Suprapontine mechanisms in regulation of respiration

Abstract
The ventilation and blood acid-base balance of 19 cats were studied after supracollicular ablation of the forebrain and again after intercollicular transection of the brain stem. The first ablation caused a marked increase in the frequency of respiration, apparently unmasking a caudad facilitory influence through the removal of forebrain inhibition. Hypocapnic apnea could not be induced in this preparation. After intercollicular section there was a sudden fall in frequency, the ventilatory response to CO2 was diminished and hypocapnic apnea was easily induced. It is concluded that a tonic facilitory effect on respiration originates in the rostral midbrain and adjacent diencephalon, possibly in the reticular activating system.