What is an electroencephalogram (EEG) used to measure?

An electroencephalogram (EEG) is a diagnostic tool specifically designed to measure the electrical activity of the brain. It does this by placing electrodes on the scalp, which detect voltage fluctuations resulting from the activity of neurons in the brain. The EEG provides real-time data on brain wave patterns, helping clinicians assess various neurological conditions, such as epilepsy or sleep disorders.

This focus on electrical activity distinguishes the EEG from other methods of brain measurement. For instance, tools like fMRI or PET scans are geared towards measuring blood flow or metabolism, which relate to oxygen consumption and overall brain function in a different context. Consequently, while options that mention blood flow, oxygen consumption, and medication effectiveness are important aspects of neurological research, they do not pertain directly to the primary function of an EEG. The EEG's unique ability to assess and record electrical patterns is what makes it the correct answer to the question.