Dystonia encompasses a group of movement disorders characterized by involuntary muscle contractions causing twisting and repetitive movements and abnormal postures. In the recent past, novel insights from both genetic discoveries and functional studies from patients with dystonia have improved our understanding of the pathophysiology of this disorder. Similarly, characterization of animal models helped deciphering the circuits and molecular pathways involved in its pathogenesis. In particular, compelling evidence obtained from both clinical and experimental studies converge on the identification of three main neurophysiological correlates sustaining the pathophysiology of the disease: loss of inhibition within the sensorimotor circuitry, disrupted sensorimotor integration, and maladaptive homeostatic plasticity. In the background, the interaction between cholinergic and dopaminergic transmission appears increasingly relevant. This chapter will focus on findings from both human and animal studies of functional brain alterations underlying changes in sensorimotor circuits associated with motor learning and memory, leading to such a disabling motor disorder.