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.
1). Figure 1. A sample EEG recording showing a focal spike typical of a seizure. There are several different ways to conduct an EEG: 1  Standard EEG recording is done in the office and usually lasts an hour. 2  You may be asked to do a sleep-deprived EEG, which requires you to have only 4 hours of sleep.Abnormal brain waves may appear when the body is stressed or fatigued. This exam usually takes 2 to 3 hours. You will be given specific instructions regarding food, drink, and medications that may need to be avoided.). Figure 1. A sample EEG recording showing a focal spike typical of a seizure. There are several different ways to conduct an EEG: 1  Standard EEG recording is done in the office and usually lasts an hour. 2  You may be asked to do a sleep-deprived EEG, which requires you to have only 4 hours of sleep.