Determining the Specificity of High Definition Electrical Brain Stimulation Using Simultaneous Magnetoencephalography

Non-invasive human brain stimulation using weak transcranial direct-current stimulation (tDCS) has been thousands of times in research studies over the past fifteen years as a therapy to help improve the effectiveness of repeated training sessions (e.g., hand exercises in the context of daily physiotherapy), due to its safety, tolerability, convenience and cost-effectiveness. tDCS works by temporarily enhancing brain activity during performance of a specific task, helping with learning and training. The investigators will use magnetoencephalography (MEG) brain imaging to view the real-time effects of high definition (HD) tDCS on several brain areas involved in vision, hearing, movement, and memory. The investigators hypothesize that changing the task (auditory, visual or memory task) but keeping the position of the electrodes over the motor cortex will result in modulation of brain activity in only the central target motor area, and not on non-target temporal, occipital or pre-frontal areas.