Amygdala

Functions
related to size of social groups

associated with fear and anxiety

Scientists discover anti-anxiety circuit in brain region considered the seat of fear

http://www.physorg.com/news/2011-03-scientists-anti-anxiety-circuit-brain-region.html

Ritalin Boosts Learning by Increasing Brain Plasticity

http://www.sciencedaily.com/releases/2010/03/100307215544.htm

source: http://en.wikipedia.org/wiki/Amygdala