Pontine afferents to the medullary respiratory system: anatomofunctional correlation

A direct projection from the parabrachialis medialis, Kölliker-Fuse complex (PMKF) to the bulbar respiratory area is shown using autoradiography. Perikarya of PMKF project to the medulla, labelled fibers and terminals being located radially to the fourth ventricle from the nucleus hypoglossus to the ambiguus. The functional importance of this projection is demonstrated in pharmacological studies using iontophoresis of L-glutamate which enable identification of somatodendritic discharges. A good correlations exists between the localization in the medulla of labelled fibers and terminals and that of an inspiratory background activity related to inspiratory fibers or terminals.