Wednesday, December 21, 2005


Human brain normally operates within a range from 1 to about 40 Hz. ( 0.16 Hz to 35 Hz in -6 dB : standard EEG amplifier filter specification )

for the purpose of EEG (electroencephalogram) analysis and clinical description, the frequency band has been divided into a number of so-called rhythm.

Richard Caton of England showed as early as 1875 that waves of electrical activity can be record from the surface of the brains of animals, but this finding lay unnoticed until the work of Hans Berger, of Germany, in the 1920s.

Berger was a psychiatrist, and also served as Rector of the University of Jena.

His main research interest was determining what he called the physical basis of psychic function.

Berger's report in 1929 that electrical waves could be recorded from the scalp, subject was his young son.

These early studies established that the dominant rhythm in the resting subject is 8-13 Hz, and is most prominent when the recording leads are over the occipital lobe of the brain (where the primary visual cortex is located).

This is called Berger rhythms, now called it Alpha rhythm.


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