A paralyzed man with no voluntary control of his muscles, including his eyes, has regained the ability to communicate in full sentences through a brain implant. After months of practice with a brain implant, the man was able to compose a full sentence: “I love my cool son.” The findings are detailed in a Nature Communications paper published Tuesday (March 22).
A few years ago, the now 36-year-old man was diagnosed with amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease that kills off motor neurons. Patients with ALS gradually lose the ability to speak, eat, and breathe on their own, and typically die within five years of their diagnosis. But even when completely paralyzed, many ALS patients can still see, hear, and smell—abilities that researchers rely on when developing new communication devices.
In 2016, a team of researchers reported that, with the help of a brain implant that detected attempts to move her hand, a woman with ALS was able to communicate in complete sentences through a computer. But Science notes that the woman still had partial control of her eye and mouth movements, giving her a greater ability to communicate than the man described in the new study.
At first, the man was able to use eye movements to communicate with his family, but he began losing control over his eye muscles in 2017. The parents of the patient contacted doctors at the nearby University of Tübingen in Germany, asking for a new method of communication, according to The New York Times.
In 2017, when the patient was still able to consent via eye movements, the researchers surgically implanted two 3.2-square-millimeter microelectrode arrays into his primary motor cortex, the part of the brain involved in planning and executing voluntary movements. By late 2018, the man’s ALS progressed to the point that he became completely locked in—that is, unable to move any muscles including his eye—reports The Guardian.
After his brain implant, when the doctors asked the man to move his hands, feet, or arms, the neural signals that followed weren’t consistent, meaning they couldn’t be used as code to answer yes or no questions. After three months of unsuccessful attempts, Niels Birbaumer, a retired neuroscientist at the University of Tübingen and a coauthor of the work, suggested trying auditory neurofeedback, a technique that teaches patients to manipulate their brain activity with real-time feedback as to whether they’re succeeding. The researchers decided to present man with a “target tone”—the note the patient was instructed to listen for and respond to with his neural activity. They then generated a separate tone based on brain activity detected by the implanted electrodes and became higher in pitch as more neurons fired, reports Science. Over time, the man learned to modulate the tone by imagining specific actions, with the goal of making the second tone match the first.
The researchers saw results almost immediately, the Times reports. The patient was able to change the neurally generated tone on his first day trying the task. He successfully matched the target tone after one week.
Over the next year, the patient modified the tone-matching skill to generate words and sentences by selecting letters from a computer program one letter at a time. By holding a tone “high” or “low,” the man could indicate “yes” or “no” to groups of letters, then later, individual letters, according to Science. Eventually, he was able to compose whole, intelligible sentences, which included “Goulash soup and sweet pea soup,” “I would like to listen to the album by Tool loud,” and his message to his son.
When the doctors asked what the patient was imagining to alter his own brain activity, he replied: “Eye movement,” according to the Times.
Ujwal Chaudhary, a biomedical engineer at the University of Tübingen and the Wyss Center for Bio and Neuroengineering in Geneva, tells the Times that he and his colleagues “could not believe that this is possible.” He is now managing director at ALS Voice gGmbH, a neurobiotechnology company based in Germany, and no longer works with the patient.
The findings come with a history of controversy. Birbaumer was accused of scientific misconduct for similar work three years ago. The researchers’ previous work, which reported that completely paralyzed people with ALS could communicate with a brain-computer interface (BCI), was retracted from PLOS Biology after a whistleblower at the University of Tübingen claimed that the researchers' findings were not replicable. This prompted an investigation by the German Research Foundation, the largest research funding institution in Germany, which found that the team had kept incomplete records of their analyses, had only partially recorded videos of their examinations of the patients, and had made false statements, STAT reports.
According to the Times, the German Research Foundation has no knowledge of the publication of the current study and will investigate it in the coming months. In an email to the Times, a representative from Nature Communications declined to comment on the details of how the study was vetted but expressed confidence in its results. “We have rigorous policies to safeguard the integrity of the research we publish, including to ensure that research has been conducted to a high ethical standard and is reported transparently,” the representative writes.
“I would say it is a solid study,” Natalie Mrachacz-Kersting, a BCI researcher at the University of Freiburg in Germany who was not involved in the study, tells the Times. She says she had prior knowledge of the retracted papers.
Before this work, researchers did not know whether people in the completely locked-in state also lost the ability to generate commands for communication, study coauthor Jonas Zimmermann, a senior neuroscientist at the Wyss Center, tells The Guardian. “Successful communication has previously been demonstrated with brain-computer interfaces (BCIs) in individuals with paralysis. But, to our knowledge, ours is the first study to achieve communication by someone who has no remaining voluntary movement and hence for whom the BCI is now the sole means of communication.”
The researchers at the Wyss Center are continuing to work with the patient but tell Science that his ability to communicate has deteriorated. The patient mostly answers “yes” or “no” questions and his ability to spell has decreased. The researchers say that scar tissue around the implant is likely to blame, as it obscures neuronal signals. Decreased cognitive function from years of being unable to move or speak may also play a role. The research team is committed to maintaining the device as long as the patient is able to use it, reports Science.