Direct hypothalamo-autonomic connections
Saper CB, Loewy AD, Swanson LW, and Cowan WM (1976) Direct hypothalamo-autonomic connections. Brain Res 117:2 305–12.
Abstract: That the hypothalamus exerts an important regulatory influence on the autonomic nervous system has long been known, but the exact pathways through which this influence is mediated have not been established. Physiological studies, principally by Ranson, Magoun and their co-workers, have indicated that there are descending hypothalamic pathways which extend caudally through the midbrain tegmentum into the lateral funiculus of the spinal cord to reach the intermediolateralcell column. These experiments, combining electrical stimulation and lesions at various levels, established that the descending pathways are bilateral, some fibers crossing to the contralateral side at virtually all levels. However, it was impossible to determine from studies of this kind whether the pathways involved are direct or polysynaptic. From time to time reports have appeared in the neuroanatomical literature suggesting that there may be a direct input from the hypothalamus to the preganglionic sympathetic outflow in the spinal cord but, as yet, these have not been confirmed, and in most experimental studies using axonal degeneration techniques, it has not been possible to trace degenerating fibers much beyond the caudal midbrain or rostral pons. As a result, the consensus of opinion has been that the hypothalamus influences the autonomic centers of the brain stem and spinal cord through a system of poorly defined connections through the brain stem reticular formation.
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