Volker Zschorlich | University of Rostock (original) (raw)

Papers by Volker Zschorlich

Brain Sciences

Traumatic brain injury, cardiac arrest, intracerebral hemorrhage, and ischemic stroke may cause d... more Traumatic brain injury, cardiac arrest, intracerebral hemorrhage, and ischemic stroke may cause disorders of consciousness (DoC). Repetitive transcranial magnetic stimulation (rTMS) has been used to promote the recovery of disorders of consciousness (DoC) patients. In this meta-analysis, we examined whether rTMS can relieve DoC patient symptoms. We searched through journal articles indexed in PubMed, the Web of Science, Embase, Scopus, and the Cochrane Library until 20 April 2023. We assessed whether studies used rTMS as an intervention and reported the pre- and post-rTMS coma recovery scale-revised (CRS-R) scores. A total of 207 patients from seven trials were included. rTMS significantly improved the recovery degree of patients; the weighted mean difference (WMD) of the change in the CRS-R score was 1.89 (95% confidence interval (CI): 1.39–2.39; p < 0.00001) in comparison with controls. The subgroup analysis showed a significant improvement in CRS-R scores in rTMS over the dors...

Brain sciences, Jan 24, 2024

Clinical Neurophysiology, Sep 1, 2022

Frontiers in Neuroscience, 2019

Pathways of the human mirror neuron system are activated during both, action observation and acti... more Pathways of the human mirror neuron system are activated during both, action observation and action execution, including lateralized activation of respective areas, as shown by observed right-or left-hand actions. Here, we investigated whether execution-dependent motor cortex excitability is affected by prior interaction between transcranial random noise stimulation (tRNS) and action observation. Sham or real tRNS (1 mA) was applied for 10-min over the left primary motor cortex during action observation. In the main experiments, participants received sham or real tRNS while they watched a video showing repeated tapping tasks, involving either the righthand (Experiment 1, congruent action observation), or a mirror-reversed video showing the same performance (Experiment 2), followed by action execution of the righthand. In control Experiments 1-3, participants received real tRNS while observing a perceptual sequence, watching a landscape picture, or observing the left-hand performing the action (the sequence was identical to Experiment 1), followed by action execution of the right-hand. In control Experiment 4, participants received real tRNS during congruent action observation, and then took 6-min rest. Motor-evoked potentials (MEP) were recorded before action observation, a perceptual sequence or a landscape picture, immediately after, and after action execution, or an interval of 6min, dependent on the respective experimental condition. MEPs in the right first dorsal interosseous muscle increased significantly after real tRNS combined with congruent action observation, and after action execution compared to the sham session in Experiment 1 and control experiments. We conclude that prior interaction between real tRNS and action observation of mirror-matched movements modulates subsequent execution-dependent motor cortex excitability.

Frontiers in Bioengineering and Biotechnology, 2019

BMC Musculoskeletal Disorders, 2012

Background: It is often suggested that sagittal instability at the first tarso-metatarsal joint l... more Background: It is often suggested that sagittal instability at the first tarso-metatarsal joint level is a primary factor for hallux valgus and that sagittal instability increases with the progression of the deformity. The assessment of the degree of vertical instability is usually made by clinical evaluation while any measurements mostly refer to a static assessment of medial ray mobility (i.e. the plantar/dorsal flexion in the sagittal plane). Testing methods currently available cannot attribute the degree of mobility to the corresponding anatomical joints making up the medial column of the foot. The aim of this study was to develop a technique which allows for a quantification of the invivo sagittal mobility of the joints of the medial foot column during the roll-over process under full weight bearing. Methods: Mobility of first ray bones was investigated by dynamic distortion-free fluoroscopy (25 frames/s) of 14 healthy volunteers and 8 patients with manifested clinical instability of the first ray. A CAD-based evaluation method allowed the determination of mobility and relative displacements and rotations of the first ray bones within the sagittal plane during the stance phase of gait. Results: Total flexion of the first ray was found to be 13.63 (SD 6.14) mm with the healthy volunteers and 13.06 (SD 8.01) mm with the patients (resolution: 0.245 mm/pixel). The dorsiflexion angle was 5.27 (SD 2.34) degrees in the healthy volunteers and increased to 5.56 (SD 3.37) degrees in the patients. Maximum rotations were found at the naviculo-cuneiform joints and least at the first tarso-metatarsal joint level in both groups. Conclusions: Dynamic fluoroscopic assessment has been shown to be a valuable tool for characterisation of the kinematics of the joints of the medial foot column during gait. A significant difference in first ray flexion and angular rotation between the patients and healthy volunteers however could not be found.

