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.
Overview. An electroencephalogram (EEG) is a test used to evaluate the electrical activity in the brain. Brain cells communicate with each other through electrical impulses, and an EEG can be used to help detect problems associated with this activity.