Simulation
Before it's built.
What 1,118 dry contacts would pick up, simulated from real EEG.
No exocortex has been built or measured yet. Everything on this page is a simulation.
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Listen in.
40 seconds of a real resting recording, re-sampled onto the cap and run through the hat's electronics in simulation. The eyes close at 12 s: alpha, 8–13 Hz, rises over the back of the head. Blinks show on the front contacts. Switch to raw to see the mains.
Each trace is one contact's simulated output, referred to the input: the recording's EEG through that contact's impedance, the input divider and the amplifier, with its noise, the mains and the converter added. Named for the nearest 10-20 position. The model's slow drift of each contact's skin potential is left out, as it is from the noise figures. Tap a ringed contact on the head to add it.
Alpha, beta, theta. Across the head.
Power in each band at every contact, every half second, from the same 40 seconds. Seen from above, nose up. Eyes open, then closed.
Each frame is the power in a 2 s window of the hat's simulated output, in dB re 1 µV², averaged over the contacts within about 8 mm of each, on one colour scale per band for the whole scene. The black dot is REF.
A simulation, not a measurement.
No exocortex has been built. The EEG on this page is real: public recordings from other systems, re-sampled onto our 1,118 contact sites. Everything between the scalp and the numbers is a model: dry-contact impedance through hair, the input network, the amplifier and converter noise, and the interference worked out from the boards' own geometry. The re-sampling cannot add detail finer than the source montage, so fine spatial structure comes from the forward model only.
Simulated with the design as drawn (gain 101, 10 MΩ bias, 220 nF coupling, 12-bit converters at 64× oversampling). Gold EEG: the Healthy Brain Network (CC BY-SA 4.0), OpenNeuro ds004148 (CC0) and the Lee & Ahn DSI-24 set (CC BY 4.0). Cortex and lead field: FreeSurfer fsaverage with MNE-Python's BEM. The wearer's head: MakeHuman (CC0); skull: BodyParts3D (CC BY 4.0). exocortex is not a medical device and is not for diagnosing, treating or monitoring any condition.