Psychophysische und neurophysiologische Korrelate übungsinduzierter kortikaler Veränderungen in der Fokalen Handdystonie als Modell von Gehirnplastizität beim Menschen

Cortical plasticity appears to be involved in the etiology of focal hand dystonia, a very often task-specific sensorimotor disorder. The simultaneous two-point finger discrimination of some affected patients was evaluated. Dystonic musicians showed loss of perceptual symmetry between dystonic and non-affected hands. These changes were specific to their dystonic zones. Homologous asymmetries were not observed in writer s cramp, another form of focal hand dystonia. Using Magnetoencephalography (MEG), a smaller distance between the representations of the digits in the somatosensory cortex of the affected hand of dystonic musicians compared to the hands of non-affected individuals was demonstrated. A behavioral intervention produced long-term reduction of symptoms in some affected musicians, and their subjective ratings were highly correlated with objective data depicting changes in smoothness of finger movements. Pre- to post-treatment changes in somatosensory cortex were measured using whole head MEG. It was found that effective treatment with Sensory Motor Retuning (SMR) leads to alterations in functional organization of the somatosensory cortex. After treatment, somatosensory relationships of the individual fingers of the affected hand were similar to the non-affected side, and more ordered according to homuncular principles. The observed physiologic changes correlated with behavioral data obtained with a displacement dexterity device. These results confirmed that sensory anomalies are associated with focal hand dystonia and extend far beyond of the affected task. Cortical changes in parallel with emergent neurological dysfunction may be reversed by context specific intensive training protocols. It was demonstrated that cortical plasticity in response to behavioral interventions can be successfully assessed using non-invasive neuroimaging techniques. Some possible mechanisms of cortical plasticity mediating all of the observed changes were discussed