Direct Measurement of Motor Cortical Responses to tDCS

Transcranial direct current stimulation (tDCS) has shown the potential to improve symptoms in patients with movement deficits, such as Parkinson's disease and chronic stroke. However, the effects of tDCS have so far not been proven on a wider scale due to lack of knowledge regarding exactly how tDCS works. This has limited the adoption of this potentially useful therapy for patients with Parkinson's disease, chronic stroke and other conditions affecting movement. The investigators hypothesize that by studying the effects of tDCS in subjects performing a motor task, the brain signals mediating improvements in motor control will be identified. The investigators will use both noninvasive and invasive methods to explore this hypothesis. The investigators expect this combined approach to broaden understanding of tDCS application in conditions affecting movement and possibly lead to therapeutic advances in these populations.