[Eeglablist] Baselining and filtering for ICA with epoched data

[Ahmad, Jumana]

It depends if you want to examine component activity below 1Hz. Most artifacts of interest, such as blinks and saccades should be higher frequency etc.


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Jumana Ahmad
Post-Doctoral Research Worker in Cognitive Neuroscience
EU-AIMS Longitudinal European Autism Project (LEAP) & SynaG Study
Room M1.26.Department of Forensic and Neurodevelopmental Sciences (PO 23) | Institute of Psychiatry, Psychology & Neuroscience | King’s College London | 16 De Crespigny Park | London SE5 8AF

Phone: 0207 848 5359| Email: jumana.ahmad at kcl.ac.uk<mailto:antonia.sanjose at kcl.ac.uk> | Website: www.eu-aims.eu<http://www.eu-aims.eu/> | Facebook: www.facebook.com/euaims<http://www.facebook.com/euaims>


________________________________
From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> on behalf of Eric Fields <eric.fields at bc.edu>
Sent: 21 February 2018 03:45:30
To: EEGLAB List
Subject: [Eeglablist] Baselining and filtering for ICA with epoched data

Hi,

I know there have been other threads related to this, so I apologize if this has been addressed directly and I missed it.

Groppe et al. (2009) showed that ICA gives more reliable results if you use the full epoch instead of the prestimulus period to baseline. The reason generally given for this is that baseline correction changes the scalp distribution of sources depending on what is happening in the baseline period. By this logic, using the full epoch should improve ICA (because longer periods are less affected by random variations), but no baseline correction at all should be even better.

Meanwhile, Winkler et al. (2015) have suggested that ICA works best on data high pass filtered at 1-2 Hz.

Assuming I prefer to use a 0.1 Hz high pass filter (because of distortions 1 Hz filters can cause in the ERP: Tanner et al., 2015), I have two questions:


  1.  Does the removal of additional low frequency noise you get from using a full epoch baseline (vs no baseline) outweigh the downsides of baseline correction for ICA?
  2.  Alternatively, is it appropriate to apply a 1 or 2 Hz filter to the data used for ICA training, and then apply the ICA solution to an EEGset filtered at 0.1 Hz? Winkler et al. suggest this, but what happens to the low frequency information in the data when the ICA solution that has been learned without it is applied? Can this cause problems?

Thanks!

Eric

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Eric Fields, Ph.D.
Postdoctoral Fellow
Cognitive and Affective Neuroscience Laboratory<https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww2.bc.edu%2Felizabeth-kensinger%2F&data=01%7C01%7Cjumana.ahmad%40kcl.ac.uk%7C60790510144d4d17f8f608d579548d03%7C8370cf1416f34c16b83c724071654356%7C0&sdata=Vmoa8t0Q6S95V85lnDxKRWHj4Wt%2B2Pw87O2v5nSZE%2BM%3D&reserved=0>, Boston College
Aging, Culture, and Cognition Laboratory<https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.brandeis.edu%2Fgutchess%2F&data=01%7C01%7Cjumana.ahmad%40kcl.ac.uk%7C60790510144d4d17f8f608d579548d03%7C8370cf1416f34c16b83c724071654356%7C0&sdata=KkZ5TQyb7BlOduU%2BXU66q2I5qJJXDvjk%2BPguBy3veQI%3D&reserved=0>, Brandeis University
eric.fields at bc.edu<mailto:eric.fields at bc.edu>
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