connecting electrodes with the FRI 19 channel headband

Dreaming_GeekDreaming_Geek Atlanta
edited June 2015 in Electrodes
I just bought the 32 bit R&D kit with daisy chain.
The headband should be here in a couple of days.

19-Channel EEG Headband

Am having a hard time finding the docs that tell me how ALL the electrodes connect to the pins and the headset.
Please help a n00b?


  • wjcroftwjcroft Mount Shasta, CA
    edited June 2015
    Interesting I did not know FRI was selling a 19 channel version. Did you order enough (16) of the dry sensors and cables to go with it?

    Or are you asking how to use the gold cup electrodes with this headband? That is not as straightforward. As the holes in the headband are designed to fit the dry sensor combs, not regular cup / paste electrodes. Perhaps Karl @KZurn or Brooks @jbzurn will jump in here.

    With the dry sensor cables, those are plugged into the touchproof adaptors you receive with the R&D kit. You are the one who chooses how you want to map your 10-20 locations to the channels. Most BCI setups use ear lobes for the reference, and those are frequently linked with a Y cable. Your Bias lead can go anywhere on the head; the Electro-cap places it at AFz. A midline location is good as it injects the anti-noise signal equally to both sides of the head.

  • Thanks for your prompt answer.
    Obviously, I have a lot to learn.

    Other than your suggestions above, the wires can be connected to the pins in no particular order?

    Are these the proper wires to use with the touch-proof connectors?

    How many might I need? 16?  18?  20?
    And the dry electrodes?  How many comb-type for the hair area?
    How many cup-type for the forehead?
    Anything else that I need?

    Thanks in Advance
  • wjcroftwjcroft Mount Shasta, CA
    FRI sells packages with both leads and electrodes, so probably better pricing there.

    You can connect any channel to any 10-20 site, it's your choice. You can do a lot of good stuff with just 8 or less channels. See the OpenViBE speller tutorial. Note that without the daisy, you get 250 sps, but adding the daisy drops you to 125 sps, which is a consideration in some cases. Many neurofeedback protocols just use 2 or 4 channels.

    I don't know anyone doing source localization with OpenBCI yet, but in that case 16 channels would give decent coverage, still not full 19 channel. I think the mix of the comb vs. cone electrodes in the packages allows you to work with most head/hair types. Since this is very dependent on the hair coverage of the person you are working with.

    Another way to use the dry electrodes is with the g.tec g.GAMMAcap, mentioned on some other threads, use the search box. Or with the BrainNet elastic 10-20 point mesh. The material used in the FRI straps is Velcro One-Wrap, which you can buy in 12 foot rolls.

  • wjcroftwjcroft Mount Shasta, CA
    Well, sure, plenty there. Ask yourself what type of BCI you are interested in, and then look around to see how many channels you need. Chip has done amazing things only using a few channels generally,

  • Now you have me intrigued with source localization.
    I did find something on github, but that sort of package makes my ears bleed.

    I was trying for something like that recently.
    I tried making a 3D brain atlas from an old MRI in Slicer.
    But, haven't quite figured out how to get my EEG data to show over my actual brain.
    I posted details here.
    Dreaming Geek Group
  • wjcroft- You said, 'You can connect any channel to any 10-20 site, it's your choice.'  Last time I tried connecting 8 leads, they didn't correspond to the default mapping in the OpenBCI GUI.  So, clearly I have no idea what pins correspond to what positions.  All the gear to use the touchless adapters should arrive soon.  I would like to have a better idea of the proper place to connect them.  I found a good map of the sites on the head on the GA Tech site.  I just need to know where to connect them properly for all 16 channels.  Can anyone help?  image
  • wjcroftwjcroft Mount Shasta, CA
    The GATech layout there is decent, nice symmetry. Again, there are no 'standards' for how channels map to 10-20 sites. You can choose anyone you like.

    As far as lining up with the OpenBCI_GUI head map, just touch / wiggle each electrode one at a time and see what lights up. That's one correspondence you can use, but it was chosen arbitrarily.

    In most BCI software, the channel to 10-20 site mapping is handled in one of the setup dialogs. So you can map it however you like. In OpenBCI_GUI, that map change dialog is not yet present, so just one layout was chosen.

    There are EEG data stream file standards, such as EDF, BDF, XDF -- that carry a channel mapping table as part of the format. The free EDFBrowser package allows you to import from CSV files (such as our GUI creates).

  • Thanks.
    Guess I am just having a hard time getting my head around there not being a set standard.

    I wonder if BrainBay's mapping differs from the OpenBCI GUI?
  • wjcroftwjcroft Mount Shasta, CA
    In BrainBay, there is no 'mapping'. Channel routing and processing is entirely driven by your circuit wiring diagram.
  • Thanks.
    Just got the gear and am fumbling forward.
  • Is there any mapping in OpenVibe?
  • wjcroftwjcroft Mount Shasta, CA
    All mappings are arbitrary and determined by the experimenter. You can see Jeremy's channel mapping for the OpenViBE P300 speller here,

  • Thanks for the tips !
  • wjcroftwjcroft Mount Shasta, CA
    The default mapping for the 8 channels to 10-20 sites, used by the OpenBCI_GUI program, is shown here,

    There is a similar map for channels 9-16. You can figure this out yourself by touching electrodes and see what lights up on the OpenBCI_GUI head map.

  • I combined the info from a couple of docs found here and did a quickie coloring in photoshop to keep my wires right.
    This seems to match the placement in the GUI.
  • wjcroftwjcroft Mount Shasta, CA
    Dreaming_Geek, thanks!

    Is 'R' meant to refer to 'Reference'? Generally the Reference is going to one or both ear lobes. And the Bias can go to any of the unused 10-20 or 10-10 sites.

    It would be a beneficial to integrate elements of this diagram into the tutorial docs on the OpenBCI_GUI. Hoping that someone in the lab could look into this. Rodrigo @Rceballos98 has made such additions in the past.

  • Feel free to borrow my image.
    Though someone should do a better job of coloring it.

    "Is 'R' meant to refer to 'Reference'? Generally the Reference is going to one or both ear lobes. And the Bias can go to any of the unused 10-20 or 10-10 sites."

    On the UIltracortex 3, the only unused sites are the ones right down the middle of the head which have the stronger springs to keep it in place.
    Are you saying I should run BIAS to one of those, and send both ears to SRB1?
  • wjcroftwjcroft Mount Shasta, CA
    Yes, most BCI's and neurofeedback use the ears for reference and place Bias at some unused site on the head.

    The SRB closest to the board is SRB2, and it is the default reference.

  • Thanks for the contribution Dream_Geek!
    I'll look for a space to add this into the documentation. Maybe even having it in the getting started guide next to electrode placements.
  • AndreBCIAndreBCI San Diego
    In OpenBCI GUI the assignment of the channels to specific 10-20 positions is now fixed. Is there any plan to match the flexibility offered by the possible electrodes location on the Mark IV with software capability to re-assign the positions?
  • wjcroftwjcroft Mount Shasta, CA

    You can add more comments at that Issue log.

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