read events

[Robert Oostenveld]

Dear Karl,

Definetrial is usually called before preprocessing, not after preprocessing. Definetrial determines the trial structure, i.e. the segments that subsequently are read with the preprocessing function. Often the interesting data segments (the trials) are much shorter than the complete continuous data, so reading only the trials saves memory.

Since you have already read in all data into memory, you should use "redefinetrial" to segment your data into the trials. That also requires the trial definition to be specified in cfg.trl. The only purpose of definetrial function is t oconstruct this cfg.trl field based on the events. 

Since you manually added the triggers after reading the data in memory, you have to emulate the behaviour of definetrial. You should look at it's help and manually construct a cfg.trl field which you can hand over to redefinetrial together with the data.

best,
Robert





On 25 Feb 2010, at 18:35, Karl Doron wrote:

> My apologies if this is redundant - I believe I sent to it the megcommunity
> list and meant to send it here, so I am reposting.
> 
> Hello,
> 
> I've recently collect MEG data and had to edit trigger values. I've read in
> my BTi data using preprocessing() and inserted triggers at appropriate times
> in sub1.trial{1}(1,:).
> 
> Now I would like to use definetrial. However, the cfg file references the
> original data, with the incorrect trigger onsets and information. What
> should I list as cfg.dataset to have my imported data read?
> 
> Thanks for any help.
> 
> karl doron
> Ph.D. Candidate
> UC, Santa Barbara
> 
> ----------------------------------
> The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.
> 

----------------------------------
The aim of this list is to facilitate the discussion between users of the FieldTrip  toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis. See also http://listserv.surfnet.nl/archives/fieldtrip.html and http://www.ru.nl/neuroimaging/fieldtrip.