[Eeglablist] Extracting ASR weights and applying them later

[Andraž Matkovič]

Thanks for the explanation. If I understand correctly, the cutoff of the
high-pass filter does not have much influence on the ASR results?

Another related question: In your paper in Epilepsy Research, you found
that ICA or ASR+ICA reduces phase-amplitude coupling (PAC). Do you suggest
computing PAC on minimally preprocessed data (i.e., only high-pass filter,
cleanline, channel interpolation)? Are you aware of any other work that
investigates the effect of cleaning procedures on PAC?

Best,
Andraž

V V sre., 30. avg. 2023 ob 01:06 je oseba Makoto Miyakoshi via eeglablist <
eeglablist at sccn.ucsd.edu> napisala:

> Dear Andraz,
>
> The short answer is no.
>
> If any, if the input data's PSD is similar to the preemphasis filter i.e.
> the 8th order Yule-Walker function that was heuristically determined by
> Christian (the developer) as an inverse PSD of human EEG data (i.e. the
> flattening filter, so to say), then ASR's artifact detection (according to
> its own design) works most effectively. But this does not mean it helps the
> algorithm per se.
>
> > This is useful because the ICA solution can be improved with certain
> preprocessing steps (high pass filtering at 1-2 Hz), but these
> preprocessing steps don't necessarily have to be applied to the dataset to
> which the ICA weights are applied.
>
> I have words of warning for you. See my reply to Jan. Basically, I do not
> recommend it. Remember, ICA's sensitivity is not uniform across all the
> frequencies, but its sensitivity is (practically) proportional to the
> amplitude. See my preliminary results from here
>
> https://sccn.ucsd.edu/wiki/Makoto's_preprocessing_pipeline#Why_does_IC_rejection_increase_gamma_power.2C_or_why_is_an_IC_not_broadband-independent.3F_.28For_160.2C000_page_views.2C_05.2F10.2F2021_added.2C_06.2F27.2F2022_updated.29
>
> Would you be surprised to hear that IC rejection generally INCREASES gamma
> power? If you are surprised, read my Wiki article above. It is partly
> related to what you are asking. Importantly, the lowest end of the power
> spectrum usually has highest power, that's the point. If you are omitting
> 50 Hz and above for running ICA, practically it'll do no harm.
>
> Makoto
>
> On Tue, Aug 29, 2023 at 1:02 PM Andraž Matkovič via eeglablist <
> eeglablist at sccn.ucsd.edu> wrote:
>
> > Dear all,
> > I have a question about ASR (Artifact Subspace Reconstruction). In ICA,
> it
> > is possible to extract ICA weights and apply them to another data set.
> This
> > is useful because the ICA solution can be improved with certain
> > preprocessing steps (high pass filtering at 1-2 Hz), but these
> > preprocessing steps don't necessarily have to be applied to the dataset
> to
> > which the ICA weights are applied. For example, I can run ICA with a 1 Hz
> > high-pass filter, but apply ICA weights to data with a 0.1 Hz high-pass
> > filter. I am wondering if this is possible with ASR.
> >
> > Best regards,
> > Andraž Matkovič
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