An embodiment in accordance with the present invention is directed to a system and device for applying electrical direct current transcranially to the brain that is combined with a behavioral activity consisting of an isometric force production task. The device is non-invasive or implantable and serves to improve motor symptoms in Parkinson's disease (PD) and other movement disorders. During the stimulation, the patient is engaged in a behavioral task using a system consisting of two force transducers and a controller. The patient holds the transducers, one in each hand, and is engaged in a task that requires the brain to assign forces to each arm so that the sum of the forces matches an instructed amount. In an electrode placement specifically for PD, bilateral primary motor cortices are simultaneously stimulated according to a specific algorithm that depends on the forces that the PD affected individual produces in the behavioral task.
