Four U.S. lawmakers have asked the Securities and Exchange Commission to investigate whether Elon Musk committed securities fraud by allegedly misleading investors about the safety of a brain implant being developed by the billionaire’s firm Neuralink, according to a letter to the regulator. The request for an inquiry came from Democratic House Reps. Earl Blumenauer of Oregon, Jim McGovern of Massachusetts, and Barbara Lee and Tony Cardenas of California, according to the letter sent to the SEC on Tuesday and reviewed by Reuters. Scrutiny over Neuralink's handling of safety protocols comes as the company prepares to test the brain implant in humans for the first time, a critical milestone for the startup's ambitions to help patients overcome paralysis and a host of neurological conditions.