Which test records the brain's electrical activity?

• A. ECG
• B. EEG
• C. ERCP
• D. Endoscopy

Answer: (B)

Recording the brain’s electrical activity is done with an EEG. It uses sensors or electrodes placed on the scalp to detect the tiny voltage fluctuations produced by neuronal activity. When neurons fire, they create synchronized electrical signals that propagate to the surface of the brain and can be captured as brain waves. These waves vary in frequency and amplitude, with characteristic patterns such as alpha, beta, theta, and delta rhythms that help clinicians interpret states of wakefulness, sleep, or abnormalities. EEG is especially useful for diagnosing epilepsy, evaluating coma or brain function, and studying sleep disorders.

Other tests measure different parts of the body: an ECG records the heart’s electrical activity to assess rhythm and conduction; ERCP is an imaging procedure that uses an endoscope and contrast to visualize the bile and pancreatic ducts; endoscopy involves inserting a scope to directly view the lining of the gastrointestinal tract.