An electroencephalogram is used to:

• A. measure heart function
• B. measure liver enzymes
• C. measure brain function
• D. measure blood pressure

Answer: (C)

An electroencephalogram measures brain function by recording the brain’s electrical activity through electrodes placed on the scalp. The brain’s neurons generate electrical signals that show up as wave patterns, which clinicians analyze for things like seizures, sleep stages, or levels of consciousness. This test does not assess heart function (that’s done with an electrocardiogram), liver enzymes (measured in blood tests), or blood pressure (measured with a cuff or arterial line). So EEG is specifically used to evaluate brain activity.