[Eeglablist] ICA Problem

[Makoto Miyakoshi]

Dear Habib,

Without any experience with FASTICA toolbox, let me say:
1. you should not reduce your data dimension (unless your data length is
super short).
2. sounds like FASTICA output is not sorted by variance, nor is the
polarity taken care of (but this is the original nature of ICA and nothing
is wrong with it).

Why don't you try EEGLAB's ICA. You can run it from GUI. It takes care of
sorting after decomposition, and also polarity reversal. It also detects
sub-Gaussian components such as 50/60 Hz line artifact.

Makoto

2012/12/6 Habib Paracha <ra_lums at hotmail.co.uk>

> Hi,
>
> I am performing fast ICA on a 14 Channel EEG data. Reducing the dimension
> of data from 14 to 5 components. When I perform the ICA I get a different
> result every time I run it. I am using the FASTICA toolbox available for
> matlab.
>
> The Question is how will I be able to figure out which is the most
> suitable component of all the extracted ICs. I am trying to extract the
> P300 response from the data. I get the P300 data component randomly in the
> 1st, 2nd, 3rd or 4th Component. I have to visually figure out which is the
> best extracted IC and then rest of the code.
> Sometimes I even get the P300 signal but it is inverted(instead of the
> positive peak ICA outputs a negative peak data).
>
> Someone kindy tell me a technique to automatically detect the best
> component and run the rest of the code using this component.
> Also a way to cater the wrong results of ICA.
>
>
> Regards,
>
> Habib Paracha
>
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu
>



-- 
Makoto Miyakoshi
JSPS Postdoctral Fellow for Research Abroad
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20121210/ebeb2d20/attachment.html>