View Full Version : slow drifting on EEG??

14th May 2018, 10:25
ow I am conducting P300 BCI speller paradigm, and some parameters are set as below:

bandwidth: [0.1 70] Hz,
Notch: 60 Hz
Fs: 512Hz
Channel: 32 (MK2 box, pin type electrodes) + 5 EXG(ECG, EOG, EMG)
Reference: CMS electrode to left ear mastoid, DRL electrode to right ear mastoid (flat type electrodes)
Environment: laboratory
Data collection: BCI2000 software

Some slow drifts frequently occur during recording EEG, and it makes P300 classifier failed to generate feature weight.
With the same parameters, someone did not show slow drift, and someone showed slow drift over recording. There was no severe body movement during experiment (due to ear reference, all channels contain ECG component though).
My concern is whether using ear reference is good choice for P3 ERPs. We have other CMS/DRL electrode (pin type) around parietal area.
What do you think of ear mastoid reference or head reference?
I tried searching from Covoco (https://vimeo.com/265965313) but I couldn't find anything about it ! I will be greatful if you point me in the right direction.

Any help wll be appreciated.
Thank you