Very interesting article from Cornell University discussing the links between dopamine and our emotional state: "Dopamine linked to a personality trait and happiness"
A few interesting points: "One personality trait in humans is how sensitive and responsive we are to incentives and rewards," said Richard Depue, professor of human development and family studies and director of the Laboratory of Neurobiology of Personality and Emotion at Cornell. The higher the level of dopamine, or the more responsive the brain is to dopamine, the more likely a person is to be sensitive to incentives and rewards. "When our dopamine system is activated, we are more positive, excited and eager to go after goals or rewards, such as food, sex, money, education or professional achievements," Depue said. Lastly: In related research, Depue has shown that dopamine is strongly related to how well the prefrontal cortex holds information. "To hold in short-term memory a spatial map of the environment, for example, you must have the dopamine system activated; without it, you can't do this type of cognitive functioning," Depue concludes from his research in this area.