “One small nibble for a woman; one giant bite for BCI.” A BCI, or brain-computer interface, sounds like something from science fiction. After someone becomes paralyzed, either through progressive illness such as amyotrophic lateral sclerosis (ALS) or because of a sudden accident that severely injures the spinal cord, a BCI offers the possibility of restoring movement and, eventually, some level of independence. The first BCI was used by a paralyzed person to play a computer game, serving as a proof of concept that these devices could translate thought into action; since then, neuroscientists and engineers have developed superior systems1. The most recent models enable a user to move a prosthetic arm with up to ten degrees of freedom, which includes separating individual fingers and moving the thumb on a prosthetic hand2. As BCIs advance, however, it is becoming more of a challenge for these systems to interpret the more extensive neurological output from users’ brains and translate them into motion. To make this interpretation more efficient, neuroscientists are studying the ways in which healthy individuals use different types of sensory feedback, including what they can see and feel, and how they can sense their bodies in space to control their actions. Ultimately, the goal is to give people with paralysis the ability to move in the fullest extent possible, either by using robotic prostheses or by restoring movement to their own limbs.