A 36-year-old German man in full confinement was fitted with a new brain-computer interface (BCI) system based on auditory feedback. Humans have learned to modify their brain activity in response to this auditory feedback to form simple messages. According to a recent article in Nature Communications, he used this ability to order beer, have caregivers play his favorite rock band, and connect with his young son.
ICBs interact with brain cells, recording the electrical activity of neurons and translating these signals into action. These systems typically include sensor electrodes for recording neural activity, a chip set for transmitting signals, and computer algorithms for signal translation. BCIs can be external, such as medical electroencephalograms (EEGs), where electrodes are placed on the scalp or forehead using a wearable cap, or they can be implanted directly into the brain. The first method is less invasive but possibly less accurate because more noise interferes with the signals; The second requires brain surgery, which can be risky.
But for many paralyzed patients, the world has seen two important parameters on the front. In March 2021, the press reported on Neuralink’s display of a monkey playing pong using a brain implant that was connected wirelessly to a game computer. In April 2021, researchers from the BrainGate consortium successfully administered high-bandwidth wireless BCI in two human subjects with quadriplegia.
This latest study used wire-implanted BCI. People with amyotrophic lateral sclerosis (ALS), colloquially known as Lou Gehrig’s disease, are often paralyzed and unable to communicate, despite being cognitively functional. Several assistive devices have been developed to help restore contact, including BCIs that rely on eye movements. But patients who are in complete confinement have lost even that small part of their motor control.
The German man in the study was diagnosed with progressive muscle wasting in August 2015, a type of amyotrophic lateral sclerosis that selectively affects motor neurons. Within months he was unable to walk or communicate verbally, and in July 2016 he was on artificial ventilation and fed through a tube. The man initially communicated via an eye movement assistive device, but his condition deteriorated.
After the man’s family realized that it was only a matter of time before he completely lost control of his eye movement, the man’s family asked co-authors Niels Bierbaumer of the University of Tübingen and Ojwal Chaudhry of ALS Voice gGmbH in Germany what alternative options they had. An implanted BCI was considered the best option, and neurosurgeons in Munich performed the operation in March 2019.
They placed two arrays of microelectrodes in the patient’s left motor cortex (dominant side) to detect nerve signals, which can be sent over a wired connection to a computer for processing. NeuroKey then decodes this data and outputs it as auditory feedback tones, with the patient’s vision being very limited. Soon the patient learned to adjust the pitch and eventually to adjust the rate of nerve excitation to match the frequency of the reactions. After several months of training, the man can choose letters and spell words to communicate.
The first message was a simple thank you to Bierbaumer and the rest of the team. Other messages were about the man’s care preferences: he would ask for a head massage or more gel on his eye (which was prone to dryness) and ask for a higher position of the head around visitors. He even made suggestions to improve the performance of the spelling system.
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