An EEG is a test that is used to measure and analyze the electrical activity of the brain. It is very important in determining various aspects of neural activity, such as if there is an over activity in any areas of the brain, which could lead to seizures. In the cases of stroke, it is more importantly used to recognize any abnormal inactivity in the brain, which could identify any dead tissue.
During an EEG you will have various electrodes placed on very specific areas on your scalp. These electrodes will be used to conduct the electrical activity at various parts and along various pathways throughout the brain. In some cases, you may wear a cap that already has the electrodes attached to them. Prior to undertaking an EEG, avoid using any hair products after washing your hair, as the substances in the products may interfere with the electrical recording from the electrodes.