Electroencefalograpy (EEG) is the recording of intrinsic electrical activity in the brain, based on the propagation of electric impulses along a nerve fibre when the neuron fires. EEG is typically analyzed in frequency bands that correspond to different mental states, e.g. is the alpha-frequency (8-13 Hz) associated with a relaxed mental state. By recording small potential changes in the EEG signal immediately after the presentation of a sensory stimulus it is possible to record specif brain responses to specific sensory, cognitive and other mental events. This method is called Event-Related Potentials (ERPs) and is one of the classic methods for investigation of psychophysiological states and information processing.


Typical electrode montage for EEG/ERP recordings (mid-picture) and examples of EEG tracings separated for different frequency bands (left picture) and ERP tracings to repeated auditory stimuli (right picture).