Is there localized cerebral cortical influence on hypoxic ventilatory response?

Area of Science:

• Neuroscience
• Respiratory Physiology
• Behavioral Neuroscience

Background:

• Cortical inhibitory influences on the net ventilatory response to hypoxia are suggested by hyperexcitable responses in decorticate animals.
• Previous research localized potential inhibitory regions for breathing to the orbital gyrus of the frontal lobes via electrical stimulation.

Purpose of the Study:

• To determine if ablating specific regions of the orbital gyrus replicates the effect of total decortication on the hypoxic ventilatory response.
• To investigate the contribution of the orbital gyrus to the control of breathing during hypoxia.

Main Methods:

• Steady-state hypoxic ventilatory response curves were measured in 8 cats under hypocapnic and eucapnic conditions.
• Measurements were taken in a control state and at various times after regional ablations of the orbital gyrus.

Main Results:

• Only 3 out of 8 cats exhibited a hyperexcitable response to hypoxia after orbital gyrus lesioning.
• These 3 cats returned to their baseline control state within 10 days post-lesioning.
• Both isocapnic and hypocapnic ventilatory responses were similarly affected, showing no unique regional contribution.

Conclusions:

• Regional ablations of the orbital gyrus did not consistently alter the hypoxic ventilatory response in cats.
• The study did not document a unique contribution of the orbital gyrus to hypoxic ventilatory control.
• Further research may be needed to fully elucidate the role of the cerebral cortex in respiratory regulation during hypoxia.