[Eeglablist] How to interpolate channels in individual epochs

[Scott Burwell]

Hi Sebastian,

The FASTER Matlab pipeline (Nolan et al., 2010; J Neuro Meth) has a
function (adapted from EEGLAB) that will interpolate channel-epochs. At one
time I discovered an issue where the function would use bad data in the
estimation of interpolated data; back then I reported it but not sure if it
has been fixed. In any case, my working / fixed version is available here:
https://github.com/sjburwell/eeg_commander/blob/master/functions/basefunc/eeg_interp3d_spl.m
 .

An important caveat: if you are using ICA (or other BSS algorithms) in your
preprocessing pipeline, it is imperative that you consider the fact that
when the interpolated channel(s) change epoch-by-epoch, the data's rank
will also change epoch-by-epoch. If you are planning to use ICA / BSS for
blink correction or other purposes AFTER interpolation, I'd strongly
suggest against channel-epoch interpolation and instead using full channel
interpolation. The changing rank epoch to epoch can cause some pretty funky
ICA results :)

Best,
Scott

On Mon, Mar 16, 2020 at 12:28 PM John Johnson <john.johnson at gatech.edu>
wrote:

> I would think any sort of (time) selective interpolation would have the
> potential of introducing bias into your results.
> Have you looked at the component activations (Plot | Component
> activations (scroll)) to see if perhaps these artifacts are represented
> by one or two components?
> Have you used [ASR
> (clean_rawdata)](
> https://sccn.ucsd.edu/wiki/Artifact_Subspace_Reconstruction_(ASR))
> (as in [Makoto's preprocessing
> pipeline](https://sccn.ucsd.edu/wiki/Makoto's_preprocessing_pipeline))
> to reduce non-stationary artifacts?
>
> John T. Johnson
> PhD Candidate - Cognitive Motor Control Laboratory
> Lab TA NEURO 4001 Neuroscience Capstone
> School of Biological Sciences
> Georgia Institute of Technology
> john.johnson at gatech.edu
> he/him/his
>
> On 14 Mar 2020, at 9:22, Sebastian Sauppe wrote:
>
> > Dear EEGLAB list members,
> >
> > Is it possible to interpolate channels only in individual epochs or
> > for specified time intervals?
> >
> > It is often the case that after ICA etc. one has segments of the data
> > where one channel has artifacts in them. But in many cases one
> > doesn’t want to interpolate a channel for the whole data set because
> > of a few epochs and one also doesn’t want to exclude epochs because
> > of a single channel with artifacts (e.g. in high-density EEG).
> >
> > Does anyone of you know of a solution to this in EEGLAB?
> >
> > Best,
> > Sebastian
> >
> > -----------
> > Dr. Sebastian Sauppe
> > Department of Comparative Language Science, University of Zurich
> > Homepage: https://sites.google.com/site/sauppes/
> > <https://sites.google.com/site/sauppes/>
> > Twitter: @SebastianSauppe <https://twitter.com/SebastianSauppe>
> > Google Scholar Citations:
> > https://scholar.google.de/citations?user=wEtciKQAAAAJ
> > <https://scholar.google.de/citations?user=wEtciKQAAAAJ>
> > ResearchGate: http://www.researchgate.net/profile/Sebastian_Sauppe
> > <http://www.researchgate.net/profile/Sebastian_Sauppe>
> > ORCID ID: http://orcid.org/0000-0001-8670-8197
> > <http://orcid.org/0000-0001-8670-8197>
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-- 
Scott J. Burwell, PhD
NIDA T32 Postdoctoral Research Fellow
Department of Psychiatry & Behavioral Sciences
University of Minnesota, Minneapolis, MN
burwell at umn.edu
github.com/sjburwell