Whats the science behind erogenization of body zones/parts?

Is the whole body susceptible to become a stable erogenous zone? I have managed to make my nipples (male) extremely sensitive, but this isnt always the case with males, i had a hint of it before, but now its like touching the tip of my penis.

Cant be mere "conditioning" because for this to be the case the whole body should have the same amount of nerve receptors to give equal intense feelings in other parts that arent erogenous per se. Any studies on this?