Elon Musk is renowned for his Tesla cars and SpaceX rockets and plans to colonize Mars. But his brain-chip startup Neuralink has taken a significant step toward the billionaire’s far more ambitious goal of one-day enabling people to control computers with their minds. The company says it’s performed its first implant on a human, and the person is recovering well. The announcement came post-Monday on X, the company’s social media-like platform that Musk owns.

The company says the trial, called “Prime,” is recruiting people with paralysis caused by cervical spinal cord injury or amyotrophic lateral sclerosis (ALS). Those who enroll in the study will receive an implant to use external devices to move. The implant records neural spikes, which are electrical signals that help neurons communicate with each other. Then, a system converts those signals into a type of movement. In the long term, the technology could let blind people see and give those with a severed spinal cord full-body functionality.

Neuralink, founded in 2017, has spent years testing the device on monkeys. Some of those tests raised alarms among animal rights activists who objected to the company’s use of animals for the experiment. But the company insisted that no monkey has died, and it only used “terminal” monkeys to minimize the risk to healthy ones.

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At a recruiting event last year, Musk predicted that the company would be able to begin human trials within months. But according to a recent Reuters report, that didn’t happen. The FDA told the company that it must follow more stringent safety guidelines to ensure that parts of the implant don’t migrate into other brain areas and cause damage when removed.

That’s not the only obstacle that Neuralink faces. The company’s staff say it’s undergoing scrutiny from the Securities and Exchange Commission for alleged securities fraud over its failure to disclose that it was having trouble getting FDA approval for the implant. The SEC is also looking into the company’s careless handling of its gruesome monkey experiments, which led to some of the animals’ deaths.

A company spokesman declined to comment on the SEC probe or on hiring new employees by the Neuralink team, which includes several former members of the biotech firm Blackrock Neurotech, which was shut down in a corruption scandal in 2021. Earlier this week, Neuralink announced that it had gained approval from the Food and Drug Administration to start the clinical trial in humans. That approval is likely the most significant hurdle the company will face on its journey to a future where people can control their computers with their minds. Neuralink is one of a handful of companies developing neural interfaces to connect the human mind with technology.