Separate Localization in the Medulla Oblongata of the Vagal Inspiratory and Expiratory Reflex Centers

Abstract

The column of gray matter accompanying the tractus solitarius is probably the locus proper of the vagal respiratory reflex centers. This nuclear column may be regarded as the common interneurone pool for these reflexes, with a cranial part of expiratory, i.e., inspiratory-inhibitory, and a caudal part of inspiratory-excitatory, internuncial neurones. It is suggested that these solitary interneurones control the inspiratory motoneurones directly, in an excitatory as well as in an inhibitory way. However, a higher reflex integration involving the autonomous divisions of the respiratory center also exists, since it alone could explain certain features of the vagal control of breathing.