Simply EEGLAB

The 10-20 system & electrodes

Station 0 · Lesson 2 · EEGLAB 2026.1

Script

eeglab nogui;                                         % load EEGLAB functions only
eeglabRoot = fileparts(which('eeglab'));
locs = readlocs(fullfile(eeglabRoot, 'sample_data', 'eeglab_chan32.locs'));
figure;
topoplot([], locs, 'style', 'blank', 'electrodes', 'labelpoint');
title('eeglab\_data.set montage');
disp({locs.labels});                                  % list all channel names

Which value should I choose?

Letter	Region	Example
Fp	Front of the forehead, above the eyes (frontopolar)	Fp1, Fp2
F	Frontal lobe	F3, Fz
C	Central area around the central sulcus. Not a separate lobe	C3, Cz
T	Temporal lobe	T7, T8
P	Parietal lobe	P3, Pz
O	Occipital lobe at the back of the head	O1, O2
Two letters	An electrode between two regions	FC5 between F and C, PO7 between P and O
Mark	Meaning	Example
Odd number	Left half of the head	C3, O1
Even number	Right half of the head	C4, O2
z	The midline from nose to back of the head (from "zero")	Fz, Cz, Pz
Larger number	Farther from the midline	C5 is farther out than C3, and C3 farther than C1
System	Idea	Where you see it
10-20	21 electrodes. Neighboring electrodes are 10% or 20% of the head length between fixed landmarks apart	Routine clinical recording
10-10	Same idea, with extra electrodes halfway along each distance, so the step is 10%	`eeglab_data.set` (32 channels), and the PhysioNet file in station 2 (64 channels)
10-5	5% steps, for high-density systems (Oostenveld and Praamstra 2001)	Systems with 128 channels or more

Script

Which value should I choose?

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