To what extend flow relate to the enlightenment state?
Yeah. If fMRIs keep up in this area I think there is going to be lots of room across traditions and secularists (?) to discuss states of being based on neurological profiles***.
Then there is a flow state that I think comes uniquely with speed/accelerated motion
and personal control (holding onto bik for example): such as what he's describing in mountain biking, what Ayrton Senna described in racing, what people feel in doing an activity to the point they are not thinking about it, nor anything else. Their mind is synced with the activity.
And this flow is not necessarily correlated to mental states of complete equanimity (which has flowish properties but lacks personal agency in my view-- but may in fact be just like the holding on to a bike more as a "Wow, this". I'm considering this now...) or may look very different on increasingly refined neurological measures...
More to your point, of levels of enlightenment experience: are there common signatures there between occasionally-released persons and always-released persons and under what conditions is that tested (e.g, the startle response).
To look five or ten years out with more of this research, one could kind of look at a teacher's life, environmental conditions, quality of being, and then very precisely train neurologically in that tradition--- or under that teacher's neurological profile (and will neurological mimicry mean having the same experience? Doubt it, but I don't know.
***This area is already known to be a limited in metric in terms of does a brain "on violence" have unique signatures, and thus far many non-violent people can be show to have similar neurological profiles to persons convicted of violent crime. So I am just containing the scope of some of my own thoughts above, here.