"Kundalini" experiences during meditation Can anyone advise on experiences of "kundalini" (energy rushing up the spine and out the crown of the head) during meditation?  I have experienced this for years and am wondering if it has an understanding/meaning in the Theravada tradition.  The energy has a physical effect (jolting the body) and a mental one (like temporarily cleaning out the conscious mind).  Thank you greatly.
I've experienced this myself on a number of occasions though I never heard it called kundalini. Sometimes the experience has been exactly as you describe it. Sometimes it's a tingling feeling all over the body. Sometimes it feels like electric jolts. Sometimes the jolts manifest in physical movement.

I was advised that this was probably a manifestation of piti (rapture). This would be in the context of the rupa-jhana factors going from 


applied thought (vitakka) 
sustained thought (vicāra)
joy/rapture/happiness (pīti) 
happiness/pleasure/bliss (sukha)
equanimity (upekkhā)
one-pointedness (ekaggatā)


So you could expect this to be proceeded by strengthening concentration and perhaps develop into a calmer more pleasurable state (sukka). Here is a further breakdown of piti which again feels familiar to me. Yours might fit into the last two classification - exalting and fulfilling rapture.

From conversations I had with other people the exact manifestations of these very much depend on the type of person. I'm more the anxious, type A type of person so I feel a lot of energy. I often feel it trapped in me then it comes out in great surges. Other people never feel this.

I think the important thing with these kind of experiences is not to get attached to them and not to pursue them. They are as they are and they come and go. In the experience themselves there is no insight nor is there lasting benefit. Like everything these things are ultimately impermanent and unsatisfactory.