These electrical signals – the same as those a doctor looks at when running an electroencephalogram (EEG) test – were sent to a computer, which “decoded” the brain waves.
Although Fritz is now only able to walk a short distance with a mechanical aid, researchers at the University of California have said the technology represents a promising yet incremental achievement in the development of brain-computer interfaces.
Mental training was initially required to reactivate the participant’s ability to use his brain power to walk, according to the study.
First, the patient was taught to control a virtual reality “avatar” with his brainwaves and given exercises to recondition and strengthen his leg muscles.
The participant later practiced walking while suspended 5cm above ground, so he could freely move his legs without having to support himself. On his 20th visit, equipped with a support system to avoid falls and take some of his body weight, he managed to put one foot after the other along a 3.66 m (12 ft) walking course.
Spinal cord stimulation using BCIs offers hope of regaining voluntary lower extremity movements to those with SCI. It would enable intuitive and direct brain control of walking via an external device. “However, independent over-ground walking is still some way off, not least because the issue of maintaining balance hasn’t yet been addressed”.
Spinal cord injuries only sever the neural connection to the legs, but the region of the brain that is responsible for sending the command to move the legs is not affected.
The breakthrough is owed to a functional electric stimulation (FES) device, which essentially acts as a communicator between Fritz’s brain and legs.
Their novel approach permitted the young man, who has complete paralysis of both legs due to spinal cord injury, to take steps without relying on manually controlled robotic limbs.
“Walking is a very fundamental behavior for us”, he said, pointing out that sitting can affect a person’s cardiovascular health or their bladder control. The computer works in such a way that it interprets received brain waves as an intention to either walk or stand still.
Researchers said the goal of testing a BCI system is to develop a brain implant that can communicate with electrodes in the legs, however researchers said a noninvasive version allows for better testing of the method.
“We hope that an implant could achieve an even greater level of prosthesis control because brain waves are recorded with higher quality”, he added.
Dr. Miguel Nicolelis, professor of neurobiology and the director for the Center of Neuroengineering at Duke University, said the study was exciting, but emphasized that the dramatic results will need to be replicated in other paraplegic patients.