The illustration shows telencephalon, brainstem, cerebellum in median section. Projected on a female head in front of a white background. The brain is the part of the central nervous system (CNS) of vertebrates that is in the head. The vertebral brain is a temporary destination in the evolution of the nervous system, since it processes highly centralized sensory stimuli and coordinates complex behavior. It is the main integration area for all information necessary for survival an organism can process.