Learned control of heart rate during dynamic exercise in nonhuman primates

Area of Science:

• Exercise physiology
• Neuroscience
• Cardiovascular research

Background:

• Understanding the interplay between cardiovascular, pulmonary, and somatomotor systems during exercise is crucial.
• Central command influences these systems, but its precise dissociation requires further investigation.

Purpose of the Study:

• To describe a novel animal model for examining the relationships among cardiovascular, pulmonary, and somatomotor command systems during exercise.
• To investigate the dissociation of these systems using operant conditioning.

Main Methods:

• Three chronically instrumented monkeys (Macaca mulatta) were trained using operant conditioning.
• Animals were conditioned to exercise (weight lifting) and to attenuate heart rate responses, both independently and combined.
• Physiological parameters including heart rate, blood pressure, and expired gas concentrations were recorded.

Main Results:

• Monkeys successfully learned to attenuate heart rate during exercise, showing significantly reduced heart rate increases compared to exercise-only conditions.
• Rate-pressure product differences paralleled heart rate changes, indicating a coordinated cardiovascular response.
• Cardiovascular reactivity relative to oxygen consumption was attenuated during combined sessions, even when work done was equated.

Conclusions:

• The developed animal model effectively demonstrates a dissociation between cardiovascular and somatomotor responses to central command during exercise.
• This model allows for the study of adaptive control of autonomic and motor systems.
• Findings suggest that central command can independently modulate cardiovascular and motor outputs.