What does electroencephalography measure?

• A. Brain electrical activity
• B. Heart rate variability
• C. Blood oxygen levels
• D. Muscle contraction signals

Answer: (A)

Electroencephalography (EEG) is a diagnostic tool specifically designed to measure the electrical activity of the brain. It does this through electrodes placed on the scalp, which detect the electrical impulses produced by neuronal activity. This technique is crucial for diagnosing and monitoring various neurological disorders, such as epilepsy, sleep disorders, and other conditions affecting brain function.

Understanding the nature of EEG helps clarify why the other options do not apply. For instance, heart rate variability pertains to the fluctuations in the intervals between heartbeats and is typically assessed using electrocardiography (ECG). Blood oxygen levels are measured through pulse oximetry or arterial blood gas analysis, neither of which involve direct assessment of brain activity. Muscle contraction signals, on the other hand, are evaluated using electromyography (EMG), which focuses on the electrical activity of muscle fibers, not the brain. Thus, the correct answer accurately reflects the primary function of electroencephalography in the field of medical diagnostics.