Using a brain-controlled robotic suit, a quadriplegic man is able to move his arms and walk. These early results are promising – even astonishing – but authors note that the system is far from clinical application and needs improvements before becoming available to the public.
According to a two-year trial published in The Lancet Neurology, the robotic suit, called an exoskeleton, is operated by recording and decoding brain activity. The patient shown in the video above suffered from a cervical spinal cord injury and is nearly completely paralyzed from the shoulders down. About 20% of patients with this type of injury are left with all four limbs completely or partially paralyzed.
In the trial, two recording devices were implanted between the brain and skin above the patient’s sensorimotor cortex, a brain region in charge of sensation and motor control. Each implant collected neural activity from an array of 64 electrodes and transmitted these signals through a decoding algorithm. When the patient thought about making a movement, the system allowed him to send these commands to the exoskeleton to turn thought into action.
The two brain implants were inserted above the patient's sensorimotor cortex.
Photo credit: Fonds de Dotation Clinatec
"Ours is the first semi-invasive wireless brain-computer system designed for long term use to activate all four limbs," says Dr. Alim-Louis Benabid, President of the Clinatec Executive Board, a CEA laboratory, and Professor Emeritus from the University of Grenoble, France. "Previous brain-computer studies have used more invasive recording devices implanted beneath the outermost membrane of the brain, where they eventually stop working. They have also been connected to wires, limited to creating movement in just one limb, or have focused on restoring movement to patients' own muscles."
Over the span of 24 months, the patient performed various tasks to train the algorithm to comprehend his thoughts and to increase the number of movements he could make. First, he controlled a virtual avatar in a video game (similar to the game Pong) and reached for targets with the avatar. Eventually, he used the exoskeleton to reach for items, and walk.
The patient also learned to turn on the brain switch to begin walking as an avatar, and to make the exoskeleton walk. Two months after surgery, using the exoskeleton, he succeeded 73% of the time. Using the avatar and exoskeleton combined, he covered a total of 145 meters with 480 steps.
After months of training in the lab and at home using the avatar, the patient performed more complex tasks. Five months after surgery, he was able to reach out to cubes with one hand (moving in 3D). Sixteen months after surgery, he could use both hands to touch targets on cubes and rotate both wrists.
Three more patients have been recruited for the trial and eventually, researchers hope to allow patients to walk and balance on their own without using ceiling suspensions.
Future studies will reveal much more about how the sensorimotor cortex controls virtual and real-life movements. In the trial, authors found that the patient performed tasks with about a 10-20% greater success rate using the exoskeleton compared to the avatar; meaning that richer feedback from the real, physical world may be key to translating brain activity into movement.