[Eeglablist] ICA error

Tarik S Bel-Bahar tarikbelbahar at gmail.com
Tue Dec 26 14:36:34 PST 2017

Hello Erika, here are some brief notes below. Best wishes.

******************begin notes for Erika

This is an unusual error that does not occur regularly especially if the
files meet eeglab's requirements.

The most likely reasons for this is are as follows (based on the error
message you are getting)
1. individual datasets are not the same number of channels
2. average re-referencing scheme was not run exactly the same way for each
individual dataset before concatenation
3. some issue with selecting 63 channels instead of 64 (assuming there are
64 channels in the concatenated data sets)

Here are some extra notes to follow up on that should help you sort out the

Check whether you get the error when you "select" 64 rather than 63

If you are selecting 63 channels for a specific reason, consider providing
more details for more suggestions. Note that things usually work better (to
reduce rank if you have average-referenced the data)  if you do not "reduce
via the PCA flag" but rather drop a channel after rereferencing.

If you haven't had a chance to yet, use the eeglab tutorial files and
attempt to concatenate and run ICA in the same way. Confirm that you do or
don't get the same error.

It is unusual to have 64 full clean channels, and this makes me thing that
perhaps you have replaced bad channels. See the eeglab tutorial, makoto's
pipeline, and past eeglablist posts for recommendations against
interpolating channels before ICA. Overall, you should probably be dropping
the same channels for each single-subject's single-session data.

Double-check to make sure that the single-subject datasets you are
concatenating are from the same single-subject and that they have been
cleaned/processed in the same manner.

Please follow up with the list when/if you get to a solution, as this will
help other eeglab users benefit from your experiences.

******************end notes for Erika

On Wed, Dec 20, 2017 at 8:28 AM, Erika Nyhus <enyhus at bowdoin.edu> wrote:

> I am getting the following error when I run ICA on a concatenated datasets
> and selecting 63 of 64 channels.   When I run ICA on any of the datasets
> individually I do not get an error.  I was wondering if anyone has run in
> to this problem and how they were able to solve it.
> eeg_checkset error: number of elements in 'icachansind' (64)
> does not match the number of columns in the sphere array (63)
> --
> Erika Nyhus, Ph.D.
> Department of Psychology and Program in Neuroscience
> 6900 College Station
> Bowdoin College
> Brunswick, ME 04011
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