What are the effects of social rejection on the brain? What are the effects of social rejection on the brain?

If the external circumstance can not change, how can the impact on the brain be reduced?

What is the average sensitivity to social rejection and are some not effect by it?

Any points in the right direction are helpful.

So far I have found only 1 study (Eisenberger et al., 2003) summarized as follows (but unable to make any conclusions):


  A ball is passed to a group of students except for one student, who
  does not know what the experiment is. When the ball is not passed to
  the "excluded" student, the brain of that excluded lights up in the
  same place as in physical pain.


References


Eisenberger, N. I., Lieberman, M. D., &amp; Williams, K. D. (2003). Does rejection hurt? An fMRI study of social exclusion. Science, 302(5643), 290-292.
I followed your info and found 2 research papers: 


Why Rejection Hurts?
(In case you want to skim through more papers, visit Papers from Social And Affective Neuroscience Laboratory. Naomi Eisenberger is the director of this Lab.)
Belongingness as a Core Personality Trait: How Social Exclusion Influences Social Functioning and Personality Expression


To help you access this paper promptly, I shared a pdf version here.



I read through the paper 1 and skimmed paper 2 in order to extract conclusions that are relevant to your question:

    "If the external circumstance can not change, 
     how can the impact on the brain be reduced?"



  From Why Rejection Hurts
  
  
  factors that increase or decrease one kind of pain should affect the other kind of pain in a similar manner.
  participants reported significantly less pain when holding their partner’s hand than when they held a stranger’s hand
  “If all this is true, does that mean that painkillers could reduce the pain of social rejection?” ... -- in fact the answer is yes.
  
  
  From Belongingness as a Core ...
  
  
  Acetaminophen(the active ingredient in Tylenol) Reduces Daily Hurt Feelings
  Tylenol Reduces Neural Activity Associated With Social Pain
  Acetaminophen Reduces Nonconscious Coping Responses
  Mindfulness interventions reduce the sting of rejection, thereby decreasing self-control impairments and aggressive outbursts.
  


About the second question, I only digged a little bit.

    "What is the average sensitivity to social rejection
    and are some not effect by it?"



  
  From a book named "Are You Ethical" by Steve Soto
  
  
  The following text does not directly answer the question, you could view it as a heuristic: When someone is less sensitive, she/he will be less affected by social rejection.
  
  
  "On the other hand, others take rejection as an indication that others don’t realize that what they have to offer is beneficial, it only amplifies the faith they have in themselves, and they persevere that much harder. It is never taken personally, or as an affront. This is “a low level of rejection sensitivity”. -- Karen Horney