Many individuals with spinal cord injury cannot generate the muscle torque necessary for efficient locomotion even after extensive rehabilitation. This may be attributed to both neural and muscular declines after injury. However, the ability to step and stand can be reacquired by mammals even after a complete thoracic spinal cord transection by task specific training that maintains appropriate peripheral sensory inputs. This potential for neural plasticity may also exist in human lumbosacral neural circuits. Spinal cord injured patients who have no detectable voluntary motor control or sensation below the level of the lesion can generate step like efferent patterns when suspended over a moving treadmill belt with partial body weight support with manual assistance. Further, peripheral sensory modalities such as limb load, speed of locomotion, joint position and cycle period may modulate the EMG activity of extensors and flexors during stepping on the treadmill by interacting with lumbosacral neural circuits. Repetitive step training may have enduring effects on the capacity of these neural networks and has the potential to reduce the effects of muscle disuse. In the proposed experiments the Principal Investigator aims to determine 1) the responsiveness of the human lumbosacral spinal cord after a clinically complete thoracic injury to sensory inputs related to limb load, the kinematics of the phases of the step cycle, and hip position during stepping with body weight support on a moving treadmill. 2) whether training with these inputs can optimize the level of motor pool activity and increase muscle mass and therefore the potential for locomotion, the proposed studies will employ measures of kinematics, loading, and electromyographic activity of the lower limbs. The results will provide a better understanding of neural mechanisms that are available in the human spinal cord to generate locomotion and will facilitate the development of new rehabilitation strategies for optimizing the recovery of mobility following neurologic injury.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS036854-02
Application #
2892341
Study Section
Special Emphasis Panel (ZRG4-GRM (01))
Program Officer
Chiu, Arlene Y
Project Start
1998-05-01
Project End
2002-04-30
Budget Start
1999-05-01
Budget End
2000-04-30
Support Year
2
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Neurology
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
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Dy, Christine J; Gerasimenko, Yury P; Edgerton, V Reggie et al. (2010) Phase-dependent modulation of percutaneously elicited multisegmental muscle responses after spinal cord injury. J Neurophysiol 103:2808-20
Behrman, A L; Harkema, S J (2000) Locomotor training after human spinal cord injury: a series of case studies. Phys Ther 80:688-700