Thanks to a brain-computer interface, the man managed to formulate a series of sentences despite complete paralysis. The study published in Nature Communications
They are called brain-computer interfaces (or Bci acronym for Brain computer interface) and allow you to create a bridge between machines and the human brain. Using one of these devices, a 36-year-old man for whom any movement now made impossible by the progression of Amyotrophic lateral sclerosis (ALS) managed to communicate: I love my amazing son, he wrote with thought. The study on this patient, published in Nature Communicationswas conducted by a group of researchers from the Swiss Wyss Center for Bio- and Neuroengineering in Geneva and by the German company Als Voice gGmbH from Mossingen.
Locked in syndrome
Now this technological innovation could give an answer to people with
locked in syndrome
(of the latch or pseudo-coma), a rare neurological disorder characterized by a complete paralysis of the voluntary muscles in all parts of the body, except those that control the movement of the eyes. This disease can be a consequence of traumatic brain damage, diseases of the circulatory system, diseases that destroy the myelin sheath that lines nerve cells or drug overdoses. Among these, in fact, the ALS. When a person with ALS can no longer speak, he can use an eye tracking camera to select letters on a screen. As the disease progresses, questions can be answered with either subtle eye or facial muscle movements. But there may also come a time when even moving your eyes or face becomes impossible.
Electrodes implanted in the brain
the case at the center of the study just published. According to what he reports Kelly Servick, editor of Sciencethe patient began working with a research group at the University of Tübingen in 2018, when he could still move his eyes. She told the team she wanted an invasive implant to try and maintain communication with her family, including her young son. His wife and sister provided written consent for the surgery.
The first attempts
To try to bypass the paralysis, the researchers entered two square electrode arrays, 3.2mm wide, in a part of the brain that controls movement. When they asked the man to try moving his hands, feet, head, and eyes, the neural signals weren’t consistent enough to answer any questions, he says. Ujwal Chaudhary, biomedical engineer and neurotechnologist at the German non-profit organization ALS Voce.
Success thanks to neurofeedback
After nearly 3 months of unsuccessful efforts, the team tried the
neurofeedback
in which a person attempts to modify their brain signals to obtain a real-time measure of success. An audible pitch increased in pitch as the electrical activation of neurons near the implant accelerated, lower as it slowed down. The researchers asked the participant to change that tone using any strategy. On the first day, he could shift the tone and, by day 12, he could match it to a target. The researchers fine-tuned the system by looking for the most responsive neurons and determining how each changed with the patient’s efforts. By keeping the tone high or low, the man was therefore able to indicate if not in groups of letters, then in single letters. After about 3 weeks with the system, she produced an intelligible sentence: a request for caregivers to reposition it. Over the next year, she uttered dozens of sentences at a painstaking pace of about one character per minute: Goulash soup and sweet pea soup. I would like to listen to the Tool album out loud. I love my amazing son. Eventually she explained to the team that she modulated the tone by trying to move her eyes.
There are still many challenges to be faced
The absolute novelty of the study lies in the fact that for the first time it is shown, albeit in a single case, that even in a clinical state of complete locked-in it is still possible to use Bci technology in this invasive case, to communicate comments Donatella Mattia, neurologist and researcher in the field of Brain Computer Interfaces at the Santa Lucia Irccs Foundation in Rome. Indeed all previous studies and published in high impact factor journalsincluded cases of people with ALS able to use a Bci (even invasive) to communicate but still had some residual motility (for example eye movements) and therefore were in an incomplete locked-in state, adds the expert. There are still many challenges to be addressed, such as the reproducibility of success in other cases similar to this one, problems related to the variability in the accuracy and speed of the information processed by the system, the cost of this instrument, the invasiveness which still involves some surgical risk. Without a doubt, however, this study represents a fundamental step in the future of Bci technology as a tool to reunite these people in complete locked-in with their loved ones, he concludes.
However, the study shows that it is possible to maintain communication with a person while being blocked by adapting an interface to their abilities, says Melanie Fried-Oken, who studies the brain-computer interface at Oregon Health & Science University. “So beautiful.” But hundreds of hours went into designing, testing, and maintaining the custom system, she notes. “We are nowhere near bringing this into an assistive technology state that could be bought by a family.”
The demonstration also raises ethical questions, Klein says. Discussing preferences for end of life care is hard enough for people who can talk, he notes.
March 24, 2022 (change March 24, 2022 | 18:36)
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