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Electrode definition in ELAN (elec.dat)

ELAN is provided with a long list of electrodes (10/20 and extended systems) that cover most of the classically used electrode montages. The users can extend this list. The characteristics of the electrodes are specified in a text file created when installing ELAN: elec.dat in the directory $ELANPATH/elec (for example /usr/local/Elan/elec). Each entry of this file corresponds to a particular electrode with a number, a name and spherical coordinates (theta and phi) on a unit sphere mimicking the head (see figure below).

Within ELAN, all electrodes will be identified by their number (according to their rank in elec.dat) and/or names.

This elec.dat file is thus critical and should be modified with care.

We highly recommend not to delete any existing entry in elec.dat, but only to add new entries at the end of the file with a similar format.

The file elec.dat has the following structure:

column 1: electrode number, columns 2, 3: theta, phi in degrees, column 4: electrode name

1 90.0 252.0 O1

2 90.0 288.0 O2

3 90.0 216.0 T5

4 63.1 223.1 P3

5 45.0 270.0 Pz

6 63.1 316.9 P4

7 90.0 324.0 T6

8 90.0 180.0 T3

9 45.0 180.0 C3

10 0.0 0.0 Cz

 

11 45.0 0.0 C4

12 90.0 0.0 T4

13 90.0 144.0 F7

14 63.1 136.9 F3

15 45.0 90.0 Fz

16 63.1 43.1 F4

17 90.0 36.0 F8

elec.dat axis

18 90.0 108.0 Fp1

19 90.0 72.0 Fp2

20 76.5 219.3 P5

……….