Royalty free and rights managed images relating to electroencephalography (EEG). This technique uses electrodes to record the electrical field produced by brain activity. The output is known as an electroencephalogram. This section includes illustrations of brainwaves and conceptual images showing electrical waves produced by the brain. Photographs and pictures show scientists carrying out EEG research on sleep (circadian rhythms), thought-controlled wheelchairs, and conditions such as epilepsy.