The Mammalian Diving Response: Inroads to Its Neural Control

Area of Science:

• Physiology
• Neuroscience
• Autonomic Nervous System

Background:

• The mammalian diving response (DR) is a conserved physiological reaction to breath-holding and submersion.
• It is characterized by apnea, bradycardia, and peripheral vasoconstriction, primarily observed in marine mammals but present in all mammals.
• The DR conserves oxygen by redirecting blood flow to essential organs like the heart and brain.

Purpose of the Study:

• To review neuroanatomical and physiological data on the brainstem circuits controlling the mammalian diving response.
• To elucidate the neural mechanisms underlying apnea, bradycardia, and vasoconstriction during diving.
• To explore the implications of understanding the DR circuit for autonomic function and clinical applications.

Main Methods:

• Review of existing neuroanatomical and physiological studies on the diving response.
• Analysis of data from brainstem transection experiments to localize DR control centers.
• Synthesis of evidence implicating specific brainstem areas in mediating the DR components.

Main Results:

• The neural circuits for the DR are located in the medulla and spinal cord, persisting after pontomedullary junction transection.
• Specific brainstem areas are identified as crucial for initiating and coordinating apnea, bradycardia, and peripheral vasoconstriction.
• The DR significantly modulates homeostatic reflexes, including baroreceptor and chemoreceptor reflexes.

Conclusions:

• The diving response is a potent autonomic reflex with its core circuitry in the lower brainstem.
• Understanding the DR's neural basis offers insights into suprabulbar control of autonomic function.
• Knowledge of the DR circuit can advance research in areas such as elite diving, SIDS, stroke, and cardiac arrhythmias.