Introverts, on the other hand, are highly sensitive to dopamine. Too much dopamine and they feel overstimulated. Introverts use an entirely different neurotransmitter, acetylcholine, on their more dominant pathway. Acetylcholine is another important neurotransmitter connected to many vital functions in the brain body. It affects attention and learning (especially perceptual learning), influences the ability to sustain a calm, alert feeling and to utilize long-term memory, and activates voluntary movement. It stimulates a good feeling when thinking and feeling. Introverts require a limited range of not too much or too little dopamine, and a good level of acetylcholine, to leave them feeling calm and without depression or anxiety.
Then there's the stuff about thinking more than everybody else. These are the sort of thoughts people like to discourage you from having because, presumably, it means you are being arrogant. Unfortunately the evidence is rather high. I probably should look into this more. I'd like to minimize my discontent.
Of course, there are other people who should look into this more- the extroverts who get all the good jobs due to the fact they can charm the crap out of people. Especially the women in HR departments around the world- you'd think it would dawn on them they are tanking the company. I hope some of the people reading these books on introverts aren't introverts. The division of labor requires agreement, and part of that agreement is that people in the appropriate positions actually understand what people like me are good for.