Mayberg’s 2005 paper, published in Neuron, amazed her colleagues. To get such results in patients this sick was stunning. Tom Insel, then the director of the U.S. National Institute of Mental Health, called it “a new way of understanding depression.” The attention expanded into the public realm in 2006—a story I wrote about Mayberg’s work in The New York Times Magazine that April; a CBS News 60 Minutes segment that September. Her phone rang ever more often with calls from reporters who wanted to interview her, universities and institutions that wanted her to come lecture—and scores of hopelessly depressed people, or their family members, who’d seen the press and wanted the treatment. Mayberg was on fire.

It wasn’t long before St. Jude Medical, the device company that made the neurostimulators Mayberg used, decided to run a clinical trial to seek U.S. Food and Drug Administration (FDA) approval for the treatment. There were, of course, risks to moving ahead so soon. Mayberg and her colleagues, for instance, had been using the implants with more people and were seeing hints of variables that might affect the treatment’s power—differences in the quality of the patient’s depression, in how the surgeons sited the device—that, if explored, might make the treatment even more effective. You could, of course, wait forever—you could always find out more—but at some point you had to forge ahead. And the thing was working. People were all but rising from the dead.

So in 2008, after much discussion, she signed on as one of more than two dozen researchers from all over North America who would serve as consultants and investigators to help design and execute the trial. As is usual in trials of this size, with multiple treatment centers, the sponsor—St. Jude, in this case—would actually administer it. Many of the researchers had done trials before; Mayberg had not. And no one researcher, including Mayberg, could hope to direct everything. She hoped to do what she could to ensure the trial was rigorous and the patients treated well.

St. Jude branded the trial the Broaden study—for Brodmann Area 25 Deep Brain Neuromodulation. The plan was to have 20 neurosurgery centers implant St. Jude’s DBS devices in 200 people with treatment-resistant depression, then turn on the devices in two-thirds of them. In the other third—the control group—they’d leave the devices inactive for six months before activating them. No one with patient contact would know which patients were which. Then they’d follow all 200 patients for two years after implantation to see how the two groups fared. Would the active-implant group do better than the control group? Would they do as well as Mayberg’s own patients?

By 2017, when it was over—long, long after it should have been—Broaden would reveal not only the answers to those questions, but also deep tensions and confusion about the limits of a clinical trial, the nature of research, and the difference between the two.