FUNCTIONAL NEUROANATOMY AND NEUROPATHOLOGY OF THE HUMAN HYPOTHALAMUS

The human hypothalamus is involved in a wide range of functions in the developing, adult and aging subject and is responsible for a large nu mber of symptoms of neuroendocrine, neurological and psychiatric disea ses. In the present review some prominent hypothalamic nuclei are disc ussed in relation to normal development, sexual differentiation, aging and a number of neuropathological conditions. The suprachiasmatic nuc leus, the clock of the brain, shows seasonal and circadian variations in its vasopressin neurons. During normal aging, but even more so in A lzheimer's disease, the number of these neurons decreases. In homosexu al men this nucleus is larger than in heterosexual men. The difference between the sexually dimorphic nuclei of men and women arises between the ages of 2-4 to puberty. In adult men this nucleus is twice as lar ge as in adult women. In the process of aging, a sex-dependent decreas e in cell number occurs. The vasopressin and oxytocin cells of the sup raoptic and paraventricular nucleus are present in adult numbers as ea rly as mid-gestation. Lower oxytocin neuron numbers are found in Prade r-Willi syndrome, AIDS and Parkinson's disease. Familial hypothalamic diabetes insipidus is based upon a point mutation in the vasopressin-n europhysin-glycopeptide gene. Parvicellular corticotropin-releasing ho rmone-containing neurons in the paraventricular nucleus increase in nu mber and are activated during the course of aging. In post-menopausal women, the infundibular or arcuate nucleus contains hypertrophic neuro ns containing oestrogen receptors. These neurons may be involved in th e initiation of menopausal flushes. The nucleus tuberalis lateralis ma y be involved in feeding behaviour and metabolism. In Huntington's dis ease the majority of its neurons is lost; in Alzheimer's disease it sh ows very strong cytoskeletal alterations. Tuberomammillary nucleus neu rons contain, e.g., histamine or galanine, and project to the cortex. Strong cytoskeletal changes, as well as plaques and tangles are found in this nucleus in Alzheimer's disease. The various hypothalamic nucle i are probably involved in many functions and symptoms of which only a minority has been revealed.