[Eeglablist] ICA analysis

Isaiah Innis isainnis at indiana.edu
Tue Apr 4 07:00:01 PDT 2017

 Dr. Baloni:

1. Yes, you would interpolate after the second ICA. I personally
interpolate as the last pre-processing step. Also I assume you are
referring to "clean raw data" and not cleanline, as the latter only removes
line noise.

2. Yes, your rank would be 128 -10 = 118. If the channels were deleted from
the dataset entirely ICA should detect this and run fine without additional
options. If not then you should use the 'pca' command. Are you average
referencing your data before ICA? In that case your rank would be 117 (at
least as I understand it - someone on the list please correct me if this is
inaccurate), otherwise it would be the number of channels remaining = 118.

Remember that if you remove any components in the 1st ICA the 2nd should be
run on the original number of components minus the number removed (e.g.
117-25 = 92).

Thank you,

On Thu, Mar 30, 2017 at 6:42 AM, Dr. Sonia Baloni <sbaloni at cbcs.ac.in>

> Hi All,
>     I am new to EEGlab and trying to work with ICA analysis. I have been
> reading the eeglab list mails on ICA topic. I have gather few footnotes
>  and few question which I would like to ask:
> 1. Cleanline algorithm removes bad channels from the data. Posts in
> EEGlablist suggests that interpolation should be done after ICA.The
> tutorial suggests that two ICAs should be performed on the same data-set.
> So if we are performing two ICAs, we should interpolate these channels
> after second ICA?
> 2. I assume rank of the data (used in ICA analysis) would be equivalent to
> the number of channels in data after running clean line function. If there
> are for example 128 channels with which data was collected and 10 channels
> were removed with clean line function then the rank of the data would be
> 118. If we now want to run ICA on this data do we need to add “ ‘pca’,117 “
> in command line option - next to ‘extended’, 1 ? as suggested in  the
> tutotrial : https://sccn.ucsd.edu/wiki/Chapter_09:_Decomposing_Data_Us
> ing_ICA.
> Thanks a lot.
> Best
> Sonia
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Isaiah Innis
Indiana University '13
EEG Technician, IUB IRF
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