Technically, we aren't mapping emotions. We are mapping the blood flow to the parts of the brain that are active when various emotions are experienced. From this we infer that neural transmissions are occurring there. But these neural transmissions are merely electrical currents, and electrical currents are not happy, sad, angry, compassionate, etc. However, since they happen in conjunction with these feelings, these currents are known as "neural correlates of consciousness", or NCC, by neuroscientists. There is correlation there, but not an identity; what emotions and consciousness are is still completely unknown from the point of view of neuroscience. Some people like to say that they are an epiphenomenon of brain activity, but there is no evidence or precedent for that; everything else that can be labeled "epiphenomena" can by scientifically tied back to its source using standard laws of physics. Not so for consciousness and its various aspects.
From a strictly scientific point of view, what consciousness and its various aspects are is completely unexplained at this point.