Neurofeedback is based on two basic concepts. The first is that we can measure the electrical activity of the brain and that this activity reflects mental states. The second is that this activity can be improved with training.
Neurofeedback uses an instrument called an EEG (electroencephalogram) to monitor brain electrical activity. Advances in computer technology have made it possible to convert EEG data into images and sounds that can be displayed to the user in real time. As the user alters their own mental state they change the amplitudes of various brainwave frequencies. The user sees this change as it is reflected on the displays and attempts to alter their brainwave patterns to achieve a predefined goal. In this manner the user learns to self-regulate their own brainwave patterns, and therefore their own mental states which produced those patterns.