[Eeglablist] Artefact correction & ICA for multiple blocks during rest

Scott Makeig smakeig at gmail.com
Thu Nov 4 11:09:28 PDT 2021

Pia -

Yes, you can run an ICA decomposition across all the data (from the same
session / montage).  But the types of artifact (non-brain) as well as
brain(!) sources the decomposition identifies could indeed change in
different task conditions (e.g., EO|EC).  The multi-model option of AMICA
does a good job of finding changes in source structure. I suggest you look
at our recent publication on this:

Hsu, S.H., Pion-Tonachini, L., Palmer, J., Miyakoshi, M., Makeig, S. and
Jung, T.P., 2018. Modeling brain dynamic state changes with adaptive
mixture independent component analysis. *NeuroImage*, *183*, pp.47-61.

To remove artifacts from the data using multi-model AMICA, you will have to
remove non-brain ICs from each model only from the portion of the data that
model is trained on, and there are trade-offs we haven't explored (e.g.,
what smoothing length to use for computing model likelihoods - best to
experiment on your data with this a bit).

Scott Makeig

On Thu, Nov 4, 2021 at 1:53 PM Pia Ludwig via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Dear eeglab community!
> I am currently preparing the artefact correction for our experiment, wich
> includes several resting state eeg recordings. Now I wonder if I can I
> concatenate my data across Conditions and Blocks for running an ICA (only
> to do artefact correction)?
> The experiment is quite long and we repeat the resting three times
> (beginning, middle, end), so we have three blocks that are temporally
> spaced.
> In each block we also alternate 'eyes open' and 'eyes closed' (each 60s,
> each 4times). So in each block we have 4 trials of two conditions.
> As we are interested in how things might change across time (or if there
> are differences between eyes open/eyes closed), I thought it would be best
> to run the ICA across all relevant parts of the recording in order to keep
> artefact correction constant.
> However, since the recording is very long, and because eyes open/closed
> conditions are probably different, stationarity is probably not given.
> I found different opions on this, but do you think I can concatenate my
> data across Conditions and Blocks for running an ICA (only to do artefact
> correction)?
> Thank you soo much,
> Pia
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Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0559, http://sccn.ucsd.edu/~scott

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