A paralysed woman has learned to use a brain implant to communicate by thought alone. It is the first time a brain–computer interface has been used at home in a person’s day-to-day life, without the need for doctors and engineers to recalibrate the device.
“It’s special to be the first,” says HB, who is 58 years old and wishes to remain anonymous. She was diagnosed with amyotrophic lateral sclerosis (ALS) in 2008. The disease ravages nerve cells, leaving people unable to control their bodies. Within a couple of years of diagnosis, HB had lost the ability to breathe and required a ventilator. “She is almost completely locked in,” says Nick Ramsey at the Brain Center of University Medical Center Utrecht in the Netherlands.
When Ramsey met her, the woman relied on an eye-tracking device to communicate. The device allows her to choose letters on a screen to spell out words, but may not work forever – one in three people with ALS lose the ability to move their eyes. However, teams around the world have been working to develop devices that are controlled directly by the brain to help people like HB.
These devices work by reading brain activity and translating it into a signal that can control a computer or a robotic limb, for example. But so far, it has been difficult to make these devices fit into people’s daily lives. They tend to need recalibrating by a team of engineers on a daily basis, and many are so complex that they cannot work wirelessly.
“They have not actually been useful for anyone,” says Ramsey. “We thought, let’s make it simple and affordable for a patient who really needs it,” says Ramsey.
On the mind
His team’s device uses electrodes placed on the surface of the brain, just underneath the skull. This makes it more invasive than external devices like an EEG cap, but less so than traditional deep brain stimulation, which is used to treat Parkinson’s disease.
When brain activity is recorded by the electrode, a signal is fed through a wire to a small device, which can be implanted under the skin of the chest, like a pacemaker. This device then wirelessly sends a signal to an external computer tablet, which can transform it into a simple “click”. Other software installed on the tablet can allow the click to be used for various things, such as playing a game or using a speller to select words and communicate.
HB volunteered to have the system implanted last year. “I want to contribute to possible improvements for people like me,” she says.
The team implanted two electrodes on her brain – one over a region that controls movement of the right hand, and the other over an area that is used for counting backwards. After multiple training sessions, which involved using the device to play games such as whack-a-mole and Pong, as well as to spell words, the woman learned to control the device by imagining moving her hand to trigger a click.
She was able to generate a signal from day one, but six months later, she had an accuracy of 95 per cent, says Ramsey, who presented his work at the Society for Neuroscience annual meeting in San Diego, California, today. “The system really works,” he says. “It surprised us.”
Taste of freedom
Using the device to communicate is still a slow process – it can take a few minutes to spell a single word – but HB is getting faster with training. At first, it took her 50 seconds to select a letter – she can now do it in 20 seconds.
Although this is slower than using her eye tracker, she is able to use the implant outdoors. Eye trackers had struggled to pick up subtle eye movements when HB was in natural light, away from home, for example. “It made her feel very uncertain when she was travelling,” says Ramsey.
“Now I can communicate outdoors when my eye-track computer doesn’t work,” says HB. “I’m more confident and independent now outside.”
She has not yet learned to use the device by counting backwards – the electrode placed on this part of her brain is a back-up, ready to be used if the part of her brain involved in movement degenerates.
Taking back control
The device has pros and cons. Placing electrodes on the surface of the brain is a good compromise between using sensitive but invasive deep electrodes and superficial EEG, which sits on a person’s skull, says Nicholas Hatsopoulosat the University of Chicago in Illinois. And because the system is powered wirelessly, it is invisible to others – something that many candidates for brain implants say is important to them.
The uncomplicated nature of the system is what makes it so suitable for home use. “It’s an extremely simple system, and doesn’t require any fancy computers,” says Ramsey. The downside of this is that the device is unlikely to be able to be used for more complex tasks, such as controlling robotic limbs, for instance, says Andrew Jackson at Newcastle University in the UK. “There’s a limit to the amount of information you can get,” he says.
Having said that, it is a useful approach for those who are paralysed, whether from motor neuron diseases such as ALS or as the result of a severe stroke, for example. “For these patients, it could be a really important thing,” says Hatsopoulos.
Ramsey and his colleagues hope to trial the system in other individuals. Now that his team have improved the tablet’s software, Ramsey expects the next volunteer to be able to learn to use the device more quickly. More sophisticated software that is better able to predict and complete words based on the first couple of letters could also speed things up.
His team hopes to develop software that can translate clicks into other functions. “With the right software, we could use it to, for example, turn off the TV,” says Ramsey. “We could use icons to control appliances in the home. You could conceivably do a lot with a click.”
“My dream is to be able to drive my wheelchair,” says HB.
“She has had [the device] for a year now, and says that it is part of her, and she uses it a couple of times a week” says Ramsey. “She didn’t expect that it would turn out to mean so much to her.”
Read an interview with HB about her experience using the implant.