[FieldTrip] Biosemi eventtype problem

[Ricarda Braukmann]

Hi Vitoria,

Im not sure this will help you but I still wanted to come back to the
recoding that worked for me (and sorry for being so vague on it in my first
email)

So, I recoded it in Matlab. I first find the events in the bdf datafile and
then redefine them using a small script I made myself (I am convinced there
is an easier way but this worked for me  and I had limited time and mainly
wanted to have a quick look at the data):


 event = ft_read_event(bdfdataset);
 %redfine the events:
 event = EEGSynch_FFT_trialfun_BioSemiMarkerRedefine(event);

I attached my redefine function if you want to have a look. In my case the
first of the two markers should always be 255 which the script checks, but
this might be different in your case.

Let me know if anything is unclear still.
Best,
Ricarda

On Fri, Jan 23, 2015 at 1:32 AM, Vitoria Piai <v.piai.research at gmail.com>
wrote:

> Hi Ricarda, Alex, Elmeri et al.
>
> Thanks. The files I'm trying to read are .bdf.
> Ricarda, could you please clarify "I just recoded the markers."? Did you
> edit the .bdf file with a text editor?
>
> In a previous dataset I acquired with Biosemi (in combination with
> Presentation), with eventtype 'STATUS', I get the right event values in
> the right number (that is, I send 10 times marker '1', ft_definetrial
> finds 10 times marker '1').
> With this new Biosemi dataset (programmed by someone else in E-prime,
> it's not my data):
> cfg=[];
> cfg.dataset = dataset;
> cfg.trialdef.eventtype = 'STATUS';
> cfg.trialdef.eventvalue = '?';
> ft_definetrial returns markers that were not sent, and doesn't return
> markers that were sent. (The same occurs if I read the data in EEGlab by
> the way).
> It doesn't look like there's a linear transformation between what was
> sent and what FT finds. For example, markers sent were 1:21; FT returns
> [3:23 29:31], but I'll definitely look into the suggestion that maybe
> 1:21 was sent but for some reason recorded as 3:23 and the 29:31 are
> coming from somewhere else.
>
> Thanks a lot!
> Vitoria
>
>


-- 

Ricarda Braukmann, MSc
PhD student

Radboud University Medical Centre & Baby Research Center

Donders Institute for Brain, Cognition and Behaviour,
Centre for Neuroscience & Centre for Cognition

Room B.01.22
Phone: +31 (0) 24 36 12652
Email: r.braukmann at donders.ru.nl
Website: http://www.zebra-project.nl/
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