In the 10-20 system, what percentage do the parasagittal planes Fp1 to O1 and Fp2 to O2 divide into?

In the 10-20 electrode placement system used in electroencephalography (EEG), the parasagittal planes represented by the electrode placements from Fp1 to O1, and Fp2 to O2, divide the head into specific regions that correspond to percentages based on the distribution of the electrodes.

The correct percentage for the division created by the Fp1 to O1 and Fp2 to O2 planes is indeed 25%. This percentage corresponds to the proportion of the total head surface area that is represented by these specific electrode positions. In the context of the 10-20 system, these points are integral for localizing brain activity across specific regions, and the 25% division emphasizes the importance of capturing data from a significant portion of the cerebral hemispheres, which is critical for accurate neurophysiological assessment.

Understanding how these segments exemplify the 10-20 system's systematic approach to brain mapping can aid in the identification and evaluation of various neurological disorders, ensuring that data collection is consistent and standardized across different evaluations.