The Hypothalamus as a Major Integrating Center

Abstract

The “constancy of the internal milieu,” as described by Claude Bernard in 1859, is essential for the survival of any warm-blooded animal, and its maintenance requires strict control over behavioral, autonomic, and endocrine responses to the environment. The hypothalamus has clearly evolved as the major integrative center for regulating all of these homeostatic control systems. The location of the hypothalamus—superior to the hypophysis, and adjacent to subcortical “limbic” structures—suggests this role, as it is uniquely positioned to both send and receive endocrine signals, as well as neural signals from sensory organs, memory centers, and autonomic circuitries. Incoming information is registered, analyzed, and integrated in hypothalamic neurons. On the basis of these calculations, the hypothalamus effects the changes, if needed, in hormone secretions, behavioral state, and autonomic activity. The hypothalamus is thus responsible for monitoring the internal and external environment and coordinating adaptive physiological responses among several systems.