Neurophysiology of Movement DisordersNeurology Research Group Freiburg
A basic issue in the neurophysiology of motor control is how the brain generates the complex spatiotemporal commands needed to vary speed, amplitude, and direction of finger movements. Surround inhibition is a physiological mechanism to focus neuronal activity in the central nervous system. This so-called center-surround organization is well-known in sensory systems, where central signals are facilitated and eccentric signals are inhibited in order to sharpen the contrast between them. There is evidence that this mechanism is relevant for skilled motor behaviour, and it is deficient, for example, in the affected primary motor cortex of patients with focal hand distonia (FHD).
While it is still not fully elucidated how surround inhibition is generated in healthy subjects, the process is enhanced with handedness and task difficulty indicating that it may be an important mechanism for the performance of individuated finger movements. In FHD, where involuntary over-activation of muscles interferes with precise finger movements, a loss of intracortical inhibition likely contributes to the loss of surround inhibition. Several intracortical inhibitory networks are modulated differently in FHD compared to healthy subjects, and these may contribute to the loss of surround inhibition.
Surround inhibition can be observed and assessed in the primary motor cortex. It remains unclear, however, if the effects are created in the cortex or if they are derived from, or supported by, motor signals that come from the basal ganglia.
Current projects aim to better understand the underlying mechanisms of surround inhibition in healthy volunteers, but also in other types of focal and generalized dystonia, using different electrophysiological techniques. The main research topics are dystonia and transcranial magnetic stimulation.
Surround inhibition in other types of focal dystonia.
Transcranial magnetic stimulation (TMS) and other electrophysiological devices.
Coordinator: PD Dr. Sandra Rutsch
Group Member: Anne Hartmann
- Prof. Dr. Albert Gollhofer / Dr. Christian Leukel, Department of Sport Science, University of Freiburg, Germany
- Prof. Mark Hallett, National Institutes of Health, National Institute of Neurological Disorders and Stroke, Human Motor Control Section, Bethesda, USA
- Dr. Elise Houdayer, Divisioni, Centri, Istituti e Programmi di Ricerca, Human Brain Invivo Mapping with Neuroimaging (BRAINMAP), Milano, Italy
- Dr. Sarah Pirio Richardson, Department of Neurology, University of New Mexico, Albuquerque, New Mexico, USA
- PD Dr. Martin Schubert, Spinal Cord Injury Centre, University Hospital Balgrist, Zürich, Switzerland
- Dr. Wolfgang Taube, Department of Medicine, Movement and Sport Science, University of Fribourg, Switzerland