What is a biological explanation for Introverts need for recharging?

The same thing that happens in extroverts brains. Just a different charging source. Extroverts draw energy from social interaction. It feeds their brains and makes them feel energized. Introverts lose energy in social settings. Mental fatigue sets in if you are interacting with people a lot. The introvert “recharges” by being alone, doing quiet things, not having to deal with others.

It seems it depends on how many receptors you have in the brain. We all have dopamine and acetylcholine receptors in our brains. If you have one more than the other than we are either wired for excitement and get charged by it or we get overwhelmed because we may have more acetylcholine receptors, so they need quiet and calm to think things over and center their mind.
I had to look this up. So it seems there us no way to change what most people believe is behavior. I don’t think you can change brain receptors. Seems most people have the same amount and they are the ones that most if us wouldn’t call an extrovert or introvert.