Source Derivation Recordings for Cerebral Electrical Topography

ABSTRACT.

Cerebral electrical field maps are based most commonly on a referential montage which frequently uses linked ear electrodes as the reference. Since this electrode combination is not necessarily electrically neutral, difficulties in interpretation of the maps can arise, especially when frequency analyses are being performed. This manuscript points out the problems which can be encountered with the linked ears montage and shows the results when the same data are changed to the common average reference or to source derivation. A brief technical description and explanation of the latter methodology is given and examples are provided to demonstrate that it has the best discriminating power by giving the most discrete focal fields. The possibility of determining the relative depth of a given EEG signal by judicious combination of average reference recordings and source derivation is also presented.

KEY WORDS.:

• EEG
• source derivation
• topography