In this study, EEG/MEG coherence analysis will be used to investigate corticocortical and corticomuscular interactions during voluntary hand movements in focal hand dystonia patients and normal subjects. Power spectral changes in the beta and alpha frequency range over the hand sensorimotor cortex will be studied using a 28-channel EEG montage while subjects perform various tasks involving the hand. The interregional coherence between sensory and motor, premotor and motor, and interhemispheric cortices will be assessed for changes between study populations.