Dimensionality reduction of EEG data

Hello everyone!

I’m quite new to MNE and the more technical side of neuroscience in general, so please forgive if I’m making some obvious mistakes.
I’m working on a project for which I want to do a combined analysis of fnirs and eeg resting data to look in to neurovascular coupling. I have around 70 participants and the data is already down sampled but still too large, I will need to do a dimensionality reduction of the eeg data before doing the combined analysis with the fnirs data for each participant. My questions are:

  1. What method do you think is most suited for this task? In the end I would like to end up with a raw object reduced to a few channels (whatever they will represent will depend on the method of course) that represent as much of the original data as possible for each participant. Methods that I think might be suitable are spatio-temporal clustering and source localization, but please let me know if you have other suggestions.

  2. Do you see any problem if i use this data then after for the combination with the fnirs data and later on for group level statistics?

Thank you in advance for your help :slight_smile:

Best regards,

Lennart

-MNE version: 1.3.1

  • operating system: Ubuntu 22.04.2 LTS

Hello,
I would really appreciate some feedback! Or if I have asked a stupid / too general question could you maybe give me some feedback on how to improve my original question?
Best regards,
Lennart

Hi Lennart,

Have you looked at the MNE-NIRS package: https://mne.tools/mne-nirs/stable/auto_examples/index.html ?

I am not too familiar with fNIRS but I know that it measures blood-oxygenation similar to fMRI. It’s a different measure of neural activity than EEG which measure postsynaptic currents. You will have to dig in the literature a bit to understand what methods might be best for appropriate comparison of BOLD activity and EEG/MEG. This might be a good starting point for example: https://journals.physiology.org/doi/full/10.1152/jn.01005.2009

Mainak

Hello Mainak,
Thanks a lot for your Response! I probably didn’t make it clear, but I am using both EEG and fNIRS data. I am using the mne-nirs package you mentioned for the preprocessing of the fNIRS data. The main Problem I have right now though is that for the method I would like to use (cross frequency coupling between EEG and fNIRS) I need to somehow reduce the dimensionality of the EEG data to reduce the computational resources needed. The package I would like to use for the combined analysis is this one btw: GitHub - pactools/pactools: Phase-amplitude coupling (PAC) toolbox (it interfaces with mne). So my question is: Which method do you think would be most suitable to reduce the eeg data (eg. ICA/PCA, clustering, source estimation etc.) so when I later on do the cross frequency coupling analysis with the fnirs data I for example only have to calculate it for eg. 10 eeg channels instead of the original 32? Sorry again if my wrong utilization of the terminology is confusing, I hope I could get across where my problem lies. Thanks so much again!
Best Regards,
Lennart

I have found another work around, so please consider this topic closed.
Best regards,
Lennart

Hi
Could you find a workflow for conducting fNIRS-informed EEG source estimation?
If so, can you share some insights or related information?