Suprapontine control of respiration

Despite focus on brainstem areas in central respiratory control, regions ro stral to the medulla and pens are now recognized as being important in modu lating respiratory outflow during various physiological states. The focus o f this review is to highlight the role that suprapontine areas of the mamma lian brain play in ventilatory control mechanisms. New imaging techniques h ave become invaluable in confirming and broadening our understanding of the manner in which the cerebral cortex of humans contributes to respiratory c ontrol during volitional breathing. In the diencephalon, the integration of respiratory output in relation to changes in homeostasis occurs in the cau dal hypothalamic region of mammals. Most importantly, neurons in this regio n are strongly sensitive to perturbations in oxygen tension which modulates their level of excitation. In addition, the caudal hypothalamus is a major site for 'central command', or the parallel activation of locomotion and r espiration. Furthermore, midbrain regions such as the periaqueductal gray a nd mesencephalic locomotor region function in similar fashion as the caudal hypothalamus with regard to locomotion and more especially the defense rea ction. Together these suprapontine regions exert a strong modulation upon t he basic respiratory drive generated in the brainstem. (C) 1998 Elsevier Sc ience B.V. All rights reserved.