[FieldTrip] Question about loading in ERP data

[Amna Hyder]

Alternate possible solution!!
I thought I would add that the reason I am trying to import grand averaged
ERPs from ERPlab is because I am running into some issues with the
ft_timelockgrandaverage function when I use it on individual ERPs in
fieldtrip. If I do cfg.keepindividual = 'yes' (which is required for
cluster permutation analysis), the "avg" field is missing from the results.
I only see the avg field if I specify "no" to keepindividual. I saw that
someone had an issue with this in 2015 (
https://mailman.science.ru.nl/pipermail/fieldtrip/2015-March/021876.html). I
have tried to combine the grand average ERP by doing it once with
keepindividual='yes' and once with keepindividual='no'. See below:
    [avgERP2]          =  ft_timelockgrandaverage(cfg);
    avgERP.individual = avgERP2.individual; %avgERP has only the "avg"
field and is missing "individual". The opposite is true for avgERP2
    avgERP.dimord = avgERP2.dimord;

All of this matters because when I try to apply ft.math on this data to
compare conditions I get the following error:    'the requested parameter
is not present in the data'.
It doesnt specify which field, so I am worried that there is some error in
the way ft_timelockgrandaverage is working.
If you can help out with this issue, I wouldn't need to import already
grand averaged ERP files from ERPlab.
Thanks so much for your prompt response.
Amna

On Tue, Nov 26, 2019 at 10:37 PM Julian Keil <julian.keil at gmail.com> wrote:

> Hi Amna,
>
> is there a specific reason why you want to export the ERPs as ICA
> components?
> eegla2fieldtrip has the option to use ’timelock’ as the second input
> option, which might be more sensible in your case.
>
> Hope that helps,
>
> Julian
>
> Am 27.11.2019 um 02:23 schrieb Amna Hyder <hyder.amna at gmail.com>:
>
> Hi,
> I did all my preprocessing in EEGlab and ERPlab and wanted to put in my
> ERP files into fieldtrip to do the cluster permutation analysis on my ERPs.
> I tried using the function eeglab2fieldtrip as specified in the following
> link:
> https://mailman.science.ru.nl/pipermail/fieldtrip/2006-March/000441.html
> I used the 'component analysis' option eg: comp = eeglab2fieldtrip(ERP,
> 'componentanalysis').
> However, I get the following error:
> Reference to non-existent field 'icachansind'.
> Error in eeglab2fieldtrip (line 54)
>  header.label   = { tmpchanlocs(EEG.icachansind).labels };
>
> When I comment out these lines I run into another error:
> Reference to non-existent field 'icaact'.
>
> Error in eeglab2fieldtrip (line 119)
>         if isempty(EEG.icaact)
>
> It seems that this function requires ICA information in the EEGLAB ERP
> file, which isnt stored in the way that it is called. Can someone take a
> look into the function? Do I have to get the ERPs again in fieldtrip?
> Amna
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