[Eeglablist] About ICA

[Makoto Miyakoshi]

Dear Leonardo,

> 1- As I understood, we need to apply the ICA data because it is clean to
the (e.g., raw data that is not clean). Is this correct? I.E., do I need to
copy data from data number 7 to raw data (number one?)

The recommendation is that you run ICA, then you perform epoch rejection ON
ICA-DECOMPOSED TIME SERIES (i.e. IC activation), then run ICA again.

> Let's say I performed ICA and now my data reached number 7 in the
preprocess stage within eeglab. Now, I'm satisfy with the results of this
data after ICA, how can I apply this note on the data Is it necessaay to
apply the results (copy it) to the dataset 1(raw data)? if yes, then I need
to do the follwing steps:

No, save the dataset instead. That's your cleaned data.

> 2- What is the next step after this important note? after copying the
data, what should we do?

Compare ERP/ERSP/ITC/etc across conditions to answer your question.

FYI, there is alternative and unofficial wiki page for the preprocessing
issue.
http://sccn.ucsd.edu/wiki/Makoto's_preprocessing_pipeline

Good luck.

Makoto

On Wed, Dec 16, 2015 at 6:49 AM, Leonardo Lion <llionname at gmail.com> wrote:

> Hi EEGLAB list,
>
> I have quesnito reslted to the impplimentation of ICA, my quesitno belong
> to the link
>
> http://sccn.ucsd.edu/wiki/Chapter_09:_Decomposing_Data_Using_ICA
>
> where there is this note:
>
> *Important note:* we believe an optimal strategy is to:
>
>    1. Run ICA
>    2. Reject bad epochs (see the functions we developed to detect
>    artifactual epochs and channels, if any, in the tutorial on artifact
>    rejection <http://sccn.ucsd.edu/wiki/Chapter_01:_Rejecting_Artifacts>).
>    In some cases, we do not hesitate to remove more than 10% of the trials,
>    even from 'relatively clean' EEG datasets. We have learned that it is often
>    better to run this first ICA composition on very short time windows.
>    3. Run ICA a second time on the 'pruned' dataset.
>    4. Apply the resulting ICA weights to the same dataset or to longer
>    epochs drawn from the same original (continuous or epoched) dataset. For
>    instance, to copy ICA weights and sphere information from dataset 1 to 2:
>    First, call menu Edit > Dataset info of dataset 2. Then enter
>    *ALLEEG(1).icaweights* in the *ICA weight array ...* edit box,
>    *ALLEEG(1).icasphere* in the *ICA sphere array ...* edit box, and
>    press *OK*.
>
>
> 1- As I understood, we need to apply the ICA data because it is clean to
> the (e.g., raw data that is not clean). Is this correct? I.E., do I need to
> copy data from data number 7 to raw data (number one?)
>
> Let's say I performed ICA and now my data reached number 7 in the
> preprocess stage within eeglab. Now, I'm satisfy with the results of this
> data after ICA, how can I apply this note on the data Is it necessaay to
> apply the results (copy it) to the dataset 1(raw data)? if yes, then I need
> to do the follwing steps:
>
> Edit > Dataset info of dataset 1. Then enter *ALLEEG(7).icaweights* in the
>  *ICA weight array ...* edit box, *ALLEEG(7).icasphere* in the *ICA
> sphere array ...* edit box, and press *OK*.
>
>
> 2- What is the next step after this important note? after copying the
> data, what should we do?
>
> Thanks.
> Leonardo
>
>
>
>
>
>
>
>
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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