First and foremost, let me just say this: Sorry if I do not make sense at the moment, Fnord - I'm still "coming to" from a particularily revealing meditation. ...You know the kind, I'm sure - where you're left going "Ahh, so that's what I was missing". Anyways...
Concerning DMT trips: I wouldn't know, Fnord - I avoid using drugs of any sort because of the lack of control they represent; you are at their mercy, to a degree and this most certainly is not what I'm looking for in meditation. Infact, one might wonder: is this even "anathema" to meditation?
...Nevertheless the law is: "do as thou wilt", correct?
As per the flashing lights: What I describe in this isn't just one type/kind of flashing light, but rather a whole host of phenomenon understand; tiny balls of light (sparks?), shifting patterns, colored explosions akin to fireworks, ...and what appears to be, slow-growing spheres of light which can even cover the whole field of perception in a dazzling light. This often happens while concentrating upon some object (form), often beginning with the object (form) glowing until it becomes a dazzling light and the form is lost...but not the concentration? Honestly, I hardly pay attention to all the visual phenonmenon - most of it can be chalked up to shitty concentration, after all. Rather it's the other 10% of the phenomenon that gets one thinking "what the hell was that"?! The only real connection here is that all of this seems to happen in the location of the ajna chakram (lower down the head), as opposed to the sahasrara (as in the case with the Light described above).
That said: No, I do not get the sensation of electric shocks, during any phenomenon, although there are certain sensations I've grown accustomed to such as the feeling - of what I might describe - water pouring on the crown of the head and/or certain experiences I suppose we could call "mental orgasms" - the intense sensations of an orgasm which are the providence of the head alone. I find, through my own experiments, that these sorts of sensations can be reproduced via a manipulation of the emotions; ie: these sensations are (theoretically) manifestations of activity within/of the astral body.
...Have I answered your questions, Fnord? Hopefully!
Thanks for your time,
QaZsE - Fr. T.E.U.