Topographic mapping of EEG artifacts.

The topographic distribution of the artifacts of gritting the teeth, eye movements and blinking were studied in 32 channel recordings. In records from resting normal controls with all artifacts deleted, little EEG activity is present below 1.2 Hz or above 22 Hz. Gritting the teeth does not produce any apparent artifact in the alpha band or lower frequencies. However, it increases fast activity at 13 Hz and above across the scalp, especially in the temporal region bilaterally. The activity of eye movements was strongly present in low frequency maps in the frontal area and disappeared above 9 Hz. Blinking influences all four frequency bands greatly. Knowledge about the frequency range within the power spectrum and the areas on the map in which artifact appear is important in interpreting clinical EEG maps.