What tests show the brain's electrical activity?

• Electroencephalogram (E.E.G.) - Small metal disks (electrodes) are placed at strategic locations on a person's scalp. The electrodes can detect the electrical activity in the form of impulses that are then transcribed to paper. By observing such impulse characteristics as intensity (the size of the impulse), duration (the width of the impulse), frequency (how often impulses occur during a given time) and location (what region of the brain produces these impulses), an EEG can provide valuable information about underlying problems in the brain.


• Evoked response test - A diagnostic procedure that provides a measurement of the brain's ability to process and react to different sensory stimuli. A doctor evokes a visual response by flashing a light or checkerboard pattern in front of a patient. For auditory evoked responses, a doctor produces a sound in one of the patient's ears. For bodily evoked responses, one of the nerves in an arm or leg is electrically stimulated. The responses from these sensory stimuli can indicate abnormal areas of the brain.