Brain cells communicate with each other by producing tiny electrical impulses. In an EEG, this faint electrical activity is measured by putting electrodes on the scalp. The test is performed by an EEG technician in your health care provider's office, at a hospital, or at a laboratory. You will be asked to lie on your back on a bed or in a reclining chair. The technician will place between 16 and 25 flat metal disks (electrodes) in different places on your scalp. The disks are held in place with a sticky paste. The electrodes are connected by wires to an amplifier and a recording machine. The recording machine converts the electrical impulses into patterns that can be seen on a computer screen and stored on a computer disk. Before computers, the activity was printed on paper. In either case, the electrical activity looks like a series of wavy lines. You will need to lie still with your eyes closed because any movement can change the results. You may be asked to do certain things during the recording, such as breathe fast and deeply for several minutes or look at a bright flashing light.

Brain cells communicate with each other by producing tiny electrical impulses. In an EEG, this faint electrical activity is measured by putting electrodes on the scalp. The test is performed by an EEG technician in your health care provider's office, at a hospital, or at a laboratory. You will be asked to lie on your back on a bed or in a reclining chair. The technician will place between 16 and 25 flat metal disks (electrodes) in different places on your scalp. The disks are held in place with a sticky paste. The electrodes are connected by wires to an amplifier and a recording machine. The recording machine converts the electrical impulses into patterns that can be seen on a computer screen and stored on a computer disk. Before computers, the activity was printed on paper. In either case, the electrical activity looks like a series of wavy lines. You will need to lie still with your eyes closed because any movement can change the results. You may be asked to do certain things during the recording, such as breathe fast and deeply for several minutes or look at a bright flashing light.