First Neuralink patient sees some implanted electrodes lose connection to brain

About 100 days after implanting its first human participant with its brain-computer interface chip, Neuralink reported that some of the hair-thin connecting wires laced into the tissue have stopped reporting back data.

“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 said in a blog update tracking the experience of 29-year-old Noland Arbaugh—a quadriplegic patient who previously demonstrated on video using the chip to operate his laptop, play computer games of chess and control his music player.

According to the company, the lost electrodes caused a drop in the peak data rate of the brain chip—meaning it was recording fewer analog neural signals and translating them into the digital bits-per-second used to accurately operate Arbaugh’s computer cursor. 

Neuralink N1 chip
An illustration of the N1 implant and electrode threads (Neuralink)

However, Neuralink said it was able to tweak its processing algorithms and make the system more sensitive to mouse movement commands, ultimately improving its performance beyond the earliest days of the study. 

The N1 implant includes 1,024 electrodes distributed among 64 threads. The company’s blog post did not discuss whether the retraction of the electrodes was related to the body’s response to the hardware nor whether it represented any dislodgement of the implant’s parts or posed any health risks.

“Our current work is focused on pushing cursor control performance to the same level as that of able-bodied individuals, and on expanding functionality to include text entry,” the company wrote, adding that in the future the chip may also help people with paralysis control robotic arms or wheelchairs.

Neuralink said Arbaugh typically activates the chip for eight hours of weekday research sessions, and on weekends his recreational use can exceed 10 hours per day. Previously, in order to interact with a computer tablet, he had to rely upon a stylus held in his mouth.

“I thought that the mouth stick was a lot better than BCI a month ago, when we compared them I saw that BCI was just as good if not better and it's still improving; the games I can play now are leaps and bounds better than previous ones. I’m beating my friends in games that as a quadriplegic I should not be beating them in,” the company quoted Arbaugh as saying. “It's given me the ability to do things on my own again without needing my family at all hours of the day and night.”