When patients suffer a spinal cord injury, they often become paralyzed as their brain is no longer able to communicate with the muscles in their body. Robotics hold the promise of replacing the functions of a person’s limbs, but the problem of controlling artificial limbs remains a challenge. Researchers have been able to implant sensors in the motor-control portion of a patient’s brain, but the resulting motions tend to be jerky and erratic. The patient has to consciously control every element of a desired movement.

Researchers at Caltech, Keck Medicine at the University of Southern California, and Rancho Los Amigos National Rehabilitation Center have been working together on a novel approach to this problem. The average person simply thinks of performing some task, and the body responds with a series of coordinated motions. The researchers chose to place sensors in the part of a paralyzed patient’s brain that deals with intention, rather than action. In other words, when the subject thinks about performing a given task, this triggers a set of signals that can result in smooth, natural movements.

The result of the experiment is that the subject can now shake hands or play “rock-paper-scissors” using the robotic arm. Future research will be needed to provide the touch feedback required to perform finer tasks such as drinking from a cup. But this new research gives hope that before too long, paraplegics will be able to control exoskeletons with just their thoughts, and thus regain their independence and freedom of movement.