Neuralink Nabs FDA Green Light to Implant in Second Patient

Only a week after Neuralink disclosed that its first patient implanted with the device was experiencing the tiny threads in the brain pull out of position, the company has received green light from FDA to implant the brain chip in a second person after a proposed fix to complications seen in its first patient.

The device, which is about the size of a coin, is implanted on the brain and uses 64 tiny threads equipped with over 1,000 electrodes to read neuron activity in the brain which is then connected with a computer or smart phone. Through the neuron activity, the chip can decode signals to control computers, smart phones, and tablets with thoughts alone. Neuralink received FDA approval to start its in-human trials for the device in 2023.

In late January 2024, the first chip was implanted in the brain tissue of Noland Arbaugh, who was paralyzed from the shoulders down after a 2016 diving accident. The surgery was reported to have gone well, with the patient able to go home a day after the procedure. In the weeks after the implantation, Arbaugh said he was able to use the chip to control various devices. “[Arbaugh] has used the Link to control his laptop from various positions, including while lying down in bed,” according to a Neuralink blog post discussing the trial progress. “He plays online computer games with friends (Chess, Civilization VI), browses the internet, live streams, and uses other applications on his MacBook, all by controlling a cursor with his mind.”

About a month after the surgery, it was reported that some of the device’s electrode-studded threads had started to retract out of position, resulting in fewer electrodes that could measure brain signals. Due to these complications, Arbaugh began losing functionality of the device. Neuralink said that it has since been able to restore the implant’s ability to monitor brain signals by making changes to its algorithm so that it is more sensitive.

“In the weeks following the surgery, a number of threads retracted from the brain, resulting in a net decrease in the number of effective electrodes,” the company blog post said. “This led to a reduction in BPS (Fig 04). In response to this change, we modified the recording algorithm to be more sensitive to neural population signals, improved the techniques to translate these signals into cursor movements, and enhanced the user interface. These refinements produced a rapid and sustained improvement in BPS, that has now superseded Noland’s initial performance.”

The potential for these complications in human subjects has been known about for years, according to a Reuters report. Animal testing the company had conducted ahead of its in-human trial approval showed that the wires might retract. However, Neuralink, according to the report, deemed the risk low enough to not merit redesign. FDA was also aware of the potential issue as it was shared with the agency as part of the application to begin human trials.

Now with the second patient, the company said that it intends to circumvent the issue by embedding some of the chip’s wires deeper in the brain, according to The Wall Street Journal. This, however, could lead to additional problems, according to Reuters. If anchored to the brain, the brain tissue could be damaged if the threads dislodge or if the company needs to remove the device.

Neuralink said it expects to implant the device in the second patient in June, and a total of 10 people in 2024. Additionally, it reported that more than 1,000 quadriplegics have signed up for its patient registry.

In addition to its focus on the implant’s cursor control performance, the company said it intends to extend its functionality to enable control of “robotic arms, wheelchairs, and other technologies that may help increase independence for people living with quadriplegia,” according to the Neuralink blog post.