Elon Musk’s brain-implant company Neuralink on Thursday said the U.S. Food and Drug Administration (FDA) had given the green light to its first-in-human clinical trial, a critical milestone after earlier struggles to gain approval.

The FDA nod “represents an important first step that will one day allow our technology to help many people,” Neuralink said in a tweet. It did not elaborate on the aims of the study, saying only that it was not recruiting yet and more details would be available soon.

Neuralink and the FDA did not immediately respond to Reuters requests for comment.

Musk envisions brain implants could cure a range of conditions including obesity, autism, depression and schizophrenia as well as enabling web browsing and telepathy. He made headlines late last year when he said he was so confident in the devices’ safety that he would be willing to implant them in his children.

On at least four occasions since 2019, Musk predicted Neuralink would begin human trials. But the company only sought FDA approval in early 2022 and the agency rejected the application, seven current and former employees told Reuters in March.

The FDA had pointed out several concerns to Neuralink that needed to be addressed before sanctioning human trials, according to the employees. Major issues involved the lithium battery of the device, the possibility of the implant’s wires migrating within the brain, and the challenge of safely extracting the device without damaging brain tissue.

Neuralink, founded in 2016, has been the subject of several federal probes.

In May, U.S. lawmakers urged regulators to investigate whether the makeup of a panel overseeing animal testing at Neuralink contributed to botched and rushed experiments.

The Department of Transportation is separately probing whether Neuralink illegally transported dangerous pathogens on chips removed from monkey brains without proper containment measures.

Neuralink is also under investigation by the U.S. Department of Agriculture’s Office of Inspector General for potential animal-welfare violations. This probe has also been looking at the USDA’s oversight of Neuralink.

Neuralink has not responded to requests for comment on the probes.

(Reporting by Akriti Sharma in Bengaluru; Editing by Anil D’Silva, Lincoln Feast and Edwina Gibbs)