Appreciation of the structure of the central nervous system (CNS) as a part of the larger human system is an important concept to consider in both clinical and research practice. Understanding of the development, structure, and function allows for further conceptualization of the mechanisms and localization of damage that can occur and result in presentation of intellectual and developmental disorders. This entry describes the basic development of the CNS structure, as well as the communication involved both within and between areas that regulate aspects of cognitive, behavioral, and emotional functioning.