Simply EEGLAB

Where the EEG signal comes from

Station 0 · Lesson 1 · EEGLAB 2026.1

Script

nSources = 1000;              % number of small sources
srate    = 128;               % samples per second
t        = 0:1/srate:2;       % 2 seconds of time
f        = 10;                % frequency in Hz (alpha range)
phases   = 2*pi*rand(nSources, 1);
asyncSum = sum(sin(2*pi*f*t + phases), 1);
syncSum  = sum(sin(2*pi*f*t + zeros(nSources, 1)), 1);
fprintf('Peak of random-timing sum: %.0f\n', max(abs(asyncSum)));
fprintf('Peak of synchronized sum:  %.0f\n', max(abs(syncSum)));
figure;
plot(t, syncSum); hold on;
plot(t, asyncSum);
xlabel('Time (s)'); ylabel('Summed amplitude (a.u.)');
legend('Synchronized', 'Random timing');

Which value should I choose?

SourceDoes it show up in EEG?
Postsynaptic potentials in cortical pyramidal cellsYes, this is the main brain signal
Action potentialsAlmost never
A single cellNo
Deep brain structuresVery weak
Eye blinks and eye movementsYes, strongly
Muscles (jaw, neck, forehead)Yes
HeartSometimes
Power lineYes

Full lesson: https://simplyeeglab.pages.dev/en/lesson/eeg-origin/

Content license: CC BY-NC-SA 4.0 · MIT (code)

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