The therapeutic effect of Ketamine (according to the psychiatric consensus anyway) works independently of the experience of being on Ketamine (in the sense that, it shouldn’t matter if you have some kind of incredible trip or were just knocked out completely - not that that would happen under normal circumstances - but the effect will occur regardless). But by ‘numbing’ I meant to contrast the effects of Ketamine (both in terms of the inner journey while taking it, but also the antidepressant effect afterwards) with more constrictive psychiatric drugs (anti-psychotics for example) which seem to exert beneficial effects precisely because they do numb people psychologically to the point there preoccupations don’t worry them so much anymore.
Neurogenisis happens all the time. If you run before work, start to feel happier at work, start doing your job better - that’s effectively ‘neurogenisis’ in the sense of creating new pathways. The reason I say it’s unclear how important this is to Ketamine is because pharma companies often claim their drugs work nowdays by neurogenesis, but it’s not necessarily accurate. My understanding is you could dose a patient with heroin and then do a brain scan showing neurogenesis, but that doesn’t necessarily give a good indication of its function or effects. It reminds me a bit of the old serotonin theory of depression/medication which they used to push and which is generally understood as a gross oversimplification nowdays