Brain Sciences, 2021

Background: Brain stimulation motor-evoked potentials (MEPs) are transient signals and not period... more Background: Brain stimulation motor-evoked potentials (MEPs) are transient signals and not periodic signals, and thus, they differ significantly in their properties from classical surface electromyograms. Unsuitable pre-processing of MEPs due to inappropriate filter settings leads to distortions. Filtering of extensor carpi radialis MEPs with transient signal characteristics of 20 subjects was examined. The effects of a 1st-order Butterworth high-pass filter (HPF) with different cut-off frequencies 1 Hz, 20 Hz, 40 Hz, and 80 Hz and a 5 Hz Butterworth high-pass filter with degrees 1st, 2nd, 4th, 8th-order are investigated for the filter output. Results: The filtering of the MEPs with an inappropriate filter setting led to distortions on the parameters peak-to-peak amplitudes of the MEP (MEPpp) and the absolute integral of the MEP (MEParea). The lowest distortions of all of the examined filter parameters were revealed after filtering with the lowest filter order and the lowest cut-off...

Optimal motor control requires the effective integration of multi-modal information. Visual infor... more Optimal motor control requires the effective integration of multi-modal information. Visual information of movement performed by others even enhances potentials in the upper motor neurons, through the mirror-neuron system. On the other hand, it is known that motor control is intimately associated with afferent proprioceptive information. Kinaesthetic information is also generated by passive, external-driven movements. In the context of sensory integration, its an important question, how such passive kinaesthetic information and visually perceived movements are integrated. We studied the effects of visual and kinaesthetic information in combination, as well as isolated, on sensorimotor-integration – compared to a control condition. For this, we measured the change in the excitability of motor cortex (M1) using low-intensity TMS. We hypothesised that both visual motoneurons and kinaesthetic motoneurons could enhance the excitability of motor responses. We found that passive wrist move...

Journal of Sports Science and Medicine, Mar 1, 2011

The electric field induced by repetitive peripheral magnetic stimulation (RPMS) is able to activa... more The electric field induced by repetitive peripheral magnetic stimulation (RPMS) is able to activate muscles artificially due to the stimulation of deep intramuscular motor axons. RPMS applied to the muscle induces proprioceptive input to the central nervous system in different ways. Firstly, the indirect activation of mechanoreceptors and secondly, direct activation of afferent nerve fibers. The purpose of the study was to examine the effects of RPMS applied to the soleus. Thirteen male subjects received RPMS once and were investigated before and after the treatment regarding the parameters maximal M wave (Mmax), maximal H-reflex (Hmax), Hmax/Mmax-ratio, Hmax and Mmax onset latencies and plantar flexor peak twitch torque associated with Hmax (PTH). Eleven male subjects served as controls. No significant changes were observed for Hmax and PTH of the treatment group but the Hmax/Mmax-ratio increased significantly (p = 0.015) on account of a significantly decreased Mmax (p = 0.027). Hm...

Electromyography and clinical neurophysiology, 1989

Even under field conditions the registration of EMG-signals is often interfered with artifacts. F... more Even under field conditions the registration of EMG-signals is often interfered with artifacts. For quantitative signal processing it is necessary to eliminate artifacts and noise from the EMG raw data. We show a simple and efficient way with the help of a recursive digital first order Butterworth filter. This filter-type has a great slope steepness and requires minimal calculations. The algorithm is derived and easily programmable.

