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Post-Doctoral Fellow & Assistant Research Scientist, Center for Adaptive Neural Systems, Arizona State University
      • Adpative electrical stimulation for locomotor retraining after neurological impairments... << back

1] Adatpive FES-assisted locomotion therapy protocol After neural trauma, such as a spinal cord injury (SCI), a stroke, or traumatic brain injury (TBI), passive exercise or treadmill training therapy can promote activity-dependent plasticity in the spinal circuitry, thereby enhancing locomotor recovery. Evidence suggests that functional electrical stimulation of paralyzed or paretic muscles can also enhance such training therapy by activating more muscle mass and by enriching the sensory pattern with appropriately-timed muscle spindle activation. A better understanding of the neurophysiological mechanisms underlying the functional stimulation-assisted therapy could help to determine the most effective protocols for this therapeutic paradigm. As a prelude to this long-term goal, I developed a rodent model for a functional electrical stimulation-assisted therapy system that utilizes adaptive control of electrical stimulation to activate muscles in order to generate repeatable movements on the treadmill. I evaluated the ability of the adaptive controller to use agonist/antagonist control of the cyclic movement of the hip during extended trials. 2] FES therapy system (LEFT Figure) In order to measure hip and knee angle excursion in real-time, I have designed and developed a small rotary potentiometers as shown in the figure. A rotating rod rotates along the center of the potentiometer that is aligned with the hip joint, and another potentiometer that is aligned with the knee joint is attached to the rotating rod. The end part of goniometer is attached just above the ankle. The rotating rod has an additional rotational freedom, so the rod does not restrict motions occurring even in transverse plane. (RIGHT Figure) It has been suggested that load bearing and cutaneous input to the sole of the foot are likely to play an important role in recovery of stepping after spinal cord injury. I have therefore developed a platform-tread wheel system that will allow us to deliver cutaneous input during training therapy. The platform can pivot to allow loading of the hindlimbs. The hindlimbs will be allowed to move freely during FES but the foot will touch a tread-wheel to allow cutaneous feedback during the extension phase. The tread-wheel will roll freely but will automatically be lowered during hip flexion to prevent the dorsal part of the foot from touching the wheel.

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• Kim SJ, Boninger M, Cooper R, Koontz A, Souza A, “Wheelchair Braking Biomechanics”, Resna Conference, Menneapolis, Minesota, July, 2002. (PDF)
• Badi A.N., Kim S. J., Shelton C., Normann R.A., “Electrode Independence in a Novel VIII Nerve Auditory Prostheses”. Society for Neuroscience, New Orleans, 2003.
• Kim SJ, Manyam S, Badi AN, Normann RA, “Neural Responses in Feline Auditory Cortex to Direct Auditory Nerve Stimulation”, Soc. Neurosci. Abs., 2004. (PDF)
• Kim SJ, Badi AN, Normann RA, “Electrophysiological Mapping of Cat Primary Auditory Cortex with Microelectrode Arrays”, Soc. Neurosci. Abs., 2005. (PDF)
•Kim SJ, Mukherjee M, Jung R, “Adaptive electrical stimulation for rodent locomotion training produces fatigue-resistant responses", Int. Neurotrauma Symposium, 2007.(PDF)
•Kim SJ, Mukherjee M, Jung R, “Adaptive Control for Neuromuscular Stimulation Therapy in an Intermittent Training Paradigm", BMES, 2007.(PDF)
•Kim J, Cho S, Kim SJ, “Preliminary Studies to Develop a Ubiquitous Computing and Health-monitoring System for Wheelchair Users", BodyNets, Tempe, AZ, March, 2008.(PDF)
•Andrade J, Kim SJ, Christensen D.A., “Bioengineering Education via Projects and Activities for an Interactive Science Center: the University of Utah Experience”, 3rd Biomedical Engineering Education Summit Meeting, St. Charles, IL, June, 2008. (PDF)
•Abbas J, Kim SJ, Fairchild M, Allison S, Krishnamurthi N, Jung R, “On the Use of Adaptive Control in Stimulation-Assisted Neuromotor Therapy”, International FES Society Conference, German, 2008.(PDF)
•M Fairchild, JL Burton, SJ Kim, JJ Abbas, R Jung, “Use of adaptive neuromuscular electrical stimulation for hip movement in an incomplete spinal cord injury rodent model”, Soc. Neurosci. Abs., 2009. (PDF)