PFC is a state of mind that is most suitable for learning and making decisions. It is named after the Prefrontal Cortex, which seems to be heavily involved in this state. It works when there is no threat (FFFF). It uses most of the time system 1, but in RPE can activate system 2.
PFC seems to be controlled in the vmPFC (as was written in a summary of an article in Haaretz (Hebrew))