[Eeglablist] continuous data

Arnaud Delorme arno at salk.edu
Wed Apr 6 18:23:08 PDT 2005


Philip Michael Zeman wrote:

>You can do ICA on the unsegmented data. One of the functions called by
>pop_runica concatenates all 'trials' or 'segmented epochs' before doing ICA.
>You should get the same components whether you are concatentating previously
>segmented data or you are running it on continuous data.
>
>Viewing the ICA sources (EEG.icaact) is a difference story.  If your data is
>really noisy it will be harder to see anything in the continuous data than
>if you segment your data and then ensemble average it.  (This can be done
>after running ICA on the continuous data if you wish.)
>
At this point of our research and comparing between ICA applied to 
concatenated data epochs or applied to the continuous data, it seems 
that running ICA on the raw data returns cleaner (and more dipolar) ICA 
components (this is an observation made by my colleague Julie Onton who 
compared the two). You should high pass the raw data above 0.5 Hz before 
running ICA though.

Arno




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