Organization of Central Respiratory Mechanisms in the Brain Stem of the Cat: Localization by Stimulation and Destruction

Abstract

With electrical stimulation and circumscribed electrolytic destruction, the pneumotaxic center is localized in the dorsolateral reticular formation of the isthmus of the pons. Destruction of the pneumotaxic center and vagotomy result in apneustic respiration. The pneumotaxic center functions independently to modulate and facilitate the phasic activity of the lower respiratory centers. This function is analogous to that of the pulmonary vagal afferents. The apneustic center is probably localized in the lateral reticular formation of the middle pons and extends medially toward the caudal portion of the pons. The medullary inspiratory center is localized in the ventral reticular formation rostral to and at the level of the obex. Stimulation of these structures yields marked inspiratory spasm. Forced expiratory responses are obtained on stimulation of a circumscribed area in the dorsal portion of the medulla 1–3 mm caudal to the obex, which probably constitutes the expiratory center.