Clear and concise information on Electrode Montage

In eeg and neurofeedback terms the + electrode is also called the
"active" electrode. This active electrode is connected to the place
you want to measure. The other - electrode serves as a reference
electrode. Most of the time this one is connected to a "neutral" place
like the mastoid bone behind the ear, or an earlobe.
If you choose to place the - electrode to a neutral place, then you've
got what is called a "mono polar" montage. The signal you'll obtain
will be absolute since the site on the scalp will be some micro volts
against the theoretical 0 micro volts from the neutral site.
If your place the - electrode also on the scalp, you've then got a
"bipolar" montage. You're values will then be "incremental" since
you're know including another site with electrical activity going on.
If you google on these montages you'll often notice they include a
"ground" electrode which is often attached to another neutral place,
like the other earlobe. With the modulareeg, we don't have such a
"ground" electrode. We do have the DRL which is an entirely different
thing, but can also be attached to an earlobe. I normally choose the
right wrist though. Or just hold it in your hand, between two fingers.
I have a small metal disc which I can hold or attach to a wristband.
So all in all for one channel a possible (monopolar) setup could be: +
electrode to the site O1 or O2, - electrode to neutral place like an
earlobe, DRL to the other earlobe or places mentioned above. In case
of two channel setup do the same with the other electrodes and then
just hold the DRL or something like that. There also an option to
share the same - electrode for both channels. Make a Y splitting cable
so one - electrode can go into your two - sockets on your modeeg
device.