[Mne_analysis] Conflict of preprocessing recommendations: ICA and high-pass

Alexandre Gramfort alexandre.gramfort at inria.fr
Mon Mar 12 16:08:01 EDT 2018
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hi Stefan,

I don't see any caveat with this approach. High pass filtering can allow
to better estimate the mixing matrix of ICA, then you can apply to broad
band
data if you like.

Best,
Alex

On Mon, Mar 12, 2018 at 10:59 AM, Stefan Appelhoff <
stefan.appelhoff at mailbox.org> wrote:

> Dear MNE users,
>
> I have a problem, that I would like to briefly state in three parts:
>
>
> *Situation:*
>
> - I am currently working on EEG data (64 channels, 500Hz sampling
> frequency).
>
> - I want to clean the data for blink and horizontal eye movement artifacts.
>
> - For this purpose, I would like to use ICA first for a single subject, to
> identify "templates", and then apply these templates to all subjects using
> the "corrmap" approach.
>
>
> *Problem:*
>
> The conflict I encounter is when it comes to preprocessing my data:
>
> - For ICA, a high-pass filter of 1Hz is recommended (see here
> <https://martinos.org/mne/stable/generated/mne.preprocessing.ICA.html>)
>
> - For EEG data in general, high-pass filters with a cutoff > 0.1Hz have
> been shown to be problematic (see here
> <https://martinos.org/mne/dev/auto_tutorials/plot_background_filtering.html#tut-filtering-hp-problems>
> )
>
>
> *Question:*
>
> Let's assume the following:
>
> - Given my raw data, I create two pre-processed versions: One version
> high-pass (hp) filtered at 1Hz and the other version hp filtered at 0.1Hz
>
> - I calculate the ICA on the 1Hz hp data to obtain mixing and unmixing
> matrices.
>
> - *What are the caveats to be considered when I then apply the mixing and
> unmixing matrices obtained from the 1Hz hp data to the 0.1Hz hp data? *
>
>
> Help, and especially pointers to literature or examples are appreciated.
>
> I am also open to alternative approaches to addressing my situation.
>
>
> Best regards,
>
> Stefan
>
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