Elon Musk has made plenty of claims about Neuralink, his brain-machine interface company. On Twitter and on podcasts, the billionaire has touted abilities that sound nothing short of miraculous: easing depression, helping with obsessive compulsive disorder and treating traumatic brain injuries.

Now, Neuralink, whose work has largely been shrouded in secrecy, is set to give a public “progress update” on Friday.

In the run-up to the big reveal, Musk has allowed some glimpses at the company’s technology. An early look came a year ago, when the Neuralink team showed off tiny electrodes on thin, flexible probes they said would be able to penetrate brain tissue with minimal damage, and ultimately help restore brain function to people with traumatic brain injuries. The team has already been placing them in rats and primates.

Will the devices actually be able to achieve the breakthroughs Musk says they can? Here’s a rundown of what we know so far about Musk’s startup—the most recent claims, the technology, and what neuroscientists say is actually possible.

Claim: Neuralink will soon be able to implant its technology in humans

On May 7, Musk appeared on the popular podcast, the Joe Rogan Experience, and made a distinctive claim about Neuralink: The startup would “be able to implant a neural link in less than a year in a person, I think.” The prediction is not actually as groundbreaking as it might sound. Musk was describing a procedure that happens fairly routinely to treat conditions such as epilepsy and Parkinson’s, despite potentially fatal risks such as brain hemorrhages.

Justin Sanchez, who helped fund research done by Neuralink scientists when he ran the biological technologies office at the Defense Advanced Research Projects Agency, estimates that about 200,000 people globally have some sort of neurotechnology implanted in their brain. In fact, the technology is so well developed at this point that the Battelle Memorial Institute, where Sanchez is a fellow, has developed a neurotechnology-based non-implanted device aimed at nothing more grandiose than helping people improve their golf swings.

The other important element of Musk’s statement was that Neuralink is on track for human trials by next year. To test so quickly in humans, the company would need to get an exemption from the normal multi-year regulatory process from the Food and Drug Administration. That may be possible—other brain implants have received exemptions. But Neuralink’s device could face additional challenges.

A report in health news site Stat News this week detailed internal tensions at Neuralink, citing former employees who said the company culture could be chaotic and that it quickly cycled through scientific talent. According to two anonymous former employees, it had explored possibly by passing the U.S. regulatory process by pursuing human trials in China or Russia.

Claim: Neuralink devices will be able to treat addiction and depression

On July 10, Musk took to Twitter with another notable statement. A Twitter user asked Musk if Neuralink could be used to retrain the part of the brain that causes addiction and depression. Musk replied, “For sure. This is both great & terrifying.”

Neuroscientists agree that placing electrodes in the brain could help mitigate those conditions. In fact, researchers beyond Neuralink are working on it now, including Alik Widge, a psychiatrist and biomedical engineer at the University of Minnesota. The treatment involves applying electrodes to a spot in the brain called the internal capsule, and works by stimulating connections to the prefrontal cortex to improve cognitive functions such as perception and judgment. About 200 patients worldwide have tried the technique for depression, Widge said.

In several countries opioid addicts have had electrodes implanted into the areas of the brain that control addiction. That includes the U.S., where a West Virginia man underwent the procedure late last year at WVU Rockefeller Neuroscience Institute. He has abstained from opioids since, a spokeswoman said. A second opioid patient underwent the same surgery earlier this month.

While there are hurdles to wide adoption, there is no reason Neuralink couldn’t push into these areas in the future. In a 2018 review of studies of deep brain stimulation and its effects on depression, scientists said the results “showed promise” but the technique remained experimental. “The psychiatrists I talk with say that they want to see much stronger efficacy data,” Widge said.