EEG is a bio- medical process of recording minute electric currents produced by the brains of hunan beings. this was discovered by Hans Berger of Jena(now in East Germany) in 1929,and found to have important clinical significance in the diagnosis of brain diseases.
The brain constantly generates minute electrical currents even during sleep and deep coma.these can be recorded from the skulls surface by means of small wires(electrodes) attached to the scalp.In normal persons they have an electrical potential of about 100 microvolts.
In the normal adult person most of the EEG recordings are made up of rhythmic oscillating waves regularly repeated at about 10 Hertz.They are called alpha waves.They are best obtained from the back of the central nervous system when a person is in a relaxed position with the eyes closed.The waves disappear or are blocked when the eyes are opened.
The irregular slow waves (one to three per second) that arise from the localized area of brain damage are called delta waves. Rhythmic slow waves at frequencies between 4 and 7 Hertz are called theta waves.
It has proved helpful in detecting many brain diseases. Epilepsy and abnormal metabolic conditions can be detected through it.'coma' conditions can be studied from EEGs.If we get a flat EEG it indicates the ' brain death '.
Epilepsy is diagnosed through this EEG. Other brain disorder can also be diagnosed through it by sending electrical impulse in the brain.