AUXL, AUXR for Muse S (2) for EEG and EMG.

[mtp]

Hi,

I recently got the current muse S, and hacked a 5 wire micro USB (blue/gree) cable to include EMG electrodes. They work surprisingly well and I can definitely see the muscles flex and relax. (Although I question the reference point being in the forehead.)

Although it is reasonable to stream OSC, or record and post process, is it possible to get the delta within Mind Monitor between AUXL and AUXR?

I'm also getting some dry 'spider' EEG electrodes and am eager to see what they feed in. My assumption is that this would be similar to the mindlyft attachment, but would give two additional locations - maybe EEG C3/C4, or F1/F2. Would it be feasible to integrate these values into the left/right split and front/mid/back split?

I suspect that the headset might already so some of the split averaging.

[James]

You can enable "Show Aux Input" in RAW EEG Settings to display the Aux in the RAW EEG view.
There is no processing on the Aux input, it will only display raw data. These are just electrodes and don't necessarily have to be used for EEG. If you want you can hook them up to a button, or anything really.

[mtp]

I sense a resistance to adding an AUX average, or even a mapping of AUXL and AUX9 to electrode points. That would at least allow inclusion of odd/even into Left/Right and Front/Back/Central.

My understanding is that in the CSV output, there is band power for and raw, averaged on the second (based on the setting). Is it reasonable to assume that the band power is computed on device?

When I inspected the OSC output, it looks like the /muse/eeg address has 6 elements (which I assume means AUXL and AUXR raw is included.

[James]

Aux electrodes can be placed at any point on the body, or may not even be used as EEG, so it doesn't make sense to mark them at a specific location. In fact they're only AUXL and AUXR because on the original 2014 Muse 1 they each had their own USB port on the left and right of the device.

There are no band powers computed for AUX, just RAW EEG.

[mtp]

I understand. I'm suggesting that there can be a configuration in Mind Monitor that allows you to promote the aux electrode to be considered a new EEG electrodes location (ie: AUXL = C3, AUXR = C4. (Or whatever location the user wants).

The checkbox includes the values in the raw output and the raw value page.

It's unclear if the headset itself does the band power calculation or the Mind Monitor. If Mind Monitor does the calculations, then it should be able to apply consistent rules if the electrodes are mapped by the user to other locations.

I'm likely going to play with muse-js, and see if I can get the data out anyway.

I received the dry electrodes today, and it looks like they work as expected (albeit I need to find a way to have them touching my scalp more consistently).

[James]

Band powers are calculated by the closed source Interaxon SDK code and are not included for AUX electrodes.

[mtp]

Ah okay thanks. That is what I was suspecting. So I'd need to do it client side.