Hypothalamus

Hypothalamus is a division of the diencephalon Subserves three systems: Autonomic Nervous System Endocrine System Limbic System Hypothalamus helps to maintain homeostasis

Paraventricular nucleus Synthesizes ADH, Oxytocin and Corticotropin Releasing hormone Secretes Oxytocin Gives rise to supraopticohypophyseal track that projects neurons to the neurohypophysis (posterior pituitary) Regulates water balance Projects directly to the autonomic nuclei of the brain stem and all levels of the spinal cord Destruction leads to DIABETES INSIPIDUS

Supraoptic nucleus Synthesizes ADH and Oxytocin, similar to the paraventricular nucleus Secretes ADH

Anterior Nucleus Thermal regulation (dissipation of heat) Stimulates PARASYMPATHETIC NERVOUS SYSTEM Destruction of Anterior nucleus leads to HYPERTHERMIA

Preoptic Nucleus Regulates release of gonadotropic hormones from adenohypophysis (anterior pituitary) Contains sexually dimorphous nuclei, development of which depends on testosterone levels

Suprachiasmatic Nucleus Receives input from the retina Regulation of circadian rhythms

Dorsomedial Nucleus Stimulation leads to OBESITY and SAVAGE BEHAVIOUR

Posterior Nucleus Thermal Regulation (conservation and increased production of heat) Stimulates the SYMPATHETIC NERVOUS SYSTEM Lesions lead to Poikilothermia (inability to thermoregulate)

Lateral Nucleus Stimulation induces eating Lesions cause ANOREXIA and STARVATION

Mamillary Body Receives input from the hippocampal formation through the POSTCOMMISURAL FORNIX Projects to the anterior nucleus of the thalamus through the MAMILLOTHALAMIC TRACT (PEPEZ circuit) Lesion: Wernickes Encephalopathy, Thiamine or Vit B1 deficiency, alcoholism

Ventromedial Nucleus Satiety center Stimulation INHIBITS URGE TO EAT Stimulated by leptin B/L destruction leads to hyperphagia, obesity and savage behavior

Arcuate (infindibular) Nucleus Contains neurons that produce factors that stimulate or inhibit hypothalamic actions Contains neurons that produce dopamine (prolactin inhibiting factor) Nucleus gives rise to the TUBEROHYPOPHYSEAL TRACT which terminates in the hypophyseal portal system of the infindibulum (median eminence)