Is there localized cerebral cortical influence on hypoxic ventilatory response?

A cortical inhibitory influence on net ventilatory response to hypoxia is inferred from the hyperexcitable response of decorticate cats. Electrical stimulus exploration of the cortex localizes the regions inhibitory to breathing predominantly on the orbital gyrus of the frontal lobes. The present experiments were designed to determine whether ablations of those regions of the orbital gyrus would replicate the effect of total decortication on hypoxic ventilatory response. Steady state hypoxic ventilatory response curves were determined in 8 cats under both hypocapnic and eucapnic conditions, first in the control state and second at various times after regional ablations of the orbital gyrus. Only 3 of the 8 cats showed a hyperexcitable response under hypoxia after lesioning, and they all recovered to the control state by 10 days. The isocapnic and hypocapnic responses were affected similarly. No unique contribution of this region of the brain to hypoxic ventilatory control can be documented.