Speak with your mind!

▎WuXi AppTec Content Team Editor You lie in bed and hear your loved ones surrounding you and talking about your condition
.

You want to be part of their conversation, but even with all your might, you can't make a sound, open your eyes, or even control your facial muscles to make even the slightest expression
.

Your consciousness is very clear, but you have completely lost the ability to control your body and express yourself to the outside world.
.
.
This is not a nightmare, but the reality of amyotrophic lateral sclerosis (ALS, commonly known as ALS) patients in a locked state portraiture
.

As a rare but fatal neurodegenerative disease, patients with ALS gradually lose control of their muscles.
Some patients eventually lose control of their eye and facial muscles, and lose the ability to communicate completely locked in their own bodies.
, until the end of life
.

In Germany, a 36-year-old man faced such a situation
.

He was diagnosed with ALS in August 2015, and his health has taken a nosedive since then
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After just 4 months, he lost the ability to speak and walk; in the second year, the patient was unable to breathe on his own and needed a ventilator to survive
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▲ This patient from Germany communicates with the outside world through a brain-computer interface (Image source: Wyss Center) With the development of the disease, the patient's communication with others has also become a problem
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Early on, he was also able to use eye-tracking devices to form words and sentences by moving his eyes
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But since August 2017, with the decline in eye control, he has been unable to use the device, and can only answer "yes" and "no" questions by eye movement
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Since the complete loss of eye movement ability is inevitable, the patient told the research team at the University of Tübingen that he hopes to have a brain-computer interface implanted to maintain communication with his family, especially his young son
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In 2016, such a device already helped a female ALS patient communicate with the outside world with her mind, but no one knows whether such a strategy will work when the brain has completely lost control of the body
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After the family signed off, the research team implanted two electrode arrays with a side length of only 3 mm into the patient's motor cortex
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Each array contains 64 needle-like electrodes used to detect neural signals
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▲ This device consisting of electrodes is used to record the patient's brain activity (Image source: Reference [1]) Although the patient can no longer move his body at this time, his brain can still tell the body how to move, and the electrodes capture this process Generated brain activity signals
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In theory, two different neural signals can correspond to a "yes" or "no" answer
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But after surgery, neither asking patients to imagine moving their hands, feet or eyes would translate into sufficiently clear answers
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It wasn't until 3 months later that the research team found an effective way to give feedback
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They took advantage of the patient's brain's auditory neurofeedback system, which trained the patient to control the firing rate of neurons after hearing a sound so that the frequency of the feedback tone matched the target tone
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If the discharge rate was above the upper threshold for more than 0.
25 seconds, the patient said "yes"; conversely, if the discharge rate was continuously below the lower threshold for 0.
25 seconds, the patient said "no"
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▲The video demonstrates how the patient responds to the sound (video source: Reference [1]).
Based on this process, a spelling program reads the letters of the alphabet, and the patient gives a yes or no answer through neural signals to choose a specific letters of
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Of course, predictably, the process is rather slow, with patients only able to select one letter a minute
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In addition, the accuracy of the technique was limited: During the 135-day trial period, patients matched target sounds on 107 days, of which only 44 days produced meaningful sentences
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One of the corresponding authors of the paper, Dr.
Jonas Zimmermann of the Wyss Centre for Biological and Neural Processes, also said that the technology still has shortcomings: it is not only expensive, but also time-consuming and labor-intensive
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For example, caregivers need to be trained to familiarize themselves with the system and validate patient feedback
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This way, patients can use the implanted device to communicate with others
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But for such a patient who is completely enclosed in his own world, being able to communicate with family and doctors through meaningful sentences is a huge leap in itself
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After using the system for 3 weeks, he "speaked" meaningful sentences for the first time and asked a caregiver to help him move his body
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In the following year, he produced many more complete sentences
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He expresses affection to his family (“I love my cool son”), tells his caregivers what he wants to eat through the esophagus (“Hungarian beef soup and pea soup”), and gives comments to the system (“Turn on word recognition” ”)… For the patient, it is the only window through which he can express his inner world to others
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▲The situation of patients using this device to generate sentences (Image source: Reference [1]) Unfortunately, the effect of this device gradually weakened over time
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Now, he can only use the device to answer "yes" and "no" questions
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The researchers say that this may be because scar tissue around the implant blocks the transmission of nerve signals; in addition, another possible reason is the weakening of the patient's brain's own thinking
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Currently, the system is still in the preclinical stage, and the authors hope to conduct clinical trials in the near future
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Before being promoted to clinical use, further demonstration of its long-term, applicability and safety in other patients is required
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A related paper was published in the journal Nature Communications
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"This study shows that it is possible to write sentences even when completely paralyzed and unable to use the eyes and muscles to communicate with the outside world,
"
said study leader Professor Niels Birbaumer of the University of Tübingen in Germany
.

Reference: [1] Chaudhary, U.
, Vlachos, I.
, Zimmermann, JB et al.
Spelling interface using intracortical signals in a completely locked-in patient enabled via auditory neurofeedback training.
Nat Commun (2022).
https:// doi.
org/10.
1038/s41467-022-28859-8[2] Brain implant helps completely 'locked-in' man communicate.
Retrieved Mar 25th, 2022 from https://medicalxpress.
com/news/2022-03-brain- implant-locked-in.
html[3] In a first, brain implant lets man with complete paralysis spell out thoughts: 'I love my cool son.
'.
Retrieved Mar 25th, 2022 from https:// content/article/first-brain-implant-lets-man-complete-paralysis-spell-out-thoughts-i-love-my-cool-son