Dopamine euphoria
focusing on mdpv is a breeze, i agree. but what does it mean for euphoria to be learned?
Well, it's that "dopamine euphoria" is subtle and learned, IMO. Serotonin euphoria is obvious (empathogenic), norepinephrine is obvious (energy), opiate is obvious, etc.
Dopamine is deeply tied in to things like motivation, the sex drive, attention and focus, memory and learning, cognition, punishment and reward. Look for dopamine's subtle euphorias in these arenas... they have to be looked for and discovered, IMO. As an example, one of peevee's first and most famous has been in the area of pro-sexuality.
Another that I've personally found is how brilliantly clear my mind/memory can get on peevee, like a highly polished diamond refracting laser-light. That can be very pleasurable and creative.
From wikipedia: "Dopamine in the mesolimbic pathway increases general arousal and goal directed behaviors and decreases latent inhibition; all three effects increase the creative drive of idea generation".
^^ I mean, why do ya think these peevee threads are so big/numerous? Creative generation of ideas

. It's much more a thinker's drug rather than an "emoter's drug", eh?