- MNE version: e.g. 1.0.3
- operating system: Windows 10
Hi all,
I have been trying to preprocess some recently collected data but keep running into an issue when I try to take the ECG and EOG artifacts out with Projections or ICA (so essentially 2 different problems but only one needs to work reliably). I will give good and bad examples so the problem is clear. I have one participant that gives great projectors. Below is just the epoched ecg projector for my good participant:
However, all my other participants have at least one projector that looks bad (But not always the same one). Here is an example of one that had a bad ECG:
I am unsure why this happens, it appears different channels spread the projection out in time. I do have separate channels being recorded for ecg veog and heog. I do a projection for each one, and everyone is different for what projector is bad. I use the following code to make these:
“”“”"
ecg_evoked = mne.preprocessing.create_ecg_epochs(raw,ch_name=‘ECG’).average()
ecg_evoked.apply_baseline((None, None))
ecg_evoked.plot_joint(title=‘ECG’)
veog_evoked = mne.preprocessing.create_eog_epochs(raw, ch_name =‘VEOG’).average()
veog_evoked.apply_baseline((None, None))
veog_evoked.plot_joint(title=‘VEOG’)
heog_evoked = mne.preprocessing.create_eog_epochs(raw, ch_name =‘HEOG’).average()
heog_evoked.apply_baseline((None, None))
heog_evoked.plot_joint(title=‘HEOG’)
“”“”"
Because every other participant has at least one of these messy projectors I do not apply them. Instead I tried using ICA instead. The issue that arises there is that for my participants that gave good projectors, I get a read out of a clearly selected ICA component for the ecg, but when I actually look at the components I do not see anything that looks like ecg. You can see that ICA001 is automatically selected:
The opposite happens with my participant that gave me a bad ecg projection, where no clear ecg component is recognized but I do at least see some ecg like behavior in one of the components, however, it is never not separated out enough and using more or less components does not end up working. More components splits the ecg into more components instead of splitting non-ecg noise out of it.
Any suggestions on how to overcome this step would be greatly appreciated. Additionally, I am not sure why the ECG, VEOG, and HEOG show up in the ICA readout. It does appear I can use them, but with no ICA head models matching them, I am guessing they are just a duplicate of the originally recorded raw channels and thus not a real option to use to clean the data.
I am not sure if the messy looking projectors are options, or if this will come down to both options being not great but which is the clearest one of the two. I would use both to use the pros and cons of each method, but at the moment, most participants that have a bad projection for a particular artifact also have bad ICA components for that same artifact. When trying to apply those messy projections to the data sometimes they clear out the artifact fairly well, and sometimes they barely touch it. Either way, I am worried about using the messy projections because they could possibly take out too much good eeg data.
Please let me know if any of this is something any of you have seen before and what is that best way to overcome it.
Thank you,
Matt