Relative to P7, where is the P9 electrode placed?

The correct answer indicates that the P9 electrode is positioned 10% lateral to the P7 electrode. In the context of the International 10-20 system used for electrode placement in electroencephalography (EEG), electrode locations are typically determined based on specific percentages of the total distance between reference points on the scalp.

Placing the P9 electrode 10% laterally from P7 follows this systematic approach to ensure consistent and standardized electrode placements across different individuals, which is critical for obtaining reliable and comparable EEG readings. Lateral placement refers to a position relative to the midline of the head, with lateral indicating a position that moves away from the center.

This systematic positioning is essential for a variety of neurological assessments, including those used in long-term monitoring, where precise electrode placement can significantly influence the quality and interpretation of the data collected.