The human prefrontal cortex may not be special in terms of its size relative to other primates, but it is still a pretty special.
http://blogs.scientificamerican.com/beautiful-minds/2013/05/16/gorillas-agree-human-frontal-cortex-is-nothing-special/?utm_source=feedly
Want to know what it does? Here’s a start:
Miller, E.K. and Cohen, J.D. (2001) An integrative theory of prefrontal cortex function. Annual Review of Neuroscience, 24:167-202. Designated a Current Classic by Thomson Scientific as among the most cited papers in Neuroscience and Behavior. View PDF »