It is said that Introverts have more sensitive dopamine system. They need less stimulation to feel the same "kick" than extroverts. This has benefits and it has downsides. Benefits are for example that introverts can really feel things strongly and notice every slight detail. Downside of this sensitive dopamine system is that if there is alot going on around you, like alot of people, it can drain introverts fast, and then they need to recharge in solitude to feel energized again.What is the difference in neurochemistry between those types? What unit of "energy" do these types gain when doing their preferred activity? ATP? Dopamine?