I have been considering functions as being linked to the drugs we all make and take-- neurotransmitters! I only have a few right now, as I know very little about the brain so far. Perhaps brain regions as well.
Si- Serotonin. The chemical linked to stabilized moods of comfort and happiness. Also perhaps a link to the hippocampus which creates (but doesn't store) memories and sequences. I wonder if Si-Fi users use their amygdala a lot, which forms, sorts and understands memories based on the emotion associated with them. It creates a timeline of feelings basically. There aren't a ton of drugs that people take just to boost serotonin other than antidepressants.
Se-Dopamine. The chemical linked to sharp inclines of happiness, like that linked with winning, sex (men mostly, women use different neurotrasmitters) and good food. What we developed to as a mechanism to give us positive feedback and a reward based on interacting with the environment in a positive way for our survival. If I have to link this to a drug for the sake of this thread, pretty much the majority of hard drugs, like crack.
Fe- Oxytocin and mirror neurons! Oxytocin is linked to feelings of maternity and was evolved for breastfeeding, but it is also released whenever we feel a sense of unity. The drug ecstacy is pretty much just a pure shot of oxytocin with a few other feel-good chemicals. In terms of brain structures, mirror neurons are cells that activate when we see another person doing or feeling something. It recreates the feeling in us and recreates the action. Heavily linked to empathy.