Fiber Systems Between the Lower Brain Stem and the Hypothalamus
As mentioned in the Introduction, using light microscope degeneration Szentágothai et al. (1962) were able to show that most of the afferentation to the medial hypothalamus originates from the brain stem. Various brain stem structures stimulate or inhibit the secretion of trophic hormones. This effect implies a complex integrative activity as these brain stem areas are not only linked to various ascending pathways but are also sensitive to blood hormone levels, e.g., estrogen, androgen, progesterone, corticosterone, and aldosterone. Thus they may be related to the feedback action of various trophic hormones. (For details, see Chap. 8). Peripheral nerves and the spinal stress pathways reach the hypothalamus via the brain stem (Gann et al. 1979, Makara et al. 1980a). It is assumed that there are nerves ascending to the medial hypothalamus from the contralateral adrenal gland (Szentágothai et al. 1962, Halász 1978). Electrophysiological studies have shown that various somatosensory and viscerosensory information may pass through the brain stem to the MBH (Anand and Pillai 1967, Feldman and Dafny 1970, Haller and Barraclough 1970, Blake and Sawyer 1972, Freeman and Banks 1980).
KeywordsVentral Tegmental Area Cell Group Dorsal Raphe Nucleus Medial Forebrain Bundle Locus Ceruleus
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