Your Resource for Training and Technical Support
If you need immediate assistance, call us at 1-800-970-6670 or email support@magstimegi.com.

The 10-20 system is an internationally recognized method that describes EEG electrode locations on the head surface in terms of inter-electrode distances relative to distances between cranial landmarks over the head surface.

The primary purpose of the 10-20 system is to provide a reproducible method for placing a standard number of EEG electrodes (typically 21) so that comparisons can be made across EEG studies and also between subjects.   If more electrodes are placed, the inter-electrode distances decrease, and therefore derivatives of the 10-20 system exist to account for this, including the 10-10 and 10-5 systems.

When using an electrode placement system other than the 10-20 system, such as the fast application of electrodes using the HydroCel Geodesic Sensor Net, it is sometimes necessary to relate your dense array EEG study back to a classic EEG study where the 10-20 system was used. 

To help you achieve this, you can refer to the "Determination of the HydroCel Geodesic Sensor Nets' Average Electrode Positions and Their 10-10 International Equivalents". This Technical Note published by EGI describes the average electrode positions for the 128- and 256-channel HydroCel GSN approximate the correspondence between the international 10-10 system elecrode positions with the sensors on the 128- and 256-channel HydroCel GSN.