[FieldTrip] Help with definetrial for EGI .mff file

[Julian Keil]

Hi Varghese,

have you tried reading the .mff with EEGLab?
A while ago I worked with some older EGI data and reading directly to FieldTrip didn’t work. Using EEGLab with the MFFMatlabIO extension did the trick, and then you can use eeglab2fieldtrip to move over to FieldTrip.
Here’s a link to the code I used, although I did a lot of preprocessing in EEGLab: https://urldefense.com/v3/__https://osf.io/uh5rk__;!!HJOPV4FYYWzcc1jazlU!9Yh_5cOpyEfLD2Lxtli-X9YZbZN7V7Wq4TC5vPr_4jkhBDUWiH-8EJaz356EB1tVQt72kuDBEiW8TpP1zIi7R5RY6w$  <https://urldefense.com/v3/__https://osf.io/uh5rk__;!!HJOPV4FYYWzcc1jazlU!9Yh_5cOpyEfLD2Lxtli-X9YZbZN7V7Wq4TC5vPr_4jkhBDUWiH-8EJaz356EB1tVQt72kuDBEiW8TpP1zIi7R5RY6w$ >

Good Luck,

Julian

> Am 19.04.2023 um 16:27 schrieb Varghese Mathew 1881002 via fieldtrip <fieldtrip at science.ru.nl>:
> 
> Hi
> I am doing analysis on Netstation EGI .mff file using Fieldtrip, I have tried using .mff file directly and after converting to EDF. However, I am getting error in defining trials. Mostly I get an error message   Unrecognized field name "headerfile"  . 
> I would like to know how to go about this in EDF or .mff format.
> It will also be helpful if someone can help with how to modify ft_trialfun_general for .mff file as well.
> I am pasting the code I used, below.
> cfg=[]
> cfg.dataset     = 'E:\FT\OP17.mff';
> cfg.dataformat = 'egi_mff_v3'
> cfg.headerformat = 'egi_mff_v3'
> cfg.trialdef.eventtype 			= 'stim';
> cfg.trialdef.prestim 			= 1;
> cfg.trialdef.poststim 			=1;
> cfg.trialdef.eventvalue         = {'01''02''03''04'};
> cfg.trialfun                = 'ft_trialfun_general_stimmod';
> cfg   = ft_definetrial(cfg)
> 
> 
> For modifying trialfun_general
> 
> function [trl, event] = ft_trialfun_general_stimmod(cfg)
> event = ft_read_event(cfg.dataset, 'headerformat', 'egi_mff_v3');
> % Find trigger values
> trigger = [event(strcmp('stim', {event.type})).value]';
> % Note: Replace 'STI101' with the label of the trigger channel that
> % contains the trigger values for your data
> % Define trial segments
> trl = [];
> for j = 1:length(trigger)
>     if any(trigger(j) == [01 02 03 04])
>         trlbegin = event(j).sample;
>         trlend = trlbegin + 1000; % define trial length as 1 second
>         offset = 0; % no offset
>         newtrl = [trlbegin trlend offset trigger(j)];
>         trl = [trl; newtrl];
>     end
> end
> Please help with the issue, as I am trying to pick up analysis using Fieldtrip and I do not have a coding background.
> Looking forward for a response, 
> 
> Sincerely
> -- 
> Varghese Mathew
> 
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> https://urldefense.com/v3/__https://doi.org/10.1371/journal.pcbi.1002202__;!!HJOPV4FYYWzcc1jazlU!9Yh_5cOpyEfLD2Lxtli-X9YZbZN7V7Wq4TC5vPr_4jkhBDUWiH-8EJaz356EB1tVQt72kuDBEiW8TpP1zIjXO0okaA$ 

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