There will be one main study and one exploratory study with similar designs; the former will explore the parieto-motor network (PAR study) and the latter, the cerebello-motor network (CER study). There will be two independent arms in each study: one will compare patients with writer s cramp (WC) and age-matched healthy volunteers (HV); and the other one will compare patients with cervical dystonia (CD) with age-matched HVs. The power analysis of the main (PAR) study indicates that we need to enroll 17 patients and 17 healthy volunteers in each arm, with an additional 3 added to account for drop-outs. Therefore, we request a maximum of 20 subjects per patient group and 40 subjects for the control groups. A second power analysis for the exploratory CER study indicates that we need to enroll 13 healthy volunteers and 13 patients in each arm, with an additional 3 added to account for drop-outs. Thus, we request a maximum of 16 subjects per patient group and 32 subjects in the control groups.