The practice of placing electrodes on a subject’s scalp in order to non-invasively measure the electrical activity of the brain. This process is used to determine if someone has a issue with their brain. Usually, the EEG is used to try and locate the causes of seizures, but it can be used to try and find the causes of other issues like comas, tumors, confusion, strokes, and memory problems.
Example: Researchers in a sleep lab spend the semester recording the EEG activity of both insomniac and normal subjects in order to learn more about sleep disorders.
To read about how to prepare to have an EEG, see risks associated with the procedure etc, please follow this link: http://www.emedicinehealth.com/electroencephalography_eeg/article_em.htm