A report from Reuters on Wednesday, May 15, found that Elon Musk’s company, Neuralink, knew about the possibility of tiny wires coming loose from its experimental brain implant device years before the first human patient experienced the issue. The company became aware of the issues with the device, which gives paralyzed patients the ability to operate digital devices with the power of their minds, during testing on animals.

The findings were ahead of the U.S. Food and Drug Administration’s approval last year. In 2022, the FDA initially rejected Neuralink’s application for human trials after safety concerns were raised about the wire threads following Neuralink’s animal testining. However, after further testing, the FDA granted approval in 2023.

When reached for comment on the new report, the FDA said that it is continuing to monitor the safety of patients taking part in the Neuralink study.

According to Reuters sources, the company knew from the animal testing that the threads in the device could retract, removing sensitive electrodes that decode brain signals. The problem could result in fewer electrodes measuring brain signals, causing the device to experience performance issues.

However, Neuralink didn’t find the problem to be great enough to warrant a complete redesign. Instead the company said it found a work-around for the first human patient, Noland Arbaugh, who was paralyzed from the shoulders down after a diving accident in 2016. The company reported it changed algorithms to improve the issue.

The wires attached to the device are thinner than a human hair, which aids in seamless removal of the implant and more ease in updating the device. According to the company, if larger wires were used it would result in the threads being anchored to the brain, creating an even greater danger to the patient. Larger wires being removed could lead to damage to brain tissue.

Arbaugh’s brain implant has 64 threads, some of which retracted. However, Neuralink did not disclose how many wires did become loose.

Arbaugh’s issues with the threads reportedly came weeks after his surgical procedure in January. Neuralink told The Wall Street Journal the retracted wires resulted in a reduction in bits-per-second, a measure of speed and accuracy for the patient’s ability to move computer cursor with his mind.

Neuralink did not disclose if there were any physical side effects from Arbaugh. In March, the company released a video showing Arbaugh playing video games with the power of his mind. He can also reportedly browse the internet and use a computer mouse with the help of the implant.

Neuralink has yet to respond to the latest report on problems with the threads. However, the company has revealed it plans on implanting the experimental device into 10 more human patients this year.