Homeostatic plasticity of the motor cortex is impaired in focal dystonia

Background: In patient with writer's cramp, the excitability of inhibitory circuits has been shown to be reduced at multiple levels within the sensorimotor system, including the primary motor hand area (M1). Though deficient sensorimotor inhibition is thought to play a major role in the pathophysiology of writer's cramp, it is unclear which mechanisms lead to an imbalance in regional excitability. One possibility is that homeostatic mechanisms which keep cortical excitability levels within a normal physiological range are impaired in focal hand dystonia. Methods: In eight patients with writer's cramp and eight h…