A patient unable to make a move was recently able to communicate with his family by typing short sentences on a keyboard with the sheer force of his mind. These results, made possible by a brain implant, overturn previous assumptions regarding the communication skills of people who have lost all voluntary muscle control.
In its later stages, amyotrophic lateral sclerosis (ALS) can lead to extreme isolation. Because of this neurological disease, people indeed lose control of their muscles and following a while, communication becomes more and more difficult. Some, however, may use an eye-tracking camera to select letters on a screen (like Stephen Hawking), when others can answer “yes” or “no” questions with subtle eye movements.
Unfortunately, most of these patients die within a few years of diagnosis, but some choose to prolong their life on a ventilator. These people can then spend months or even years hear without being able to communicate. This brings us to this study.
In Nature Communicationsresearchers report that for the first time, a man in this complete state of confinement was able to formulate simple sentences to communicate with his family thanks to an implant.
Change the frequency of a sound wave by the mind
It all started in 2016. At the time, the team of Dr. Mariska Vansteensel, from the University Medical Center in Utrecht, reported that a woman with amyotrophic lateral sclerosis (ALS) might spell sentences with a brain implant. capable of detecting attempted hand movements. However, this person still had a minimal control of certain muscles. Thus, it was still unknown at the time that a brain that had lost all control over the body might actually signal or not signal the desired movements in a sufficiently coherent way to allow meaningful communication.
The participant in this new study, a 36-year-old German, started working with a team from the University of Tübingen in 2018, when he might still move his eyes. Aware that he would soon be unable to do so, he asked the researchers to work on an implant allowing him to maintain communication with his family. His wife and sister provided written consent.
For this work, the researchers inserted two networks of electrodes into the part of the brain that controls movement. The team then turned to the process of neurofeedback, in which the patient’s neural activity was measured and presented to them in real time. The goal was for the latter to manage to self-regulate his neuronal activity supposed to underlie a behavior.
After several weeks of training, the man finally learned to generate brain activity that might change the frequency of a sound wave using a computer program. He then applied this same strategy to control a spelling program that allowed him to select letters one at a time to form words at an average rate of regarding one character per minute.
Slow but possible communication
By holding the tone high or low, the man might first “write” the words “yes” and “no” by focusing his neural activity on individual letters. About three weeks later, he would have finally managed to produce an intelligible sentence (a request for caregivers to reposition him). In the year that followed, the man had managed to pronounce dozens of sentences.
Of course, it wasn’t 100%. The patient would have succeeded in match a series of target tones with 80% accuracy only 107 times over the 135 days reported in the study. And he mightn’t produce an intelligible sentence only 44 times over these 107 days.
« We can only speculate regarding what happened on other days, the authors note. The participant might have fallen asleep or just wasn’t in the mood. Perhaps the brain signal was also too weak for the computer’s decoding system to be tuned optimally.
More work and ethical concerns
Study shows it’s possible to maintain communication with someone while they’re locked down by adapting an interface to its capacities thanks to an implant. However, hundreds of hours were spent designing, testing and maintaining the custom system. Also, additional work will obviously be necessary to make the technique more effective and, above all, affordable.
This new breakthrough also raises ethical questions. Discussing end-of-life care preferences is hard enough for people who can talk. It is therefore difficult to imagine this type of conversation and all that it involves with one of these devices that only allow you to speak three sentences a day. The misinterpretations might indeed have serious consequences.
On this point, the research team suggests that the participant’s medical care should not depend on this type of interface. And that such decisions should always be made by family members.
