Dear all, I executed oscillatory TES with trapezoidal shape during EEG recording. Although I have some stimulation free intervals that I can analyse the signals, it would be good to see what's going on during the stimulation too. Does anyone has an idea of how to do it? I know it's mathematically possible but I'm also aware that it's kinda impossible to completely remove the artifact in EEG. I'm hoping there're by chance some people could help me out so that we can get a glimpse on the stimulation effect.
Thanks in advance.
Ping
Dear Ping,
see if the link helps you:
http://www.uwyo.edu/wheelernmr/nmr/window_functions.pdf
Dear Ping,
removing technical artefacts is mostly possible and it is easier than removing biological ones. Straightforward situation is when the tES artefact and EEG have different frequency content and you may use a filtration. Let say your tACS have frequency 30 Hz, then you can use low pass filter with cut off 20 Hz.
If the tES and EEG have the same frequency content, e.g. your tES is 10 Hz, you can try to remove the tES artefact using its time course - a priory information. This approach is trickier and it needs a bit of experimenting like recording a phantom EEG with tES in your setup to determine an image of artefacts. Such image can be selectively (in time of the tES) and adaptively (adjusted to a particular subject – will be dependent on electrodes impedances) subtracted from your signal.
Kindly, Jan
Dear Ping,
I would reccomend having a look at ICA based methods.
best
Pat
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