Haven’t done a Randomness in awhile.  This one is courtesy of Syeda in the Beeman lab:

Facebook Friend Count Linked to Brain Density

(mashable.com reporting from Proceedings of the Royal Academy of Sciences)

The write-up even nicely opens with the correlation/causation problem — do brain differences cause more friends or do more friends cause brain differences?  The areas of gray matter density correlating with number of friends are a collection of temporal lobe regions, mostly non-MTL.  Intriguing but not trivial to make sense of.  I headed to google scholar to see if there was any other work in this area and found a study on Facebook use in TBI patients (http://informahealthcare.com/doi/abs/10.3109/02699052.2011.613086).  Interestingly, they also approach Facebook/social networking as a positive thing and with these patients find what we’d expect: some barriers to use related to level of impairment and prior familiarity.