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		Tests for Brain, Spinal Cord, and Nerve Disorders

Electroencephalography (EEG) records electrical activity in the brain via electrodes attached to the forehead and scalp. This recording is called an electroencephalogram. The electrical activity is recorded as waves that are classified based on frequency (how fast they are), amplitude (how wide they are) and location in the brain. Letters of the Greek alphabet, such as alpha and beta, are used for the different types of waves. On the right, the electroencephalogram shows normal alpha, beta, theta, and delta waves.

(From KS Saladin: Anatomy and Physiology, WCB McGraw-Hill, 1998, p. 489; with permission.© The McGraw-Hill Companies Inc./Dennis Strete, photographer.)