The ever-excellent Neurocritic has an interesting post looking at "lesion studies" of depression. As he notes, he was hoping for real lesions, from people who'd had actual psychosurgery, but had to settle for a simulation study that used MRIs. The study, (Schoene-Bake et al., 2010) looked at the different brain areas affected by four different areas targeted in psychosurgeries meant to treat depression. According to the study, these four approaches overlapped in spots. And as the study put it, the
"convergence of these shared connectivities may derive from the superolateral branch of the medial forebrain bundle (MFB), a structure that connects these frontal areas to the origin of the mesolimbic dopaminergic ‘reward' system in the midbrain ventral tegmental area [VTA]. Thus, all four surgical anti-depressant approaches may be promoting positive affect by converging influences onto the MFB."
As Neurocritic notes, this finding overlaps heavily with experimental work in which Emory neurologist Helen Mayberg is targeting one particular connection along the MFB - an area called Area 25. Since I wrote on Mayberg's study at length in the Times Magazine a few years ago, and then more briefly in a followup at Scientific American, I find this quite intriguing: Mayberg's rigorous approach, in which two decades of work converged on Area 25, led her to an area that had been part of broader, less specific targets in earlier, cruder efforts, but which seems to be a more successful target.
Read more: Depression's wiring diagram