Which EEG electrode is located halfway from F8 to Fz?

The correct answer is F4, as it is the electrode that is positioned halfway between F8 and Fz. In the international 10-20 system of electrode placement, F8 is located at the right frontal area, while Fz is situated at the midline of the frontal region. The F4 electrode is specifically placed in the right frontal area, making it equidistant from both F8 and Fz. Understanding electrode placement is crucial in polysomnography, as it provides essential information about brain activity during different sleep stages and assists in diagnosing sleep disorders.

The other options represent different electrodes in the 10-20 system. Fz is the midline frontal electrode itself and not an intermediary position. Fp1 is located at the left prefrontal area, while Pz is situated at the midline parietal area, both of which are not positioned between F8 and Fz. Therefore, F4 is the only electrode that accurately fits the requirement of being halfway between F8 and Fz.