1. Transcranial magnetic stimulation induced early silent period and rebound activity re-examined
- Author
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Özyurt, Mustafa, Haavik, Heidi, Nedergaard, Rasmus, Topkara, Betilay, Şenocak, Beatrice, Göztepe, Mehmet, Niazi, Imran, Türker, Kemal, Türker, Kemal Sıtkı (ORCID 0000-0001-9962-075X & YÖK ID 6741), Özyurt, Mustafa Görkem, Topkara, Betilay, Haavik, Heidi, Nedergaard, Rasmus Wiberg, Şenocak, Beatrice Selen, Göztepe, Mehmet Berke, Niazi, İmran Khan, School of Medicine, Graduate School of Sciences and Engineering, Graduate School of Health Sciences, Department of Physiology, Department of Biomedical Sciences and Engineering, and Department of Neuroscience
- Subjects
Male ,030506 rehabilitation ,Muscle Physiology ,Tibialis anterior ,Physiology ,Synaptic Potential ,medicine.medical_treatment ,Action Potentials ,Electromyography ,0302 clinical medicine ,Medicine and Health Sciences ,Evoked potential ,Synaptic potential ,Motor Neurons ,Brain Mapping ,Multidisciplinary ,EPSP ,Single unit ,medicine.diagnostic_test ,Chemistry ,Motor Cortex ,Brain ,Synaptic Potentials ,Transcranial Magnetic Stimulation ,Electrophysiology ,medicine.anatomical_structure ,Bioassays and Physiological Analysis ,Brain Electrophysiology ,Excitatory postsynaptic potential ,Medicine ,Engineering and Technology ,IPSP ,Female ,Anatomy ,0305 other medical science ,Muscle Electrophysiology ,Motor cortex ,Research Article ,Muscle Contraction ,Science ,Neurophysiology ,Abductor pollicis brevis ,cortical silent period ,Inhibitory postsynaptic potential ,Research and Analysis Methods ,Membrane Potential ,03 medical and health sciences ,medicine ,Humans ,Motor evoked potential ,Muscle, Skeletal ,Transcranial Stimulation ,Electrodes ,Electrophysiological Techniques ,Excitatory Postsynaptic Potentials ,Biology and Life Sciences ,Frequency ,Transcranial magnetic stimulation ,Silent period ,Electronics ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Despite being widely studied, the underlying mechanisms of transcranial magnetic brain stimulation (TMS) induced motor evoked potential (MEP), early cortical silent period (CSP) and rebound activity are not fully understood. Our aim is to better characterize these phenomena by combining various analysis tools on firing motor units. Responses of 29 tibialis anterior (TA) and 8 abductor pollicis brevis (APB) motor units to TMS pulses were studied using discharge rate and probability-based tools to illustrate the profile of the synaptic potentials as they develop on motoneurons in 24 healthy volunteers. According to probability-based methods, TMS pulse produces a short-latency MEP which is immediately followed by CSP that terminates at rebound activity. Discharge rate analysis, however, revealed not three, but just two events with distinct time courses; a long-lasting excitatory period (71.2 ± 9.0 ms for TA and 42.1 ± 11.2 ms for APB) and a long-latency inhibitory period with duration of 57.9 ± 9.5 ms for TA and 67.3 ± 13.8 ms for APB. We propose that part of the CSP may relate to the falling phase of net excitatory postsynaptic potential induced by TMS. Rebound activity, on the other hand, may represent tendon organ inhibition induced by MEP activated soleus contraction and/or long-latency intracortical inhibition. Due to generation of field potentials when high intensity TMS is used, this study is limited to investigate the events evoked by low intensity TMS only and does not provide information about later parts of much longer CSPs induced by high intensity TMS. Adding discharge rate analysis contributes to obtain a more accurate picture about the characteristics of TMS-induced events. These results have implications for interpreting motor responses following TMS for diagnosis and overseeing recovery from various neurological conditions., Chiropractic Center of New Zealand; Koç University School of Medicine; Scientific and Technological Research Council of Turkey (TÜBİTAK) 2211-A National Scholarship Programme for PhD Students; Australian Spine Research Foundation (ASRF)
- Published
- 2019