[Eeglablist] Flexible preprocessing (ICA then epoching and vice versa)

[Velu Prabhakar Kumaravel]

Hi Zaeem,

1) When you say high threshold, do you mean a higher value for the ASR
parameter? In ASR, the strict cleaning occurs at a lower ASR cut-off
parameter (e.g., 3). But, from our experience on newborn EEG data
(characteristic of high noise levels with non-stereotypical artifacts), a
strict threshold of 3 removes an excessive amount of neural information.
Moreover, we have repeatedly observed (both in adults and newborns) that
ASR Rejection is better than ASR Correction. (see figure 7 in this
manuscript:
https://urldefense.com/v3/__https://www.sciencedirect.com/science/article/pii/S1878929322000123?via*3Dihub*sec0190__;JSM!!Mih3wA!BlENIhq7izRcPYGOMfbHbajl61O2WkJFK7TLjiT-9X4aJ6H9jzYpA3FptCG2kB8ZaqaXGyGZvXj1X8aCYiBhDIkOdrlsK_Ax$ 
)

2) It was not clear from your email whether or not you considered
integrating ASR and ICA for your pipeline. In this case, you could use a
relaxed ASR threshold (e.g., 20) and the residual eye-related artifacts can
be removed by ICA + ICLabel.

Hope this helps.

Best,

Velu Prabhakar Kumaravel, PhD

On Mon, 6 May 2024 at 19:02, Zaeem Hadi via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Hi,
> I was wondering if it would be reasonable to keep the preprocessing
> pipeline a bit flexible as below in different participants of the same
> dataset. Particularly the order of ICA and epoching.
>
> In some subjects, continuous data is much cleaner and could be used for
> ICA with minimal rejection/interpolation. Whereas in some subjects the
> continuous data is very noisy and I was considering epoching first (which
> takes away most of the noise) and then doing ICA on epoched data in those
> subjects. I tried ASR but it keeps picking up eye-related data (blinks, eye
> movements) even with a very high threshold which I would like to keep for
> ICA and for later removal from data, so I would prefer to avoid it.
> In each case, I am doing re-referencing and epoch baseline correction
> after ICA as recommended.
> Is there an appropriate reference for justification for using this
> approach?
> Kind Regards,
> Zaeem
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