In another groundbreaking study published last year, Jaimie Henderson and several colleagues, including biomedical engineer Francis Willett and electrical engineer Krishna Shenoy, reported an equally impressive but entirely different approach to neural interface communication. Scientists recorded neurons firing in Dennis DeGray’s brain as he visualized himself writing words with a pen on a notepad, trying to recreate the distinct hand movements required for each letter . He mentally wrote down thousands of words so that the system would reliably recognize the unique patterns of neural activity specific to each letter and produce words on a screen. “You really learn to hate M’s after a while,” he told me with characteristic good humor. In the end, the method was extremely effective. DeGray was able to type at up to 90 characters or 18 words per minute, more than double the speed of his previous efforts with a cursor and virtual keyboard. He is the fastest mental typist in the world. “Sometimes I go so fast it’s just a big blur,” he said. “My concentration hits a point where it’s not uncommon for them to remind me to breathe.”
To date, achievements in brain-computer interfaces rely on a mix of invasive and non-invasive technologies. Many scientists in the field, including those who work with DeGray, rely on an array of surgically integrated tip electrodes produced by a Utah-based company, Blackrock Neurotech. The Utah Array, as it’s called, can differentiate signals from individual neurons, providing more precise control of connected devices, but the surgery it requires can lead to infection, inflammation and scarring, which may contribute possible degradation of signal strength. Interfaces that reside outside the skull, such as headsets that rely on EEG, are currently limited to eavesdropping on the collective firing of groups of neurons, sacrificing power and precision for safety. To further complicate the situation, most neural interfaces studied in the lab require bulky hardware, cables, and an entourage of computers, whereas most commercially available interfaces are essentially remote controls for video games, toys, and rudimentary applications. These commercial headsets don’t solve any real problems, and the most powerful systems in clinical studies are too impractical for everyday use.
With this problem in mind, Elon Musk’s company Neuralink has developed an array of flexible polymer wires studded with more than 3,000 tiny electrodes connected to a wireless radio and a signal processor the size of a laptop. bottle, as well as a robot capable of surgically implanting the wires into the brain, avoiding blood vessels to reduce inflammation. Neuralink has tested its system on animals and said it will begin human trials this year.
Synchron, which is based in New York, has developed a device called Stentrode that does not require open-brain surgery. It is an array of four centimeter self-expanding tubular electrodes, which is inserted into one of the main blood vessels of the brain via the jugular vein. Once in place, a Stentrode detects local electric fields produced by nearby groups of neurons in the motor cortex and relays the recorded signals to a wireless transmitter built into the chest, which transmits them to an external decoder. In 2021, Synchron became the first company to receive FDA approval to conduct human clinical trials of a permanently implantable brain-computer interface. So far, four people with varying levels of paralysis have been given stentrodes and used them, some in combination with eye tracking and other assistive technologies, to control unattended personal computers at home.
Philip O’Keefe, 62, from Greendale, Australia, received a Stentrode in April 2020. Due to amyotrophic lateral sclerosis (ALS), O’Keefe can only walk short distances, cannot move his arm left and loses the ability to speak clearly. At first, he explained, he had to focus intensely on the imaginary movements needed to make the system work – in his case, thinking about moving his left ankle for different durations. “But the more you use it, the more it’s like riding a bike,” he said. “You get to a stage where you don’t think too much about the move you need to make. You think about the function you need to perform, whether it’s opening an email, scrolling through a webpage, or typing letters. In December, O’Keefe became the first person in the world to post on Twitter using a neural interface: “No need for keystrokes or voices,” he mentally wrote. “I created this tweet just thinking about it. #helloworldbci”
Thomas Oxley, neurologist and founding CEO of Synchron, believes future brain-computer interfaces will fall somewhere between LASIK and pacemakers in cost and safety, helping people with disabilities regain the ability to engage with their physical environment and an evolving digital environment. “Beyond that,” he says, “if this technology allows anyone to interact better with the digital world than with a regular human body, that’s where it gets really interesting. To express emotion, to express ideas, everything you do to communicate what’s going on in your brain has to go through muscle control. Brain-computer interfaces will eventually allow a passage of information that goes beyond the limits of the human body. And from that perspective, I think the capacity of the human brain will actually increase.