Electroencephalography ( EEG ) is a method to record an electrogram of
the spontaneous electrical activity of the brain. The biosignals detected by
EEG have been shown to represent the postsynaptic potentials of pyramidal
neurons in the neocortex and allocortex. It is typically non-invasive, with
the EEG electrodes placed along the scalp (commonly called "scalp EEG") using
the International 10–20 system, or variations of it. Electrocorticography,
involving surgical placement of electrodes, is sometimes called "intracranial
EEG". Clinical interpretation of EEG recordings is most often performed by
visual inspection of the tracing or quantitative EEG analysis.