Copyright © 2014 Tursonjan Tokay et al. This is an open access article distributed under the Crea... more Copyright © 2014 Tursonjan Tokay et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. High-frequency magnetic stimulation (HFMS) can elicit N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentia-tion (LTP) at Schaffer collateral-CA1 pyramidal cell synapses. Here, we investigated the priming effect of HFMS on the subsequent magnitude of electrically induced LTP in the CA1 region of rat hippocampal slices using field excitatory postsynaptic potential (fEPSP) recordings. In control slices, electrical high-frequency conditioning stimulation (CS) could reliably induce LTP. In contrast, the same CS protocol resulted in long-term depression when HFMS was delivered to the slice 30min prior to the electrical stimulation.HFMS-primingwas diminishedwhen applied in the presence of themetabotropic glutamate receptor ant...

Introduction: The electric field induced by magnetic stimulation (MS) is able to stimulate intram... more Introduction: The electric field induced by magnetic stimulation (MS) is able to stimulate intramuscular motor axons, which evoke muscle contraction (Machetanz, 1994). The purpose of the present study was to examine the effects of repetitive MS (rMS) of the m. soleus (So) on the Hmax/Mmax-ratio. Methods: 24 healthy male students took part in a double blind study. Subjects were randomly assigned to a treatment group (G1: n = 13; age 24.08 ± 1.98; weight 77.77 ± 7.34; height 181.31 ± 6.76) and a control group (G2: n = 11; 23.00 ± 1.55; 79.55 ± 11.67; 182.00 ± 8.31). rMS was delivered using a MagProR30 stimulator and a MC-125 circular coil. The stimulation protocol included the application of symmetric biphasic pulses, a frequency of 15 Hz, 20 trains, inter train interval 2sec, 100 bursts per train and 40% stimulator output. rMS took place once and was applied to So of G1. G2 received a placebo rMS. Before and after rMS Hmax/Mmax-ratios and torque (T in Nm), produced by plantar flexion...

Das Forschungsprojekt „Eintauchtechnik“ an der Universitat Rostock beschaftigt sich mit dem Probl... more Das Forschungsprojekt „Eintauchtechnik“ an der Universitat Rostock beschaftigt sich mit dem Problem der Spritzerbildung beim Wasserspringen aus einer interdisziplinaren Perspektive. Ein stromungsdynamisch orientiertes Teilprojekt untersucht am Institut fur Stromungstechnik (Leder und Mitarbeiter) Druckund Geschwindigkeitsverhaltnisse am Modell eines untergetauchten Wasserspringers, um insbesondere der Frage der Spritzerbildung durch Kavitationsphanomene („Spontane“ Blasenbildung durch Unterschreiten des Dampfdruckes) nachzugehen. Hier kann am Modell der Einfluss von Eintauchgeschwindigkeit und Eintauchtechnik (z.B. Durchtauchen oder Abrollen) auf die Form der Spritzerbildung studiert werden.

