Source derivation recordings of generalized spike-wave complexes.

The effects of the reference electrode on field changes during generalized spike-wave complexes were studied. Linked ears reference, common average reference and source derivation were compared. Source derivation proved superior to the common average reference because it was not influenced by the 'dipole' effect when large transients are distributed over all the electrodes. Source derivation retained the midfrontal field maximum as previously reported but also showed more frequent bilateral onset. Furthermore, it revealed the marked participation of temporal structure and enhanced biparietal or Pz components. The typical appearances of the maps are demonstrated and the implications discussed.