Reports from the Heart of the Machine
Machine Heart Editorial Department
Patients with ALS in a "locked" state cannot even control eye movements. After installing the brain-computer interface, he made requests in German one by one.
Ujwal Chaudhary, a biomedical engineer at the University of Tübingen and the Wyss Centre for Biological and Neural Engineering in Geneva, looked at his computer in amazement as an experiment that had been underway for several years finally surfaced. A paralyzed man lies on his back in the lab with his head connected to a computer via cable. The synthesized voice pronounces the letters in German: "E, A, D..."
A few years ago, the patient was diagnosed with amyotrophic lateral sclerosis (ALS), which led to progressive degeneration of brain cells involved in exercise. He had lost even the ability to turn his eyeballs and was completely unable to communicate. Medically, he is in a state of complete "lockdown".
Through Dr. Chaudhary's experiments, patients learn to move by imagining his eyes —selecting letters from a computer. Spell out one letter at a time, one word per minute.
"Wegen essen da wird ich erst mal des curry mit kartoffeln haben und dann bologna und dann gefuellte und dann kartoffeln suppe," he wrote.
In 2014, an event called the Ice Bucket Challenge brought the Frozen Man community to a widespread spotlight. Over the years, researchers in many fields such as medical treatment and science and technology have made efforts to improve the lives of patients with frostbite.
Starting in 2018, a research team from the University of Tübingen began working with a participant with alzheimer's disease (amyotrophic lateral sclerosis (ALS), using brain implantation technology to enable participants to communicate with their families.
Frostbite is a progressive neurological disorder that affects nerve cells in the brain and spinal cord, causing muscles to lose control, and the disease progresses to the final stages that can cause patients to lose control of the muscles needed to move, speak, eat, and breathe.
The 36-year-old frostbite patient who participated in the study has a cute little son whose biggest desire is to communicate with his family, especially his own children.
Usually people with FROST can use eye tracking cameras to select letters on the screen to communicate. When the disease progresses to a later stage, patients can answer yes or no questions with subtle eye movements. But people with ALS who have completely lost muscle control, and even their ability to control their eye movements and breathing, cannot communicate in this way.
The research team at the University of Tübingen has built an implantable device that can read brain signals, which ALS patients can use to communicate. The study was published in Nature-Communications.
The study surgically implanted two 3.2 mm wide square "microelectrode arrays" in the cerebral cortex responsible for movement, the motor cortex. Each microelectrode array carries dozens of microneedles for recording neural signals, which are then fed into a connector that connects to the patient's skull. Externally, there is an amplifier on the connector that digitizes the information and sends it to the computer.
When the patient is unable to move, the implantable device is able to read the patient's brain signals and record their impulse to move. These brain signals are sent to computers in real time, which learn to classify these motor attempts as "yes" or "no" responses, allowing patients to answer questions asked by others. In addition, the device can read letters aloud to patients, who can answer "yes" or "no" to each letter to spell out words.
"This study answers the long-standing question of whether people with completely atresia syndrome (losing all autonomic muscle control, including movements of the eyes, mouth, etc.) also lose the brain's ability to communicate commands," said Dr Jonas Zimmermann, a neuroscientist at the Wyss Centre in Geneva, one of the study's authors.
At first, the study went through some failed experiments, such as when participants instructed participants to try to imagine movements of hands, tongues, or feet, and the device was unable to detect a consistent response.
The research team then tried to adopt the neurofeedback-based pattern shown in the figure below. This mode maps the spike rate metric (SRM) of one or more channels into the tone of auditory feedback. Participants can adjust the frequency at which neurons emit signals based on auditory feedback, and the higher the frequency, the higher the external tone, and set a threshold to express "yes" or "no."
Participants tried to adjust the tone for the first time on day 86 after the experiment began, followed by successfully modulating the neural signal emissivity on day 98 and matching the feedback frequency to the target for the first time. Using a neurofeedback strategy, from day 106 onwards, participants were able to modulate the firing rate and were able to use this method to select and spell letters.
The team searched for the most responsive neurons and then explored how each neuron changed as participants worked, adjusting the system accordingly.
After using the system for about 3 weeks, he uttered an understandable sentence – asking the paramedic to adjust his position. Over the next year, he expressed dozens of sentences at a rate of about one word per minute:
Goulash soup and sweet pea soup.
I want to listen to Tool loud's album.
I love my cool son.
......
However, this method also does not express the information completely accurately. Participants explained to the research team: "He adjusts his tone by moving his eyes, but he doesn't always succeed. In 107 of the 135 days of research experiments, he was able to match a series of target tones with an accuracy rate of about 80 percent, and in only 44 of those 107 days, he was able to utter comprehensible sentences."
Researchers at the Wyss Center will continue to work with this participant. However, the participant's spelling ability has declined, and now he mainly answers yes or no questions. The researchers say this may be because there is some scar tissue around the implanted device, masking some of the nerve signals. On the other hand, participants gradually lost the ability to control the device due to the lack of interaction with the external environment for a long time, their cognitive ability declined. But Zimmermann said the research team promised to maintain the device as long as participants continued to use it. This is the real meaning of this type of research.
Reference Links:
https://www.technologyreview.com/2022/03/22/1047664/locked-in-patient-bci-communicate-in-sentences/
https://www.science.org/content/article/first-brain-implant-lets-man-complete-paralysis-spell-out-thoughts-i-love-my-cool-son
https://www.ctvnews.ca/health/paralyzed-als-patient-communicates-using-brain-implants-in-new-clinical-study-1.5829966