Das erfolgreiche Interagieren mit der Umwelt ist bezüglich der motorischen Kontrolle des Bewegung... more Das erfolgreiche Interagieren mit der Umwelt ist bezüglich der motorischen Kontrolle des Bewegungsapparates eine komplexe Aufgabe. Bei sich ändernden biomechanischen Anforderungen der Interaktion muss eine situationsadäquate Regulation der involvierten motorischen Strukturen erfolgen. Dazu müssen muskuläre sowie zentralnervöse Prozesse im Sinne der Aufgabenerfüllung aufeinander abgestimmt werden, um bspw. ein externes Objekt sicher kontrollieren zu können. Wird die Stabilität während der Aufgabenerfüllung nicht durch die Umwelt (bzw. durch das Interaktionsobjekt) gesichert, muss das neuromuskuläre System diese Ausgabe übernehmen. Dabei erfordert die gekoppelte Mechanik des Objektes mit dem motorischen Apparat spezifische muskuläre Beiträge zur Bewegung, welche sich je nach der Funktion des Muskels sowie der Aufgabe selbst in ihren Ausprägungen unterscheiden. Diese Arbeit ging der Frage nach, wie das neuromuskuläre System den Wechsel externer Bedingungen während einer Kraftproduktionsaufgabe kontrolliert. Dazu wurden an einem Bewegungsschlitten die möglichen mechanischen Freiheitsgrade (Degers of Freedom; DoF) verändert und die Antworten des muskulären Systems mittels EMG von vier Muskeln (M. vastus medialis, M. tibialis anterior, M. peroneus longus, M. gastrocnemius medialis) registriert. Zusätzlich wurden dynamometrische Messungen vorgenommen und die resultierenden Kräfte in drei Dimensionen (Fx, Fy, Fz) erfasst und ausgewertet. Die EMG-Signale wurden mittels Kreuzkorrelationsberechnungen, Anstiegsuntersuchungen, Integral-sowie Differentialberechnungen und Spitzenamplitudenbestimmungen hinsichtlich intra-und intermuskulärer Koordinationsleistungen ausgewertet. Die dynamometrischen Daten wurden durch Integration, Differenzierung, Spitzenamplitudenbestimmungen sowie Kreuzkorrelationsuntersuchungen verarbeitet. Die Ergebnisse deuten auf eine Dominanz zeitlicher Einstellungsmechanismen der muskulären Aktivität gegenüber der Höhe der muskulären Aktivierung hin. Ferner zeigten sich intra-und intermuskuläre Koordinationsmuster als aufgabenspezifisch. Die Modulationen der Aktivitätsmuster der untersuchten Muskeln müssen in diesem Zusammenhang im Sinne einer Regulation der Gelenkstabilität (joint stiffness) gewertet werden. Da die Natur der Aufgabe eine multisegmentale Bewegung abverlangte, mussten die

Frontiers in Physiology

The present study was designed to provide further insight into the mechanistic basis for the impr... more The present study was designed to provide further insight into the mechanistic basis for the improved exercise tolerance following ischemic preconditioning (IPC) by investigating key-determinants of performance and perceived fatigability. Using a randomized, counterbalanced, single-blind, sham-controlled, crossover design, 16 males performed an isometric time-to-exhaustion test with the knee extensors at 20% maximal voluntary torque (MVT) after an IPC and a sham treatment (SHAM). Those who improved their time-to-exhaustion following IPC performed a time-matched IPC trial corresponding to the exercise duration of SHAM (IPCtm). Neuromuscular function was assessed before and after exercise termination during each condition (IPC, IPCtm, and SHAM) to analyze the impact of IPC on performance fatigability and its central and peripheral determinants. Muscle oxygenation (SmO2), muscle activity, and perceptual responses (effort and muscle pain) were recorded during exercise. Performance fatigability as well as its central and peripheral determinants were quantified as percentage pre-post changes in MVT (ΔMVT) as well as voluntary activation (ΔVA) and quadriceps twitch torque evoked by paired electrical stimuli at 100 and 10 Hz (ΔPS100 and ΔPS10⋅PS100–1 ratio), respectively. Time-to-exhaustion, performance fatigability, its determinants, muscle activity, SmO2, and perceptual responses during exercise were not different between IPC and SHAM. However, six participants improved their performance by >10% following IPC (299 ± 71 s) compared to SHAM (253 ± 66 s, d = 3.23). The time-matched comparisons (IPCtm vs. SHAM) indicated that performance fatigability, its determinants, and SmO2 were not affected, while effort perception seemed to be lower (ηp2 = 0.495) in those who improved their time-to-exhaustion. The longer time-to-exhaustion following IPC seemed to be associated with a lower effort perception (ηp2 = 0.380) and larger impairments in neuromuscular function, i.e., larger ΔMVT, ΔVA, and ΔPS10⋅PS100–1 ratio (d = 0.71, 1.0, 0.92, respectively). IPC did neither affect exercise tolerance, performance fatigability, as well as its central and peripheral determinants, nor muscle activity, SmO2, and perceptual responses during submaximal isometric exercise. However, IPC seemed to have an ergogenic effect in a few subjects, which might have resulted from a lower effort perception during exercise. These findings support the assumption that there are ‘responders’ and ‘non-responders’ to IPC.