Most areas of the brain are rather homogenous. They've done experiments rewiring inputs going to the visual cortex to the auditive cortex in rodents and they could see. Further, artificial neural nets demonstrate that extremely simple repetitive structures can implement a vast function space simply by training them by stochastic gradient descent. The most complex structures in the brain may be hardwired social behaviors, including facial expression and recognition, but these may not be necessary for the intelligence part as individuals strongly impaired in hardwired social behavior (autists) are sometimes capable of complex thought.