neuromag vectorview 306 triggers

[MARUYAMA Masaki INSERM]

Dear David,


I don't remember if signals of STI001-008 are binary (0 or 1) or analogue in voltage unit. And I couldn't understand why you read 'STI014'. However, I would like to recommend you to read trigger signal of STI101 and not STI001-008. The STI101 signal ranges between 0 and 256, which is a combined signal across binary data of STI001-008. 

I attached a part of my script in "trialfun.m". If you implement in your trialfun and declare the trigger channel as STI101, I think you will find your trigger values of 5, 6, ..., 32 in the variable "trig". Please note that the trigger signals sometimes take few time slices to change its value. For example, when your stimulus PC changed trigger value from 0 to 32, recorded trigger value might increase like 0->16->32 and not 0->32. So, you may need to add your own commands to fix this issue according to your recording condition.


With best regards,
Masaki Maruyama 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% read the header and event information
hdr = read_header(cfg.dataset); 

% read trigger signal
B = read_data(cfg.dataset, 'chanindx',... strmatch(cfg.trialdef.channel,hdr.label,'exact')); 

%get rid of the offsets that are an integer number of 8192
trig=mod(B,8192);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


>-----Message d'origine-----
>De : FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] De la part
>de David Ziegler
>Envoyé : mercredi 7 avril 2010 20:53
>À : FIELDTRIP at NIC.SURFNET.NL
>Objet : [FIELDTRIP] neuromag vectorview 306 triggers
>
>Hi Fieldtrippers,
>
>I am trying to use FT to analyze data collected form a Neuromag Vectorview
>306
>and am trying to figure out the proper way to read all of my triggers.  The
>wiki noted that the old function read_trigger treated trigger values below
>5 as
>noise.  I tried using ft_definetrial, and it appears to ignore these values
>as
>well. This is the output I get when searching for readable triggers:
>
>>Reading 22200 ... 269399  =     36.962 ...   448.539 secs... [done]
>>the following events were found in the datafile
>>event type: 'STI 001' with event values: 5
>>event type: 'STI 002' with event values: 5
>>event type: 'STI 003' with event values: 5
>>event type: 'STI 004' with event values: 5
>>event type: 'STI 005' with event values: 5
>>event type: 'STI 006' with event values: 5
>>event type: 'STI 014' with event values: 5   6   7   8   9  10  11  16  32
>>no trials have been defined yet, see DEFINETRIAL for further help
>>found 882 events
>>created 0 trials
>
>My design uses all trigger values from 1-11 and 16 and 32, so I am hoping
>there
>is a way to read trigger values 1-4 somehow.
>
>Thanks!
>David
>
>----------------------------------
>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.