In an article for the journal Scientific Reports, a team of researchers reports that the development a brain-machine interface that allows a pair of rhesus macaques to navigate in robotic wheelchairs using only their thoughts.
But before we get to how the monkeys are able to control the wheelchairs, it's important to understand just what a brain-machine interface (BMI) is, and how it works. We know the mind is a powerful thing. But scientists who are pioneering the development of BMIs aim to make it even more powerful. BMIs use electrodes to capture brain waves and then translate them into signals that can operate robotic devices and computers. The idea is to give a person the ability to control equipment without using his or her hands or feet, or even moving a muscle. Instead, the user of a BMI simply would think about what he or she wanted to do, and the BMI would guide the machine to perform the task.
It's a technology that holds great promise for people who have spinal cord injuries or neurological diseases, because a BMI could circumvent the damaged portions of their nervous systems and direct a robotic arm, a powered exoskeleton or a wheelchair for them.
A Marriage of Monkey and Machine
Scientists have been working on BMIs for decades, and in recent years, they've developed systems that have enabled primates to use their brain activity to control artificial limbs. But it would be even better if paralyzed people could also use the technology for whole body navigation—that is, to move around in space.
But now, it looks as if whole-body navigation with a BMI may be the wave of the future, thanks to the Duke University's experimentation with macaques. Check out this video showing how the team headed by Dr. Miguel Nicolelis, a professor of neuroscience at Duke School of Medicine, developed the technology:
It wasn't easy for the scientists to get to this point. Nicolelis's team started back in 2012 by surgically implanting hundreds of hair-thin microfilaments in the brains of two monkeys. Then, they trained the animals by putting them in wheelchairs and pushing the chair for them to reach a goal — a bowl containing grapes. During that phase, the implanted electrodes detected the monkeys' electrical brain activity. The researchers recorded that activity and then programmed a computer system to translate the signals into digital motor commands, which were capable of controlling the movements of a robotic wheelchair.
At that point, the monkeys started learning how to control the wheelchair just by thinking. Over time they got better and better at it. And in the process, the Duke researchers noticed something intriguing. The primates' brain signals indicated that they were weren't just guiding movements of the wheels, but contemplating the distance to the bowl full of grapes as they did.
"This was not a signal that was present in the beginning of the training, but something that emerged as an effect of the monkeys becoming proficient in this task," Dr. Nicolelis said in a press release. "This was a surprise. It demonstrates the brain's enormous flexibility to assimilate a device, in this case a wheelchair, and that device's spatial relationships to the surrounding world."
Bridging the Primate Gap to Humans
The study also demonstrates the promise of brain implants, which are better at picking up the brain's electrical activity than electrodes attached to the scalp. "We show clearly that if you have intracranial implants, you get better control of a wheelchair than with noninvasive devices," Dr. Nicolelis said in the press release.
Alexandra Bennewith, an official with the United Spinal Association, praises the advance. She works for a New York-based advocacy organization that pushes for innovations in wheelchairs and other medical devices to assist disability people with mobility.
"This shows that continued robust public and private funding for research is critical," she says via e-mail. "No-one can predict what next breakthrough intervention might be discovered, and what advancements might result in an improved quality of life for the 5.5 million people living with paralysis in the United States, including the 1.3 million people living with spinal cord injury."