[Eeglablist] CSD

Fri Jul 10 10:14:07 PDT 2020

Hello Lina,

I have tried implementing CSD on my pre-processed data for the first time
last week. I tried to follow the tutorial on their website; below is the
code which I used and it worked for me:

        %CSD

        ConvertLocations('locs.ced', 'locs.csd'); %convert EEGlab location
file from .ced or .locs to .csd

        E = textread('E60.asc','%s'); % E60.asc is a file that simply has
the list of your channels labels

        M=ExtractMontage('locs.csd',E);

        [G,H] = GetGH(M);

        data = single(repmat(NaN,size(EEG.data))); % use single data
precision

        for ne = 1:length(EEG.epoch)               % loop through all epochs

            myEEG = single(EEG.data(:,:,ne));      % reduce data precision
to reduce memory demand

            MyResults = CSD(myEEG,G,H, 1.0e-5, 10);            % compute
CSD for <channels-by-samples> 2-D epoch

            data(:,:,ne) = MyResults;              % assign data output

        end

        looping_CSD_final = double(data);          % final CSD data

        EEG.data=looping_CSD_final;

        data(:,:,:) = NaN;                         % re-initialize data
output

Basically, the CSD tool box cannot naturally apply CSD on EEG.data as it
works on 2D data. That's why we loop over epochs. You can find the
explanation. You can follow the tutorial in this link for more info:
https://urldefense.com/v3/__https://psychophysiology.cpmc.columbia.edu/software/csdtoolbox/tutorial.html__;!!Mih3wA!Qps44R7uPgkWZaWHcaKMDdomiWvceUuKAeA0Zj3EN6B7NT5shI2ynCQQO68lgJVa_9LbUg$ 
.

If anyone in the list has any comment on the above let us know please!

Best,

Haneen

On Fri, Jul 10, 2020 at 11:58 AM Lina Ismail <linaelsherif at knights.ucf.edu>
wrote:

> Thank you Arno
> I am asking for some help to implement on the cleaned epoch before the
> connectivity analysis.
> As a beginner videos for EEGLAB have significantly helped to clean the
> data but what after I failed to apply without any guidance.
> So asking for anyone who has applied it before?
>
> Get Outlook for iOS<
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> >
> ________________________________
> From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> on behalf of Delorme,
> Arnaud <adelorme at ucsd.edu>
> Sent: Thursday, July 9, 2020 8:26:03 PM
> Cc: eeglablist at sccn.ucsd.edu <eeglablist at sccn.ucsd.edu>
> Subject: Re: [Eeglablist] CSD
>
> Dear Lina,
>
> Applying current source density method is better than working with raw
> channel potentials - because if there is a superficial patch of cortex
> active, CSD will allow to extract it and mostly cancel the effect volume
> conduction. It can thus be considered as a rudimentary source extraction
> methods.
>
> It does not fully replace proper source localization analysis though,
> which should be done prior to using connectivity analysis methods.
> Connectivity analysis methods run at the channel level (raw potential) may
> return a variety of spurious connection which are uninterpretable (by
> spurious I mean that a channel being casually related to another might not
> mean that the patch of cortex underneath both channel are casually related).
>
> Arno
>
> > On Jul 8, 2020, at 6:11 PM, Lina Ismail <linaelsherif at Knights.ucf.edu>
> wrote:
> >
> > Hello all,
> > Have any one worked with current source density after cleaning the EEG
> data and extracting the epochs.
> > I am a beginner and need some help for reducing the EEG volume
> conduction before applying some connectivity analysis
> >
> > Best regards
> > Lina ismail
> >
> > Get Outlook for iOS<
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