EEG combined with VR

We recently had a meeting at the Astron radio telescope for the COGITO project with Daniela de Paulis, Stephen Whitmarsh, Guillaume Dumas and others. One of the goals of that meeting was to try out the combination of the EEG system with the Oculus Rift VR system.

For the COGITO project we are using the GTec Nautilus EEG system. Our specific system comprises of a 32-channel wireless amplifier that mounts on the back of the EEG cap, in combination with EEG caps in three different sizes. The caps have 64 holes at a subset of the  locations of the 5% electrode placement standard. We are not using the “Sahara” dry electrode option, but rather the regular wet electrodes.

We started by removing all electrodes and cups from the cap, to get a clear view on which electrode sites are accessible. The central electrode locations (i.e. the z-line), temporal electrode locations and occipital electrode locations are occluded by the VR head mount. But there are still plenty of electrode locations accessible.

We are using the Nautilus in combination with wet electrodes. These consist of a small cup that is mounted in the holes of the cap. Each cup comes with a label. It is a bit fiddly to mount all the cups on the cap; not something to do every day.

The electrodes themselves are fixed to the wireless amplifier and “click” smoothly onto the cup. We made some small adjustments to the selected electrode sites to have them all fit nicely in the spaces of the VR head mount.

The Nautilus EEG system has two sets of wires, going to the left and right. That is convenient with the head mount.

Putting on the VR headset on top of the EEG cap and removing it again requires care, it is easy for electrode wires to get stuck. But once the VR headset is mounted over the EEG cap it all fits nicely and is comfortable for the subject.

Below you can see Guillaume, wearing the EEG and VR system while he is seeing the 3D movie and while EEG is recorded.

10 thoughts on “EEG combined with VR

  1. Robert Post author

    The list price for the 32-channel system is somewhere around 15,000 euro. We bought it for the Cogito project, which G.tec generously supported by offering the system to us with a significant discount.

    Reply
  2. Rikke Petersen

    Is this research published? If it is, can you link it to me? I am doing research close related to this, for my master thesis, so I’m very interested.

    Reply
  3. Plaffordance

    Hello Sir, I want to ask you, Could I use these pictures for my lecture ppt materials?
    I’m just surfing about the Collaboration between VR and EEG system for neuroarchitecture.

    Reply
    1. Robert Post author

      Dear Plaffordance, thanks for asking. Hereby I grant you permission to use the photo’s from the blog post “EEG combined with VR” for your lecture material. Best regards, Robert

      Reply
  4. Huseyin Beykoylu

    Hi Robert! I am a PhD student at Leiden currently working on a project with a combined EEG-VR design. I was wondering if you had any tips for minimizing EM or any other artefacts in the EEG signal. We use a Biosemi ActiveTwo system in Leiden. Please let me know if you require any further info. Thanks!

    Reply
    1. Robert Post author

      Hi Huseyin,

      The frequency of the electronics in the VR headset (and potentially the digital radio) is much higher than that of the EEG, and the EEG is low-pass filtered prior to digitization to avoid aliasing. That means that electronic noise of the headset, even though large in amplitude, might be sufficiently suppressed and not visible in the EEG. Furthermore, EEG in general is noisy anyway, also if you record it without a VR headset. So the artifacts you see might be more general in nature and relate to your task, your subjects behaviour, your EEG system, or the environment, rather than to the VR.

      Hence the first thing to do is to check whether you have any electromagnetic interference and whether you have other artifacts that do relate to the VR. If not, there is no problem – or at least no problem other than you would have recording EEG anyway. If you do see interference or additional artifacts, the nature of those can give you information on how to deal with them: either take action to avoid them, or to clean the data afterwards.

      I suggest that you do an EEG recording, alternating with the VR headset switched on and off (say for a minute each, and repeat that multiple times). That allows you to look for differences in the spectrum of the continuous EEG signal. In the same way you can experimentally evaluate other artifacts, for example movement artifacts (have the participant move with the VR headset on and without the headset and check for differences in the artifacts); it might well be that the artifacts are not related to the VR headset but merely to the movement.

      Besides trying to avoid artifacts and cleaning the data, it is also important to consider the confounding effects on your analysis. Eventually you might want to do a statistical comparison; for that you should ideally design your experimental contrast such that there is no confounding effect (i.e., the artifacts – if present – are not different between conditions).

      best regards,
      Robert

      Reply

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