Recommended Electrode Configurations

General considerations

There are three important aspects for source analysis and source montages:

1) Electrodes should have equal spacing.

2) A row of inferior temporal electrodes on both sides is important to cover the lower head sufficiently, e.g. F11 (F9), A1, P11 (P9). The lower sites (F11, P11) at a 20% distance are preferable to sites at a 10% distance (F9, P9) from the standard row F7, T7, P7 (same applies to other side).

3) Electrodes should be symmetric between both hemispheres with a midline reference or an implicit reference (e.g. F3+F4). A recommended standard with 33 electrodes adds a midline reference Pz, and F11, A1, P11, FC1, FC5, CP1, CP5 and their homologues over the right hemisphere to the 19 electrodes of the 10-20 system (Fpz, Oz not included). For more details see BESA help chapter on Electrodes. When using caps with more electrodes (64 or 128) inferior electrode and equal spacing are similarly important.

In the following montage EEGxx the number xx indicates the number of electrodes.

EEG25 - Minimum 10-20 configuration including inferior electrodes

This covers the 19 standard 10-20 electrodes: Fp1, Fp2, F7, F3, Fz, F4, F8 .... plus 6 inferior electrodes on both sides: F11, A1, P11, F12, A2, P12 with a recommended continuation of the 20% distances, i.e. use F11 instead of F9, P11 instead of P9, A1 instead of T9 to have a wider coverage of the inferior head. A1 / A2 may be replaced by T9 / T10 (or FT9 / FT10) for convenience and comfort.