Order in preprocessing and different filters before and after ICA

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  • MNE version: 1.7.0
  • operating system: Windows 11

Hello, I wanted to ask in this post about the relationship abouth highpass filters and ICA(fit and apply).

I know that ICA should be applied on 1 hz (or higher) high pass filtered data, as recomendded in MNE tutorials, and other papers. My question is basically**, can you fit ICA on 1 hz highpass filtered epochs** , and then apply it to raw (no filter at all, no epochs) and then highpass filter again (this time at 0.1hz or other values).

I have seen some posts about it like Filter low-pass and high-pass for EOG artifac correction with ICA but I don´t get a clear picture

Basically my pipeline is:

  • highpass/lowpass filtering (1-40) hz
  • epoching of 2 seconds
  • removal of artifacts with autoreject (of 2 second epochs)
  • ICA fit on epochs [without epoch removed by autoreject] (
  • ICA apply on RAW signal
  • 2Âş - highpass/lowpass filtering (0.5-40) hz
  • re-epoching (38 seconds now, i work with very long epochs)
  • autoreject on 38 s epochs

Thanks in advance! Please let me know if you want the code I used or any other information

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Hello, yes, this seems reasonable to me!

Best wishes,
Richard

1 Like
3

Okey thanks so much Richard!

I would like to ask, why filtering AFTER applying ICA, rather than BEFORE applying it , i don´t really understand the reasons behind that decision (although people always do it after filtering), shouldn´t it be the same?