Neural Control of the Diaphragm Muscle
The Cell and Regenerative Physiology Lab's research on neural control of the diaphragm muscle focuses on motor units, which comprise a phrenic motor neuron located in the cervical spinal cord and the group of diaphragm muscle fibers it innervates, as the essential elements of neural control. Thus, as a phrenic motor neuron is activated by synaptic input, diaphragm muscle fibers within the motor unit are excited and contract as a unit.
The mechanical and energetic properties of the diaphragm motor unit vary considerably, and different motor unit types are recruited to accomplish a wide range of motor behaviors. Differences in mechanical and fatigue properties of diaphragm motor units are the result of expression of different contractile proteins in corresponding muscle fiber types.
Dr. Sieck's laboratory was the first to characterize the contractile and fatigue properties of different diaphragm motor unit types and to show how these motor units are recruited to accomplish different ventilatory and higher force, nonventilatory motor behaviors of the diaphragm.