scientific data for tasering pain level?

In GD there’s a thread about tasering.

However not having been tasered I don’t know how bad it hurts. I was wondering if there’s any scientific studies on physiological responses tasering compared to the other things that hurt?
I guess the question could be broken down in to what does the body do in pain? Do certain parts of the brain light up with activity? Are there pain hormones the body makes? Adrenaline for example seems like it would be one response to pain.

If so what painful events produce the same level of reaction as a tasering?

Various Googling suggests that while being tazered is painful, the pain is ancillary to the primary purpose, which is to produce involuntary muscle contraction. It is this, and not the pain, that incapacitates the tazeree.