The United States Food and Drug Administration (FDA) did not allow Elon Musk and his brain-computer interface company Neuralink to test their brain chip implants in humans, Reuters reported.

While the sources declined to give Reuters the FDA's written denial, explaining it was a confidential document, they described the features of the devices that caused the regulator's concerns.

Neuralink Co-Founder Max Hodak Left the Startup
Co-founder of the Neuralink startup, Max Hodak, who worked with Elon Musk on brain implants, has left the company. He did not publicly announce the reason for leaving the startup.

In explaining its decision, the FDA outlined dozens of safety issues the company must resolve before moving forward.

The agency's major safety concerns involve the battery system of the device, the potential that the tiny wires of the implant could migrate to non-targeted areas of the brain, and questions over how and if the device can be removed without damaging the human brain.

Elon Musk’s Neuralink Raises $205 Million From Investors
The company attracted a record $205 million in investments from Google Ventures, the Dubai fund Vy Capital and several other investors, including DFJ Growth, Valor Equity Partners, Craft Ventures, Founders Fund, and Gigafund.

As noted by Reuters, the FDA rejection does not mean that the company's development is doomed and that it will not be able to obtain permission to conduct human trials. However, it will be much more difficult to do so since this decision by the regulator indicates that it has serious concerns.

In late 2022, Elon Musk announced that the company would receive FDA approval and begin human trials within six months – that is, by the spring of this year.