“The dopamine that nicotine releases goes to the prefrontal cortex of the brain,” explains Johnston. “That’s the pleasure center of the brain. It’s what people believe is responsible for the pleasure, the sense of well-being, associated with smoking, and that’s one of the reasons it’s so hard to quit. Nicotine also increases norepinephrine, and that’s the reason that when you try to quit smoking and you no longer get so much norepinephrine, you get agitation and irritability.
