ABSTRACT
This chapter reviews the complex structure of the brain with an emphasis on understanding the brain's ability to connect different structures through a maturation process based on psychological processes. The brainstem is the structure closest to the spinal cord; it controls vital functions, including the cardio-vascular system with heart rate and blood pressure and breathing and swallowing reflexes. Higher levels in the hierarchical structure of the brain have more complex polymodal areas. The polymodal regions are also referred to as the association cortex, or convergence zones, and they are the most complex system in the brain. The brainstem also contains an activation system that regulates the activation level of the cerebrum, arousal and consciousness. The brain constantly has to inhibit vast amounts of neural activity in order to function efficiently. The prefrontal cortex consists mainly of an association cortex that processes information from other neural systems and "directs" motor activity.
