According to the 10-20 electrode placement system, where is Cz located?

The location of Cz is significant in the context of the 10-20 electrode placement system, which is a standardized method for positioning electrodes on the scalp for EEG and sleep study assessments. Cz refers to the "central" electrode, which is crucial for recording brain activity from the central region of the brain.

Cz is specifically placed at the midpoint between the two preauricular points (the points near the ears) and the nasion (the bridge of the nose) and inion (the bony prominence at the back of the skull). This positioning is critical because it allows for accurate representation of brain activity in the central line of the head.

This bipolar location helps in obtaining a neutral reference point for measuring electrical potentials and is utilized in various assessments, including monitoring during polysomnography. The precise placement ensures consistent results across different assessments and enhances the reliability of the data gathered during sleep studies.

Consequently, the choice that states Cz is located at this midpoint aligns perfectly with the established 10-20 system, making it the correct answer for this question.