Extracting signals from the brain is mainly used to help people with severe motor disabilities resulting from locked-in syndrome, cerebral palsy, muscular dystrophies, spinal cord injuries, brainstem strokes or similar conditions. But there are efficacy problems which have to do with the resolution of brain signals. This means that scalp readings which are non-invasive give a low resolution of signals which limits their efficacy, whereas invasive implants, e.g., onto the surface of the brain, provide a much higher resolution. The latter however, introduce similar kinds of safety concerns as those associated with deep brain stimulation and invasive neural prosthesis in general.