Our laboratory, led by Dr. Thomas Hamm, investigates the function and organization of the spinal cord systems that control motor neurons, including the organization and function of the spinal networks that produce rhythmic movements like locomotion.The activity of the motor neurons that innervate skeletal muscles determines the strength and pattern of muscle contraction. This activity is controlled by the intrinsic properties of motor neurons and the synaptic inputs they receive from other neurons—both spinal and supraspinal. Projects in the lab have concerned:
- elucidating the intrinsic properties of motoneurons
- observing control of motor neuron activity by synaptic inhibition
- cataloguing the networks of spinal neurons that produce rhythmic patterns of movement
Our goal is to understand the mechanisms of the spinal cord that generate and control voluntary movements. This information is needed to develop treatments and therapies for spinal cord injury and other disorders of the nervous system that affect movement.
Presently, our research is focused on the effects of incomplete spinal cord injury on the organization and function of motor neurons and the muscles they control. Following spinal cord injury, the properties of spinal motor neurons are altered along with the excitatory and inhibitory synaptic pathways that converge on them. This plasticity has been considered an adaptive response to injury, compensating for the loss of descending drive.
On the other hand, such alterations may be maladaptive, contributing to muscle spasticity and coactivation of antagonist muscle groups following injury that hamper movement. The plasticity of the spinal cord also offers the promise of therapies to restore function and ameliorate adverse effects following spinal cord injury through using locomotor training and reflex conditioning.
In this project, we are identifying:
- the changes that occur in motor neurons following incomplete spinal cord injuries
- the effect of exercise therapy on these changes
- the impact of these changes on motor neuron, muscle, and reflex function
We believe this research will aid the development of new therapies to assist patients with incomplete spinal cord injuries.
Thomas M. Hamm, PhD
Division of Neurobiology
Barrow Neurological Institute
350 West Thomas Road
Phoenix, Arizona 85013