Which of the following sites is most commonly used for the ground electrode in EEG?

The site most commonly used for the ground electrode in EEG is FPz. This location is situated on the forehead, at the midline between the eyes and the hairline. Using FPz as the ground electrode is advantageous because it provides a stable reference point that minimizes noise and interference from other electrical activity. Its placement allows for minimal impact on the overall recording and maintains a clean signal from the other electrodes.

In EEG practice, the ground electrode is crucial as it helps to stabilize the electrical readings and reduce the influence of common electrical interference, such as power line noise. FPz is also relatively distant from the areas where the brain activity of interest is measured, thus ensuring that it does not influence the readings significantly.

Other sites mentioned like Pz, Oz, and Fz are all active recording sites placed on the scalp for monitoring specific brain activity but are not utilized as ground electrodes due to their proximity to primary recording sites, which could lead to signal contamination and inaccurate readings.