Figure 31. Schematic diagram showing autonomic regulation of corticotropin-releasing hormone (CRH) neurons of the hypothalamic tuberoinfundibular tract. (1) Visceral sensory information carried by the glossopharyngeal (IX) and vagus (X) nerves terminates in lower brain stem autonomic centers which (2) project to CRH neurons in the paraventricular nucleus (PVN), (3) modulating the secretion of CRH into the portal capillary system in the median eminence (ME). Descending pathways from the PVN reach autonomic centers in the (4) lower brainstem and (5) spinal cord and can influence the autonomic nervous system. (6) CRH neurons also receive direct input from the limbic system via bed nucleus of the stria terminalis. IML = intermediolateral cell column of the spinal cord. (Schematic diagram based on rat data and modified from Sawchenko PE, Swanson LW, Science 1981; 214:685-687.)