[Eeglablist] Help with Channel locations and ICA for 32-channel BrainVision data?

[Makoto Miyakoshi]

Dear Natalie,

Maybe you have crazy outlier in these eye channels. Show me the Component 1
ERP image, ERP, and spectra. Probably, removing the left frontal channel
would solve the problem. You seem to be ok with channel locations.

Makoto


2014-03-24 16:46 GMT-07:00 Natalie Prowse <NatalieProwse at cmail.carleton.ca>:

>    Hi,
>
>
>  We're trying to process 32-channel Brain Vision files in EEGLab, but are
> running into an issue in ICA where the component headmaps all look the
> same, so I'm not sure if it's an issue with the ICA or with the electrode
> channel file we are using.
>
> Here is an example ICA plot and the electrode .ced file.
>
> https://dl.dropboxusercontent.com/u/47453764/ICA-HEADMAPS-32CH.png
>
> https://dl.dropboxusercontent.com/u/47453764/32ch_BrainVision.ced
>
>
>   I'm open to any suggestions as to what to do.   We DON'T have Brain
> Vision Analyzer - everything was recorded with Pycorder and exported as
> .vhdr, .vmrk and .eeg files.
>
>
>  We are using EEGLAB 13_1_1b
>
>
>  Because the events were unfortunately coded with characters and numbers
> (e.g. "S  8", "S  7" ), I had to read all the data in via small program
> that calls via pop_loadbv() and then strips the string portion of the
> event, and merges using pop_mergeset  to produce a single merged .set file.
>  I cannot seem to get the events to be properly recognized if I use
> pop_biosig to read the files.
>
>
>  I read in another post that said you don't need a channel location file
> if you are bringing data in from BrainVision Analyzer, but we don't have
> the Analyzer software - we only use pycorder.  To get the .CED file I
> loaded a text .elp with just the channel numbers and names, used the "Look
> up locs" button in EEGLAB and applied the "Use BESA file for 4-shell dipfit
> spherical model". I am REALLY new to this so I'm not sure that this was the
> right thing to do at all.  Can someone please help out with either
> recommendations on how to get the correct locations for BV data that
> DOESN'T come from the Analyzer software?
>
>
>  Many thanks,
>
> -Natalie
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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