Elon Musk’s startup Neuralink revealed that it experienced a problem with its brain implant after the device was installed in its initial participant, 29-year-old quadriplegic Noland Arbaugh.
After the Jan. 28 procedure, Musk was quick to announce on X that Arbaugh was “recovering well” and that “initial results show promising neuron spike detection.” But just weeks later, the company said Wednesday, the device started to malfunction.
Cofounded by Musk, Neuralink is one of several companies developing a brain-computer interface, a system that provides a direct link from the brain to an external device. Neuralink’s technology is designed to decode intended movement signals from the brain to allow paralyzed individuals to move a cursor or type on a keyboard with just their thoughts.
Neuralink’s unique design may have contributed to the device’s mechanical issues. The company’s implant consists of a coin-sized puck that sits in the skull. It holds a battery, processing chip, and other electronics needed to power the system. Attached to this puck are 64 flexible “threads” thinner than a human hair, each containing 16 electrodes. The threads are meant to extend into the brain tissue to collect signals from groups of neurons. But, according to Neuralink, some of those threads didn’t stay in place.
“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,” according to a blog post published by Neuralink. This led to a decline in the rate of data transfer, measured in bits-per-second. A higher bits-per-second value indicates better cursor control.
The blog post doesn’t say how many threads have been pulled out of the brain or how many are still in place. “Suffice to say, that’s not supposed to happen,” says Matt Angle, CEO of Paradromics, an Austin-based company that is also developing a wireless brain implant to help paralyzed people communicate.
Neuralink didn’t offer an explanation as to why or how the threads came out, and the company did not immediately respond to a request for comment from WIRED. However, the brain naturally moves within the skull, and it’s possible that some of the Neuralink threads were pulled out by that movement.
Neuralink and Musk have touted the advantages of its device over the earlier Utah array, a mainstay of brain-computer interface research since the late 1980s. A rigid square, the Utah array contains a bed of 96 tiny shanks, each with an electrode at the tip for recording. Its shanks penetrate the tissue. A major limitation is that it’s not wireless and has to be connected to an external device with a cable.
By contrast, Neuralink’s implant is wireless and has a total of 1,024 electrodes. More electrodes means more data can be collected from the brain—if all those electrodes remain intact.
“Neuralink designed a very novel neural interface,” says Riki Banerjee, chief technology officer at Synchron, a New York company that is currently testing a brain-computer interface in people with paralysis. “They’re learning and that is part of the process.”