The electrical activity of the brain is recorded as an?

• A. Electrocardiogram
• B. Angiogram
• C. Electromotor response
• D. Electroencephalogram

Answer: (D)

Electrical activity produced by neurons in the brain is recorded with an electroencephalogram, which uses electrodes placed on the scalp to detect the tiny voltage changes generated by ionic currents during neural firing. The resulting EEG traces reflect the summed activity of large groups of neurons, especially those in the cortex, and are widely used to study brain states, sleep, and seizures, among other things. This is why the electroencephalogram is the correct choice.

The other options don’t measure brain electrical activity: the electrocardiogram records heart electrical activity; an angiogram visualizes blood vessels using contrast; and electromotor response isn’t a standard tool for recording brain electrical signals.