Well, if I ever can actually find a way to get a copy of my earlier brain scans, maybe we'd find something out (I was a study for a while -- yay for being a ginny pig!). Not really by consent, but that's what happens when you're locked up in a mental institution, they try all kinds of experiments on you. Brain scans, different drugs, electro shock therapy, more scans. I've lived a wonderful fairy tale life.
On a more serious note, it would be interesting to see if there are pre HRT differences or not.