A better understanding of the disorder requires significant improvements of its phenomenological description in relation to aetiology. We want to identify specific motor signatures of different forms of dystonia. To that aim, we will ask patients to perform movements of various complexities, while recording chronometric, kinematics and EMG data. The characteristics of the patients' movements will be compared to those of matched control subjects. We will examine abnormal co-activation in distal and proximal muscles to evaluate the characteristics of the loss of selectivity of the motor command in mobile vs. fixed dystonia. Consistency of the motor output patterns will be compared in three groups of patients. We will also study possible cognitive and limbic components of the disease, examining the influence of cognitive and emotional loads on movement production. Eventually we want to refine the criteria used to classify different forms of the disease, thus enabling clinicians to better predict the likely outcome of particular therapeutic procedures.