Recently, emotions have been linked to monoamine neurotransmitters ("new three-dimensional model"), which proposed that there are three core neurotransmitters that mediate emotions. These neurotransmitters, norepinephrine, serotonin, and dopamine, work together to form different emotions. The serotonin system (5-HT) is related to punishment (sadness/disgust), the dopamine system (DA) regulates reward (feelings of joy/happiness), and noradrenaline (NE) regulates fear/anger as well as the "fight or flight" response.