I. INTRODUCTION
Neuroplasticity or cortical reorganization allows the brain to adapt itself and to relearn functions lost in a brain area due to an incident (e.g. after stroke). There is evidence that therapeutic training stimulates cortical reorganization [1] and helps to restore motor function. Key factors for an effective therapy are task-specific training [2], high intensity and duration, many repetitions of the training [3]–[5], active participation of the patient [6], [7], maximal challenge for the patient [6] and execution of complex movements [8].