Brain-activated technology. Three maps of brain electrical activity at a frequency of 11 Hz (cycles per second) showing a subject controlling a computer by thought. The movement of a cursor on a computer screen is controlled by the intensity of brain activity at this frequency. At top left, the subject is commanding the cursor to move upward, at top right the subject is commanding the cursor downward. At bottom, the cursor is not being displayed to the subject. Note that the intensity of activity in the left mid part of the scalp is raised (more red/orange) or suppressed to command cursor movement.