View source for Recommended Electrode Configurations

{{BESAInfobox
|title = Module information
|module = BESA Research Basic or higher
|version = 5.2 or higher
}}

===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.

[[File:LeftTemporalBasal.png|thumb|500px|Figure 1 EEG25 - 10-20 configuration including inferior electrodes"]]

===EEG33 - Additional 10-10 electrodes within the major squares===
To the above electrodes add the following 8 intermediate electrodes:
FC5, FC1, FC2, FC6, CP5, CP1, CP2, CP6

===EEG35 - Additional supraorbital electrodes for better EOG separation===
SO1, SO2

===EEG37 - Wider inferior coverage at interlaced 20% distances===
Continue 20% down from F7, FC5, CP5, P7 etc. and use the following 8 inferior
electrodes instead of 6:
F11, FT9, TP9, P11, F12, FT10, TP10, P12

===EEG41 – Improved frontal and occipital coverage===
Additional electrodes halfway between Fz and Fp1 / FP2 and Pz and O1 / O2:
AF1, AF2, PO1, PO2

===EEG43 – Inferior chain with 5 electrodes including A1 / A2===
F11, FT9, A1, TP9, P11, F12, FT10, A2, TP10, P12
EEG43 represents the widest coverage with relatively even spacing.

===EEG64-256===
With 64 or more channel caps it is similarly recommended to use a sufficient number
of inferior electreodes all around the head. At least 4 inferior temporal electrodes on
each side and additional electrodes above or below the eyes (outside of the cap) are
suggested.
We can recommend EGI Geodesic nets (64, 128, 256) and the equidistant EasyCap
61 with additional 3 electodes for free placement around the eyes, or EasyCap 128
with nearly equidistant electrodes.

EGI: [http://egi.com/clinical-division/clinical-division-care-center/clinical-division-dense-array-neuroimaging Dense Array EEG]

EasyCap: [http://easycap.de/easycap/english/schemae.htm EEG Recording Caps]