Stumbling reactions in man: influence of corticospinal input |
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| Institution: | 1. Swiss Paraplegic Center, University Hospital Balgrist, University of Zürich, Forchstrasse 340, CH-8008 Zürich, Switzerland;2. Department of Medical Physics and Biophysics, University of Nijmegen, G Grooteplein N 21, NL-6525 EZ Nijmegen, The Netherlands;3. Department of Clinical Neurology and Neurophysiology, University of Freiburg, Breisacherstrasse 64, D-79106 Freiburg, Germany;1. Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany;3. Research Center for Experimental Orthopedics, Heidelberg University Hospital, Heidelberg, Germany;5. Department of Hematology and Oncology, Heidelberg University Hospital, Heidelberg, Germany;2. Department of Molecular and Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany;4. Translative Platform for Regenerative Medicine, Mossakowski Medical Research Center, Polish Academy of Sciences, Warsaw, Poland;6. Institute of Transfusion Medicine and Immunology, German Red Cross Donor Blood Service Baden-Württemberg–Hessen, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany;1. Division of Bio-Environmental Adaptation Sciences, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan;2. Department of Neurosurgery, Hiroshima University, Hiroshima, Japan;3. Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan;1. Department of Neurorehabilitation, Graduate School of Health Sciences, Kio University, 4-2-2 Umami-naka, Koryo-cho, Kitakatsuragi-gun, Nara 635-0832, Japan;2. Department of Rehabilitation, Watanabe Hospital, 45-2 Noma-kamikawada, Mihama-cho, Chita-gun, Aichi 470-3235, Japan;3. Department of Neurorehabilitation Research Center, Kio University, 4-2-2 Umami-naka, Koryo-cho, Kitakatsuragi-gun, Nara 635-0832, Japan;4. Department of Physical Therapy, Graduate School of Health Sciences, Kyoto Tachibana University, 34 Yamada-cho, Oyake, Yamashina-ku, Kyoto 607-8175, Japan;1. Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan;2. Department of Health Science, Daito Bunka University, Saitama, Japan;3. Department of Neuro-Regeneration, Fukushima Medical University, Fukushima, Japan;4. Department of Neurology, Aidu Chuo Hospital, Fukushima, Japan;1. Joint Department of Biomedical Engineering, University of North Carolina-Chapel Hill and North Carolina State University, Raleigh, NC, USA;2. Department of Bioengineering, Temple University, Philadelphia, PA, USA;1. Department of Occupational Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada;2. Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada |
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| Abstract: | The aim of this study was to evaluate the degree of contribution of supraspinal input to the generation of the compensatory leg muscle activation following stance perturbation. Therefore, evoked motor response (EMR) input–output relations of two different motor tasks were compared at 3 distinct periods: (1) the basic period of muscular activity during standing, i.e. when no additional cortical or spinal activity due to the different tasks is to be expected, (2) the pre-movement period with low background activity, when different spinal and cortical inputs to the motoneuronal pool can be assumed and (3) the period of plateau EMG activity of compensatory and voluntary motor task. Transcranial magnetic stimulation (TMS) just below the motor threshold was applied randomly at 19 different time-intervals before and during the onset of stance perturbation and for comparison during an equivalent voluntary foot-dorsiflexion task. Recordings of electromyographic (EMG) activity from the tibialis anterior (TA) and corresponding ankle-joint movements were made from both legs. Forward-directed displacements were induced by randomly-timed ramp impulses of constant acceleration upon a moveable platform. For comparison, leg muscle EMG was recorded during isometric foot dorsiflexion during stance while leaning back against a support. The stance perturbations were followed by a compensatory response (CR) in the TA with a mean onset time of 81 ms. During the basic period of muscular activity and the period of plateau EMG activity there was no significant difference of the input–output relation between stance perturbation and the voluntary motor task. However, in the voluntary task compared with the CR, there was significantly greater input–output relation (facilitation) of the EMR in the TA following TMS, which may be related to an increased cortical influence. In contrast to this result of the CR following stance perturbation, a facilitation of the EMR was described for hand muscles under corresponding conditions of automatic compensation for muscle stretch, suggesting a transcortical reflex loop. This difference in the results from upper and lower extremity muscles favors the assumption of a predominantly spinal generation of the TA-CR following stance perturbation. |
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