Tech

A locked man who communicates in sentences just by thinking


When he met the man in February 2018, Chaudhary was trying to automate the communication system the family was using. The team connected an eye-tracking device to computer software that read out colors and row numbers, allowing the man to select letters one at a time using eye movements to spell out words.

But as the man increasingly lost control of his eye movements, he also became less able to communicate using that device. “We recommend transplanting [an electrode],” Chaudhary said. Tiny electrodes can be implanted in the brain to record the electrical activity of brain cells directly. The procedure – which tends to involve drilling a hole in the skull and removing the protective layers of the brain – comes with a small risk of infection and brain damage. So it’s a last resort, Birbaumer said. “If [non-invasive] BCI and eye tracking devices don’t work anymore, there’s no other choice,” he said.

Chaudhary said the man agreed to the procedure using eye movements. His wife and sister also agreed. By the time the procedure was approved by the ethics committee and the German Federal Institute for Research in Medicines and Medical Devices in late 2019, the man had already lost the ability to use the eye-tracking device. In March 2019, surgeons implanted two tiny grids of electrodes, each 1.5 millimeters across, into the man’s motor cortex — an area at the top of the brain responsible for motion control.

Signal to command

A day after the electrodes were inserted, the team began trying to help the man communicate. At first, the man was asked to imagine performing body movements — this helped the other recipients control prosthetic limbs and exoskeletonand is the approach Elon Musk’s Neuralink Company implementation plan. The idea is to get a reliable signal from the brain and convert it into some kind of command.

But the team couldn’t make it work. 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 to control it. In this case, when the electrodes in the man’s brain recorded an increase in activity, the computer played an increased sound. Decreasing brain activity will produce a diminishing sound.

“Within two days, he was able to increase and decrease the frequency of the sound,” says Chaudhary. “It’s just unbelievable.” The man eventually learned to control his brain activity so that he could sound an increased tone to signal “yes” and a tone decrease to signal “no”.

The team then introduced software that simulated the paper-based computer system the man had originally used to communicate with his family. The man will hear the word “yellow” or “blue”, for example, to select a block of letters to choose from. He will then play individual letters and use increasing or decreasing tones to select or remove each letter (see video).

Efforts

In this way, the man was soon able to communicate whole sentences. “[His family] very excited to hear what he has to say,” Chaudhary, who, along with his colleagues, said their findings in the journal Nature Communications on Tuesday. One of the first sentences the man spelled was translated as “boys, it works very easily.”

Communication was still slow – it took about a minute to select each letter. But the researchers believe the device has significantly improved the man’s quality of life. He ordered specific meals and soups, instructed carers on how to move and massage his feet, and asked to watch movies with his young son, for example. One sentence is translated as “I love my wonderful son.”

“Many times, I was with him until midnight or past midnight,” Chaudhary said. The “last word is always” beer. “

One of the first sentences the man spelled was translated as “boys, it works very easily.”

Chaudhary envisions developing a list of frequently used words that could eventually allow software to automatically fill in a man’s words as he spells them, for example. “There are ways that we can make it faster,” he said.

No one knows how long the electrodes will stay in the man’s brain, but other studies have found that the same electrodes still work five years after being implanted in another person. But for a self-contained person, “one day can make all the difference,” says Kianoush Nazarpour at the University of Edinburgh, who was not involved in the work. “It’s a fundamental opportunity for them to regain choice and control over their lives,” he said. “A high-quality day can be really important to that person.”

Nazarpour thinks the technology could be made available regularly to people in a similar lockdown within the next 10 to 15 years. “For someone completely disconnected from communication, even a “yes”/“no” has the potential to be life-changing,” he says.

Brian Dickie, director of research development at the Motor Neuropathy Society in the UK, agrees that this timeline is realistic. But he wondered how many people with motor neuron disease — of which ALS is the most common — could benefit from such BCIs.

Steps back

The man who received the BCI had a form of ALS called progressive muscular atrophy (PMA). This form of the disease tends to target the motor nerves that travel from the spine to the muscles, leaving the person unable to control their muscles. But about 95% of ALS cases also involve degeneration of the motor cortex in the brain, says Dickie.



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