Elon Musk’s brain implant company Neuralink said on Wednesday it now has 21 total participants enrolled in trials worldwide, as it completes two years since it officially began testing on humans.

This marks an increase from the 12 people the company in September said had received its chips and were using them to control digital and physical tools through thought.

The implant is designed to help people with conditions such as a spinal cord injury. The first patient has used it to play video games, browse the internet, post on social media and move a cursor on a laptop.

“A primary aim of our expanding clinical trials is to better understand these variations and improve both our hardware and the overall procedure for every participant,” the company said in a statement.

Neuralink began human trials of its brain implant in 2024 after addressing safety concerns raised by the U.S. Food and Drug Administration, which had initially rejected its application in 2022.

The company said it is working closely with regulatory bodies and hospital sites to deliver improved devices to participants and maintain its current record of zero serious device-related adverse events.

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(Reporting by Christy Santhosh in Bengaluru; Editing by Alan Barona)