When he met the man in February 2018, Chaudhary tried to automate the communication system the family was already using. The team connected an eye-tracking device to computer software that would read out colors and row numbers so that the man could select letters one at a time using his eye movements to spell words.
But as the man lost more and more control over his eye movements, he was also less able to communicate with that device. “We suggested implantation [an electrode]’ says Chaudary. Small electrodes can be implanted in the brain to directly record the electrical activity of brain cells. The procedure — which usually involves drilling a hole in the skull and cutting away the brain’s protective layers — carries a small risk of infection and brain damage. So it was a last resort, Birbaumer says. “As the [non-invasive] BCIs and the eye trackers no longer work, there is no other choice,” he says.
The man agreed to the procedure through eye movements, Chaudhary says. His wife and sister also gave their consent. By the time the procedure was approved by an ethics committee and the German Federal Institute for Drugs and Medical Devices in late 2019, the man had lost the ability to use the eye-tracking device. In March 2019, surgeons implanted two small electrode grids, each 1.5 millimeters in diameter, into the man’s motor cortex — an area at the top of the brain responsible for controlling movement.
Convert signals into commands
The day after the electrode was implanted, the team began trying to help the man communicate. Initially, the man was asked to imagine making physical movements — this has helped other recipients master prosthetic limbs and exoskeletons, and is the approach Elon Musk’s company Neuralink plans to take. The idea is to get a reliable signal from the brain and translate it into some sort of command.
But the team couldn’t pull it off. After 12 weeks of trying, they scrapped the idea and decided to try an approach called neurofeedback instead. Neurofeedback works by showing a person their brain activity in real time so they can learn how to control it. In this case, when the electrodes in the man’s brain registered an increase in activity, a computer would play a rising sound tone. A drop in brain activity would play a descending tone.
“Within two days, he was able to raise and lower the frequency of a sound tone,” said Chaudhary, who says he visited the man in his home every weekday in 2019 until the coronavirus hit. “It was just incredible.” The man eventually learned to control his brain activity so that he could play a rising tone to indicate “yes” and a falling tone to indicate “no.”
The team then introduced software that mimicked the paper-based computer system the man had originally used to communicate with his family. For example, the man would hear the word “yellow” or “blue” to pick a block of letters from which to choose. He would then be given individual letters and use an ascending or descending tone to select or ignore each letter (see video).
In this way, the man was soon able to communicate in full sentences. †[His family] were so excited to hear what he had to say,” said Chaudhary, who along with his colleagues published their findings in the journal nature communication on Tuesday. One of the first sentences the man spelled was translated as ‘guys, it works so effortlessly’.
Communication was still slow – it takes about a minute to select each letter. But researchers believe the device has significantly improved men’s quality of life. He has asked for specific meals and soups, instructed caregivers to move and massage his legs, and asked to watch movies with his young son, for example. One sentence translated as “I love my cool son.”
“Often I was with him until midnight or past midnight,” Chaudhary says. “The last word was always ‘beer’.”
One of the first sentences the man spelled was translated as ‘guys, it works so effortlessly’.
Chaudhary envisions developing a catalog of commonly used words, eventually allowing software, for example, to autocomplete the man’s words as he spells them. “There are many ways we can make it faster,” he says.
No one knows how long the electrodes last in the man’s brain, but other studies have shown that similar electrodes still function five years after being implanted in other people. But for someone incarcerated, “one day can make all the difference,” says Kianoush Nazarpour of the University of Edinburgh, who was not involved in the work. “That’s a fundamental opportunity for them to regain choice and control over their lives,” he says. “A high quality day can be very important to that person.”
Nazarpour believes the technology could be routinely offered to similar incarcerated individuals within the next 10 to 15 years. “For a person who has absolutely no communication, even a ‘yes’/’no’ is potentially life-changing,” he says.
Brian Dickie, director of research development at the Motor Neurone Disease Association in the UK, agrees that this timeline is realistic. But he wonders how many people with motor neuron disease — of which ALS is the most common type — would benefit from such BCIs.
The man who got the BCI has a form of ALS called progressive muscle atrophy (PMA). This form of the disease tends to target motor nerves that travel from the spine to the muscles, preventing people from controlling their muscles. But about 95% of ALS cases also involve degeneration of the motor cortex in the brain, Dickie says.