Drive to the human respiratory muscles

Area of Science:

• Neuroscience
• Respiratory Physiology
• Motor Control

Background:

• Motor control of respiratory muscles differs from limb muscles.
• Respiratory muscles are controlled by descending pathways from the medulla (quiet breathing) and motor cortex (voluntary breathing).

Purpose of the Study:

• To investigate the distribution and integration of neural drive to respiratory muscles during automatic and voluntary breathing.
• To explore the implications for limb motor control.

Main Methods:

• Neurophysiological studies of single motor unit activity in human subjects.
• Analysis of motor unit activity in diaphragm and intercostal muscles during normal and voluntary breathing tasks.

Main Results:

• Neural drive is not uniformly distributed to all respiratory muscles; it follows a principle of neuromechanical matching.
• Motoneurones innervating muscles with greater mechanical advantage are more active.
• Motor unit recruitment in the diaphragm changes significantly during voluntary tasks, indicating variable descending drive.

Conclusions:

• Understanding respiratory muscle drive integration and distribution is crucial for comprehending both automatic and voluntary breathing.
• Findings suggest potential implications for understanding limb motor control.