Are there detectable differences in brain activity when thinking about people of different degrees of closeness? Once upon a time I read an article (or perhaps study/paper - I don't know) regarding different brain activity when referring to / thinking about different people: 


You 
Your close people, like family 
Your not-so-close people, like friends or the keeper of the shop you usually go to 
People you don't know like, say, politicians and celebrities


There is a chance that I read just crap from the internet (again) [Edit: I struggled trying to find the article on google but couldn't], but I'd like to know if there is any reliable source for that claim (a peer-reviewed-and-not-yet-dismissed paper, say).

Is there any reliable source (peer-reviewed &amp; non-dismissed research paper - you all understand this matter better than me) regarding that topic?
This domain is extensively explored as a "self-referential processing"
The largest difference between self vs. non-self is higher activation for self-relatad activation of medial posterior and frontal regions 
(e.g., https://davidcjohnson.files.wordpress.com/2011/04/self-ref-vs-valence.png?w=694&amp;zoom=2)
Those two regions are part of the Default Mode Network.

One of the most prominent researchers is Georg Northoff: 

https://scholar.google.ca/citations?user=-w-9zOQAAAAJ&amp;hl=en
You can check his reviews and found references to many additional studies.