[Eeglablist] ICA on epochs

[arno delorme]

Dear Andre,

yes, you should remove baseline, but you should be careful that the  
baseline length is long enough. According to an unpublished study by  
David Groppe, if the baseline is too short (~100 ms) ICA component  
reliability degrades critically. This is because you are introducing  
non-linearity by removing the baseline (if there are common generators  
that could be isolated by ICA and project linearly to each channel,  
you are making it harder for ICA by subtracting a constant from each  
channel activity - since this common source cannot project linearly to  
all channel any more).

I would personally recommend a baseline period of 1 second.
Hope this helps,

Arno

On 7 juil. 08, at 16:32, Andre Cravo wrote:

> Hello,
>
> I would like to run ICA in epochs instead of the whole dataset. To  
> do so, should I remove the baseline of the epochs before running the  
> ICA?
>
> Thanks in advance,
>
> Andre
>
> -- 
> Andre M. Cravo
> Ph.D. Student
> Roberto Vieira Laboratory of Sensory Physiology
> University of São Paulo
> www.fisio.icb.usp.br/~vinicius  
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