[FieldTrip] Problem with FT_DEFINETRIAL

[Jarmo Kontinen]

Dear Ivano,
I had some problem with email, so if I am replying to you twice, I apologize.

 I was maybe a  bit unclear maybe in my first post. My files already contain
 averaged data.
Problem is to get the right data-structure to use the existing FT-functions to
do analysis on the data.

Best,
Jarmo

Ivano Triggiani schrieb am 2012-03-26:
> Dear Jarmo,

> Filedtrip needs a definition of segments of interest. For example
> reading a trigger channel or something else to cut the EEG recording
> into trials. If I have understood what you want to do is to get an
> average of general EEG (for example resting state EEG closed eyes).
> But you have to indicate which average you want to obtain, for
> example you can tell fieldtrip to divide EEG into epochs of 3 seconds
> and then to make an average of all of them.
> What you wrote is the request of an average, but you are not
> specifing of what.
> Fof example you can write a trial function that provides a trl
> matrix, i.e.:
> 0 3 0

> 3 6 0
> 6 9 0
> 9 12 0
> 12 13 0
> ...

> where first column is the start sample in seconds (you have to
> multiply it for sample rate), the second column is the end sample and
> the third is the offset (in this case is always zero), or look at
> http://fieldtrip.fcdonders.nl/tutorial/preprocessing#use_your_own_function_for_trial_selection

> best wishes,
> Ivano



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> ________________________________
>  Da: "fieldtrip-request at donders.ru.nl"
>  <fieldtrip-request at donders.ru.nl>
> A: fieldtrip at donders.ru.nl
> Inviato: Lunedì 26 Marzo 2012 12:00
> Oggetto: fieldtrip Digest, Vol 16, Issue 33

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> Today's Topics:

>    1. Re: Problem with FT_DEFINETRIAL (Stephen Politzer-Ahles)


> ----------------------------------------------------------------------

> Message: 1
> Date: Sun, 25 Mar 2012 12:11:28 +0200
> From: Stephen Politzer-Ahles <politzerahless at gmail.com>
> To: fieldtrip at donders.ru.nl
> Subject: Re: [FieldTrip] Problem with FT_DEFINETRIAL
> Message-ID:
>    
> <CAJT2k__mFC_FxgG2ggt9hJHhNp59DEZgXFMLAQ1BNoErGFJyfg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"

> Hello Jarmo,

> I haven't tried importing Brain Vision files into FieldTrip myself,
> but
> based on the code you sent it looks like the problem may be that
> you're
> missing cfg.trialdef.eventvalue (which is used to tell FieldTrip
> which
> triggers to select), cfg.trialdef.prestim, and cfg.trialdef.poststim
> . See
> the example at
> http://fieldtrip.fcdonders.nl/tutorial/preprocessing#reading_and_preprocessing_the_interesting_trials.

> If what you are trying to do is import all trials from all triggers
> in the
> file, I think you have to define your own "trialfun" function to do
> that
> (although I haven't tried this myself so I'm not sure).
> http://fieldtrip.fcdonders.nl/reference/ft_definetrial has some more
> information.

> Best,
> Steve Politzer-Ahles
> University of Kansas


> Message: 1
> > Date: Thu, 22 Mar 2012 17:14:46 +0100 (CET)
> > From: Jarmo Kontinen <Jarmo.Kontinen at ruhr-uni-bochum.de>
> > To: <fieldtrip at donders.ru.nl>
> > Subject: [FieldTrip] Problem with FT_DEFINETRIAL
> > Message-ID:
> >        <
> > permail-201203221614466509e8c700002494-Jarmo.Kontinen at msgid.mail.ruhr-uni-bochum.de


> > Content-Type: text/plain; charset=us-ascii

> > Dear all,
> > I am trying to import EEG subject averages into Field Trip. The
> > files are
> > exported with the Brainvision Analyzer in binary form
> > :subject10_konPro2002.dat and subject10_konPro2002.vhdr.
> > I have a problem with turning the data into the Field Trip
> > data-structure.
> > I
> > am following instructions given on this forum on one similar post.
> > What I
> > have
> > tried is the following:

> > cfg=[];
> > cfg.trialdef.eventtype='average'
> > cfg.dataset='subject10_konPro2002.dat'

> >  cfg=ft_definetrial(cfg);

> > Warning: no trialfun was specified, using trialfun_general
> > > In ft_definetrial at 123
> > evaluating trialfunction 'trialfun_general'
> > reading the events from 'subject10_konPro2002.vhdr'
> > ??? Error using ==> ft_definetrial at 176
> > no trials were defined, see FT_DEFINETRIAL for help

> > I am grateful for all the help.
> > Thanks,
> > Jarmo Kontinen

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