EEG - Electroencephalogram

An EEG (electroencephalogram) is a test that evaluates the brain's electrical activity. Brain cells communicate with one another through tiny electrical impulses, and an EEG tracks and records the resulting patterns as brain waves - essentially a graphical trace of the electrical activity occurring in the cortical and sub-cortical regions of the brain. To record it, surface electrodes are placed on the scalp; these electrodes pick up the brain's electrical impulses and send the signals to a computer, which displays and stores the results as a waveform. The technique traces back to 1929, when the German scientist Hans Berger became the first person to record and analyse a human EEG - which is why EEG waves are also sometimes called 'Berger waves'. The electrical activity recorded may appear as synchronised (regular, rhythmic) or desynchronised (irregular) patterns, and is conventionally described in terms of four named frequency bands or rhythms: alpha, beta, delta and theta waves, each associated with different states of alertness or sleep. Clinically, EEG is used to study how the brain functions and coordinates with the rest of the body; to help diagnose neurological and sleep disorders; as a diagnostic aid in serious head injuries, brain tumours and cerebral infections; to detect conditions such as epilepsy a …