Neural regulation of respiration.

During the last decade, we have seen our knowledge of the neural regulation of respiration progress from the concept of "respiratory centers" to that of densely packed groups of respiratory neurons located within specific medullary nuclei. By careful neurophysiological and histological studies employing intra- and extracellular recording, the sequence of processing of afferent information through these nuclei and the axonal projections from respiratory neurons have been determined. However, the site and the mechanism of respiratory rhythm generation remain unknown.