Under the supervision of a medical team, New Scientist's Graham Lawton took a dose of MDMA and then lay in an fMRI machine. You know. For science.
Lawton was a participant in a double blind, controlled, clinical study — meaning that he didn't actually know whether he was going to be taking ecstasy or Vitamin C when he went in ... and neither did the scientists who gave him the pill. That's because the researchers want to know whether and what differences show up between the functioning of brain under the influence of MDMA and one that's sober. Not knowing which type of brain they're looking at helps them avoid their own biases, or tendencies to "spot" a difference that doesn't actually exist simply because of what they expect a high brain (or a sober one) to be doing. Only after they've made their observations do the scientists find out which brains were which.
The goal is to document was ecstasy does to the brain. Astoundingly, writes Lawton, nobody has ever done that before. And it matters, because some people think that drugs like ecstasy could be useful in helping people deal with psychological stress disorders. Not that the drugs would cure the disorder, per se, but that ecstasy could help people talk about their bad experiences more easily. Right now, there's not a lot of evidence supporting that idea, beyond some anecdotes. Studies like this help scientists figure out whether the anecdotes are pointing at a useful treatment tool, or just relating some personal experiences.