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ELECTROMYOGRAPHY OF SPINAL CORD INJURED RODENTS TRAINED BY NEUROMUSCULAR ELECTRICAL STIMULATION TIMED TO ROBOTIC TREADMILL TRAINING by Sina Askari A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Ful llment of the Requirements for the Degree MASTER OF SCIENCE (BIOMEDICAL ENGINEERING) August 2012 Copyright 2012 Sina Askari
|Title||Electromyography of spinal cord injured rodents trained by neuromuscular electrical stimulation timed to robotic treadmill training|
|Degree||Master of Science|
|Degree program||Biomedical Engineering|
|School||Viterbi School of Engineering|
|Advisor (committee chair)||
Grzywacz, Norberto M.
Won, Deborah S.
|Advisor (committee member)||
Weiland, James D.
Loeb, Gerald E.
|Abstract||Neuromuscular electrical stimulation (NMES) has been used as a therapeutic tool for patients of neuromotor dysfunction to effectively regain some motor functions. It achieves this restoration of function by causing muscle contractions by applying electrical impulses to peripheral nerves. ❧ We have developed an NMES system for a rodent model of spinal cord injury (SCI) with the long term goal of creating a therapy which restores control over stepping back to the spinal circuitry. The therapy times NMES applied to the tibialis anterior (TA) ankle flexor muscle at the initial portion of the swing phase during robotic treadmill training (RTT) in an attempt to reinforce afferent activity generated just during treadmill stepping. ❧ Two studies were conducted to evaluate our proposed NMES+RTT therapy. In the first study, we compared the changes in electromyographic (EMG) activity of spinally contused rats who received NMES timed to the afferent feedback generated during robotic treadmill training (RTT) with rats receiving patterned NMES but randomly timed with respect to their hindlimb movements. The results indicated that stimulation appropriately timed to robotically treadmill training reshaped the EMG profile such that the EMG energy was concentrated during the initial portion of the swing phase, the same portion of the gait cycle during which stimulation was applied during training; in contrast, patterned stimulation alone did not lead to any consistent pattern in the EMG profile. ❧ We conducted a second study with a longitudinal cross-over design to compare the effect of NMES+RTT on modifications in EMG activity with that of RTT only. On average, both types of training helped to modulate TA EMG activity over a gait cycle, resulting in more consistent EMG profiles across steps with peaks occurring just before or at the beginning of the swing phase, when ankle flexion is most needed. RTT appeared to be important for helping rats to generate appropriate muscle activation for stepping. However, NMES+RTT resulted in EMG activation being concentrated during the initial swing phase more than RTT only. We also studied the stepping trajectory performances of each individual rats within each group. The result suggests that NMES+RTT therapy exhibits more consistent stepping and more like pre-programmed trajectory. These improvements were consistent with the notion that NMES timed appropriately to hindlimb stepping could help to reinforce the motor learning that is induced by afferent activity generated by treadmill training. ❧ The work presented in this thesis contributes to a better understanding of how NMES therapy could be designed to induce long-term changes in motor control of stepping and thus eventually lead to a therapy to better rehabilitate walking in spinal cord injury patients.|
|Keyword||EMG processing and applications; motor neuroprostheses; neuromuscular stimulation; neuromuscular systems|
|Part of collection||University of Southern California dissertations and theses|
|Publisher (of the original version)||University of Southern California|
|Place of publication (of the original version)||Los Angeles, California|
|Publisher (of the digital version)||University of Southern California. Libraries|
|Provenance||Electronically uploaded by the author|
|Legacy record ID||usctheses-m|
|Contributing entity||University of Southern California|
|Physical access||The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given.|
|Repository name||University of Southern California Digital Library|
|Repository address||USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA|
|Contributing entity||University of Southern California|
|Full text||ELECTROMYOGRAPHY OF SPINAL CORD INJURED RODENTS TRAINED BY NEUROMUSCULAR ELECTRICAL STIMULATION TIMED TO ROBOTIC TREADMILL TRAINING by Sina Askari A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Ful llment of the Requirements for the Degree MASTER OF SCIENCE (BIOMEDICAL ENGINEERING) August 2012 Copyright 2012 Sina Askari|