Crystal L Massie1, Shailesh S Kantak2, Priya Narayanan3, George F Wittenberg4. 1. Physical Therapy and Rehabilitation Sciences Department, University of Maryland School of Medicine, Baltimore, MD 21201, USA. 2. Moss Rehabilitation Research Institute, Elkins Park, PA 19027, USA; Physical Therapy and Rehabilitation Sciences Department, University of Maryland School of Medicine, Baltimore, MD 21201, USA. 3. Department of Neurology, University of Maryland School of Medicine, and Maryland Exercise and Robotics Center of Excellence, Veterans Affairs Medical Center, Baltimore, MD 21201, USA. 4. Geriatrics Research, Education & Clinical Center, Veterans Affairs Medical Center, Baltimore, MD 21201, USA; Department of Neurology, University of Maryland School of Medicine, and Maryland Exercise and Robotics Center of Excellence, Veterans Affairs Medical Center, Baltimore, MD 21201, USA; Physical Therapy and Rehabilitation Sciences Department, University of Maryland School of Medicine, Baltimore, MD 21201, USA. Electronic address: gwittenb@grecc.umaryland.edu.
Abstract
OBJECTIVE: The objective was to determine how stimulation timing applied during reaching influenced neuroplasticity related to practice. Older adult participants were studied to increase relevance for stroke rehabilitation and aging. METHODS: Sixteen participants completed 3 sessions of a reaching intervention with 480 planar robotic movement trials. Sub-threshold, single-pulse transcranial magnetic stimulations (TMS) were delivered during the late reaction time (LRT) period, when muscle activity exceeded a threshold (EMG-triggered), or randomly. Assessments included motor evoked potentials (MEP), amplitude, and direction of supra-threshold TMS-evoked movements and were calculated as change scores from baseline. RESULTS: The direction of TMS-evoked movements significantly changed after reaching practice (p<0.05), but was not significantly different between conditions. Movement amplitude changes were significantly different between conditions (p<0.05), with significant increases following the LRT and random conditions. MEP for elbow extensors and flexors, and the shoulder muscle that opposed the practice movement were significantly different between conditions with positive changes following LRT, negative changes following EMG-triggered, and no changes following the random condition. Motor performance including movement time and peak velocity significantly improved following the training but did not differ between conditions. CONCLUSIONS: The responsiveness of the motor cortex to stimulation was affected positively by stimulation during the late motor response period and negatively during the early movement period, when stimulation was combined with robotic reach practice. SIGNIFICANCE: The sensitivity of the activated motor cortex to additional stimulation is highly dynamic.
OBJECTIVE: The objective was to determine how stimulation timing applied during reaching influenced neuroplasticity related to practice. Older adult participants were studied to increase relevance for stroke rehabilitation and aging. METHODS: Sixteen participants completed 3 sessions of a reaching intervention with 480 planar robotic movement trials. Sub-threshold, single-pulse transcranial magnetic stimulations (TMS) were delivered during the late reaction time (LRT) period, when muscle activity exceeded a threshold (EMG-triggered), or randomly. Assessments included motor evoked potentials (MEP), amplitude, and direction of supra-threshold TMS-evoked movements and were calculated as change scores from baseline. RESULTS: The direction of TMS-evoked movements significantly changed after reaching practice (p<0.05), but was not significantly different between conditions. Movement amplitude changes were significantly different between conditions (p<0.05), with significant increases following the LRT and random conditions. MEP for elbow extensors and flexors, and the shoulder muscle that opposed the practice movement were significantly different between conditions with positive changes following LRT, negative changes following EMG-triggered, and no changes following the random condition. Motor performance including movement time and peak velocity significantly improved following the training but did not differ between conditions. CONCLUSIONS: The responsiveness of the motor cortex to stimulation was affected positively by stimulation during the late motor response period and negatively during the early movement period, when stimulation was combined with robotic reach practice. SIGNIFICANCE: The sensitivity of the activated motor cortex to additional stimulation is highly dynamic.
Authors: Mark M Churchland; John P Cunningham; Matthew T Kaufman; Stephen I Ryu; Krishna V Shenoy Journal: Neuron Date: 2010-11-04 Impact factor: 17.173
Authors: Min-Fang Kuo; Mandy Unger; David Liebetanz; Nicolas Lang; Frithjof Tergau; Walter Paulus; Michael A Nitsche Journal: Neuropsychologia Date: 2008-02-29 Impact factor: 3.139
Authors: Susan S Conroy; Jill Whitall; Laura Dipietro; Lauren M Jones-Lush; Min Zhan; Margaret A Finley; George F Wittenberg; Hermano I Krebs; Christopher T Bever Journal: Arch Phys Med Rehabil Date: 2011-08-17 Impact factor: 3.966
Authors: Viola Giacobbe; Bruce T Volpe; Gary W Thickbroom; Felipe Fregni; Alvaro Pascual-Leone; Hermano I Krebs; Dylan J Edwards Journal: J Neuroeng Rehabil Date: 2011-08-24 Impact factor: 4.262