Hello Dennis.

I don't think that it is published in detail.
However, generally, the more you are 'active' the more points (neurons) you will get.
The quickest and simplest way to gain points is to play the games on the home page - I think that accepting 'challenges' and setting goals produces more points - faster - though this is something I have not tried.
I find that working on the forum is more interesting (for me) but does not gain points so quickly.

You move up ranks ('newbie', member, advanced member) automatically - it seems to be based on time and activity.
If you are a member for a few months, but only visit the site once a week, it takes a long time to change. If you play games and post questions or replies or opinions on the forum every day, you will move up to 'advanced member' quite quickly.

Take a look at Goldman M's post here. She is no longer an admin, but her advice and answers are still very valid.