A material that does not easily transmit energy, such as electric current or heat. Materials such as wood, plastic, and ceramics are insulators. Fiberglass is an example of a heat insulator. (Compare conductor.)
An electroencephalogram (EEG) is a noninvasive test that records electrical patterns in your brain. The test is used to help diagnose conditions such as seizures, epilepsy, head injuries, dizziness, headaches, brain tumors and sleeping problems.
The electroencephalogram (EEG) is a measure of brain waves. It is a readily available test that provides evidence of how the brain functions over time. 1  The EEG is used in the evaluation of brain disorders. 2  Most commonly it is used to show the type and location of the activity in the brain during a seizure. The EEG is used in the evaluation of brain disorders. 2  Most commonly it is used to show the type and location of the activity in the brain during a seizure. 3  It also is used to evaluate people who are having problems associated with brain function.