Current and former Neuralink employees told Reuters that the FDA’s major safety concerns involved the device’s lithium battery, the potential for the implant’s tiny wires to migrate to other areas of the brain, and questions over whether and how the device can be removed without damaging brain tissue. The agency outlined dozens of issues that the company must address before human testing, a critical milestone on the path to final product approval.
Neuralink has reportedly been working to address the FDA’s concerns, but current staffers told Reuters that they were skeptical that the company could resolve the matters within a short period of time. Musk told his employees in November that he anticipated Neuralink would be able to secure FDA approval for human trials sometime in the spring.
Neuralink has not disclosed details of its trial application, the FDA’s rejection, or the extent of the agency’s concerns. As a private company, it is not required to disclose such regulatory interactions to investors.
Musk and other Neuralink officials did not respond to requests for comment on the company’s device or its dealings with the FDA. The agency declined to comment on Neuralink, citing laws keeping commercial information private.
In December, it was reported that Neuralink was being investigated by the US Department of Agriculture’s Inspector General for alleged violations of animal welfare laws. The federal probe was opened in the latter half of last year at the request of a federal prosecutor.
The investigation came at a time of growing employee dissent about Neuralink’s animal testing, including complaints that pressure from Musk to accelerate development has resulted in botched experiments, according to Reuters. The company has killed about 1,500 animals, including more than 280 sheep, pigs, and monkeys, following experiments since 2018, according to records reviewed by Reuters and sources with direct knowledge of the company’s animal-testing operations.