Share Cyton between two mice EEGs (4 channels each)

tom_foutztom_foutz St. Louis, MO
edited August 2020 in Cyton

I am using the cyton device in recording mouse EEG and it is working great. However, I was wondering if it would be possible to record two animals (4 channels each) using a single cyton. We do something similar using old EEG equipment by sharing the ground pin between animals, and I think I can do this with cyton by y-splitting the BIAS to both ground pins. However, I'm confused by the SRB1/SRB2 pins. Should I just connect one animal's reference to SRB2? Should I y-connect both animal reference pins to SRB2? Or should I connect one animal's reference to SRB1 and the other to SRB2? If the last is best, how should I configure pins? Thanks!

Comments

  • wjcroftwjcroft Mount Shasta, CA
    edited August 2020

    Tom, hi.

    Yes you can do this just as with your previous EEG equipment. Use the Y-splitter on the Bias (Ground).

    For the reference you have a couple choices. You might first try another Y-splitter on the SRB2 pin. (Not SRB1.) But this has the potential to create some cross-talk / interference between the two mice. Unless their bodies and cages are electrically isolated from each other. Might work ok, try it.

    The other idea is to use the ability of Cyton, to use the top and bottom pins of each channel, as differential plus / minus inputs. Example here, an old post where Chip setup a multi-player "shark-attack".

    http://eeghacker.blogspot.com/2015/03/brain-controlled-shark-attack.html

    If you go this route, then the 1st mouse could just use SRB2 as normal and the first four IN1N to IN4N pins (closest to board).

    The second mouse would then use the GUI control panel to 'disconnect' SRB2 as common reference for pins IN5N to IN8N. Instead setup a 4 to 1 splitter cable that connects IN5P to IN8P (farthest from board or 'top' pins) as common reference for 2nd mouse.

    The SRB2 (when enabled, the default), gangs together the INxP pins as the other differential pole from the wired INxN pins.

    Regards, William

  • tom_foutztom_foutz St. Louis, MO

    Excellent! That's exactly the sort of thing I was hoping for. I will give it a try!

  • wjcroftwjcroft Mount Shasta, CA

    But this has the potential to create some cross-talk / interference between the two mice. Unless their bodies and cages are electrically isolated from each other. Might work ok, try it.

    Hmm, on second thought, the Y-cable connecting Bias to both mice, automatically de-isolates them.

    I guess my suggestion would just be to experiment and see what wiring gets you the best signal quality. It's possible you don't need to have both mice wired to the Bias (Ground) lead, just the first.

    In 'normal' human EEG, the Ground lead has two functions: 'centers' the differential amplifier between plus and minus leads. And secondly it provides a reverse path for a small microcurrent injection to counter mains noise.

  • wjcroftwjcroft Mount Shasta, CA

    The channel input pins (and SRB2) are all "high impedance" inputs (1 megohm). So the most isolation between the two mice would be the 2nd scenario: 1st mouse using IN1N to IN4N and SRB2 and Bias. 2nd mouse uses the 4 to 1 splitter on IN5P to IN8P as reference and IN5N to IN8N as scalp leads; channels 5 to 8 disconnected from SRB2; no Bias lead on Mouse #2.

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