Visual Universitätsmedizin Mainz

Movement disorders, neurostimulation and neuroimaging

In addition to our clinical work, scientific research plays an important role in the Section for Movement Disorders and Neurostimulation of the University Medical Center Mainz. In our projects, we investigate how different regions of the brain interact with one another, both in healthy people and those suffering from neurological diseases, particularly focusing on connectivity and reorganization. We employ imaging, non-invasive stimulatory and electrophysiological methodologies to explore the physiology and pathophysiology of the human motoric system.

Currently we are working on several studies of patients with movement disorders (incl. Parkinson's), as well as being involved in projects concerning the optimization of the efficacy of deep brain stimulation.

The Section for Movement Disorders and Neurostimulation collaborates with several other research groups at the University Medical Center Mainz: Department of Neurology (Neuroimmunology, Birklein), with the Neuroimaging Center Mainz (NIC), German Resilience Center (DRZ), the Emotion regulation und Impulse Control group (ERIC) of the Psychiatric Clinic (PD Dr. med. Tüscher) and the Molecular Imaging and Optogenetics group (Institute for microscopic Anatomy und Neurobiology, Prof A. Stroh).



PhD Kandidaten


Assistant Prof. Dr. Ing Muthuraman Muthuraman

National and international collaboration with the following institutes and groups:
-    Prof. G: Deuschl, Neurological Clinic, Kiel
-    Prof. J. Volkmann, Clinic, Würzburg
-    Prof. H. Siebner, Centre for Functional and Diagnostic Imaging and Research, Danish Research Centre for Magnetic Resonance


  1. Non-invasive neurostimulation. Transcranial magnetic stimulation (TMS) represents a methodology in which nerve and muscle cells can be contactlessly and painlessly stimulated via the induction principle. The methodology is employed to analyze and modulate cortical excitability, and using multifocal TMS, connectivity studies can be conducted.
  2. Deep brain stimulation: Studies of the systemic mechanisms of deep brain stimulation treatment in patients with movement disorders (incl. Parkinson's and essential tremor) are being carried out. The goal is to improve the clinical effect and reduce the possible side effects after an optimized implantation of the stimulation electrodes on the basis of the connectivity determined using magnetic resonance imaging.
  3. Structural magnetic resonance tomography data are evaluated  using diffusion-weighted imaging techniques, probabilistic tractography (FSL, SPM, VBM) as well as T1 images (Freesurfer, SPM) to perform network characterizations (BCT, NBS) and connectivity analyses.
  4. Transcranial direct-current stimulation (tDCS) is used to modulate the cerebral excitability as part of studies to trigger plasticity changes.
  5. EEG analyses (event-related potential, slow brain potential, as well as lateralization, time and frequency spectral analyses, including EEG-EEG and EEG-EMG coherence and power measurements) are employed for the imaging of cortical correlates. Simulataneous TMS-EEG techniques are applied to monitor changes in oscillatory activity.
  6. Neuropsychological investigative strategies (selection and reaction-time tasks, continuous and intermittent acoustic or visual stimulation) are being developed to modulate and measure sensorimotoric, eye-hand and cognitive processes.
  7. Kinematic measurements are applied for gathering data on bodily movements.

Selected Publications

Fleischer V, Groger A, Koirala N, Droby A, Muthuraman M, Kolber P, Reuter E, Meuth SG, Zipp F, Groppa S. (2016) Increased structural white and grey matter network connectivity compensates for functional decline in early multiple sclerosis. Mult Scler. doi: 10.1177/1352458516651503 [Epub ahead of print]


Groppa, S., J. Herzog, D. Falk, C. Riedel, G. Deuschl, and J. Volkmann. 2014. Physiological and anatomical decomposition of subthalamic neurostimulation effects in essential tremor. Brain 137: 109-121.

Hanganu, A., S. A. Groppa, G. Deuschl, H. Siebner, F. Moeller, M. Siniatchkin, U. Stephani, and S. Groppa. 2014. Cortical Thickness Changes Associated with Photoparoxysmal Response. Brain Topogr.

Groppa, S., M. Muthuraman, B. Otto, G. Deuschl, H. R. Siebner, and J. Raethjen. 2013. Subcortical substrates of TMS induced modulation of the cortico-cortical connectivity. Brain Stimul 6: 138-146.

Groppa, S., N. Werner-Petroll, A. Munchau, G. Deuschl, M. F. Ruschworth, and H. R. Siebner. 2012. A novel dual-site transcranial magnetic stimulation paradigm to probe fast facilitatory inputs from ipsilateral dorsal premotor cortex to primary motor cortex. Neuroimage 62: 500-509.

Groppa, S., B. H. Schlaak, A. Munchau, N. Werner-Petroll, J. Dunnweber, T. Baumer, B. F. van Nuenen, and H. R. Siebner. 2012. The human dorsal premotor cortex facilitates the excitability of ipsilateral primary motor cortex via a short latency cortico-cortical route. Hum Brain Mapp 33: 419-430.

Groppa, S., A. Oliviero, A. Eisen, A. Quartarone, L. G. Cohen, V. Mall, A. Kaelin-Lang, T. Mima, S. Rossi, G. W. Thickbroom, P. M. Rossini, U. Ziemann, J. Valls-Sole, and H. R. Siebner. 2012. A practical guide to diagnostic transcranial magnetic stimulation: report of an IFCN committee. Clin Neurophysiol 123: 858-882.

Depienne, C., M. Cincotta, S. Billot, D. Bouteiller, S. Groppa, V. Brochard, C. Flamand, C. Hubsch, S. Meunier, F. Giovannelli, S. Klebe, J. C. Corvol, M. Vidailhet, A. Brice, and E. Roze. 2011. A novel DCC mutation and genetic heterogeneity in congenital mirror movements. Neurology 76: 260-264.

Groppa, S., T. O. Bergmann, C. Siems, M. Molle, L. Marshall, and H. R. Siebner. 2010. Slow-oscillatory transcranial direct current stimulation can induce bidirectional shifts in motor cortical excitability in awake humans. Neuroscience 166: 1219-1225.

Groppa, S., H. R. Siebner, C. Kurth, U. Stephani, and M. Siniatchkin. 2008. Abnormal response of motor cortex to photic stimulation in idiopathic generalized epilepsy. Epilepsia 49: 2022-2029.

Siniatchkin, M., S. Groppa, B. Jerosch, H. Muhle, C. Kurth, A. J. Shepherd, H. Siebner, and U. Stephani. 2007. Spreading photoparoxysmal EEG response is associated with an abnormal cortical excitability pattern. Brain 130: 78-87.

Research Group
Movement Disorders and Neurostimulation

Group Leader
Prof. Sergiu Groppa
Department of Neurology
Langenbeckstr. 1
55131 Mainz