[Mne_analysis] trouble reading the triggers in a .BDF file

[David Soto]

Hi Teon,

thanks for the message. True I uploaded .edf version of the original .bdf
the original pdf can be found here
https://drive.google.com/open?id=0B0PbSnFq24yMZWxoWGNFNGctQmM
I think the channel info was 'STI 014' as this appears to be the only place
where I get events id

[ 65281  65282 etc]


definitely I am missing something in how to read the triggers from biosemi

Looking at mne.io.read_raw_edf, there appears to be required an annotation
file and annotation map to interprete the stim_channel...but am not clear
what is to be done here


cheers,
david

On 5 June 2016 at 03:13, Teon Brooks <teon.brooks at gmail.com> wrote:

> Hi David,
>
> I just had a look at your edf file that you uploaded, and quick question,
> is this the correct file or is there a .BDF that you are trying to analyze?
> I had a look at the header of this file, and there isn't a stim channel
> listed ($head Anna\ Priming-edf.edf). Here, I see that there are 132 EEG
> channels, and two reference channels. Is this the same file your colleague
> looked at, if so, what channel did they see the corresponding trigger
> channels on?
>
> Quick explanation for what you saw on the supposed trigger channel: the
> reader assumes the last channel of the data block is the stimulus channel
> (i.e. stim_channel=-1), which is the typical setting. The values you saw
> were the software attempt to decode the stim channel values.
>
> You can look to see how the test data for edf and bdf list either triggers
> or annotation for the triggering information (cf.
> mne-python/mne/io/edf/tests/data/).
>
> Feel free to follow up and I can try to further debug this problem.
>
> Hope this helps,
>
>
> teon
> --
> Teon Brooks <http://teonbrooks.github.io>, PhD Candidate
> twitter: @teon_io <http://www.twitter.com/teon_io>
>
> On Sat, Jun 4, 2016 at 5:07 PM, David Soto <d.soto.b at gmail.com> wrote:
>
>> Hi,
>>
>> I have data from  a study in which  Eprime was used  to send triggers
>> (integer numbers from 0-32) to the eeg system.
>> When I load the data using 'mne.io.read_raw_edf' and I try to load the
>> the trigger info  'mne.find_events(mydata)' I see only 5 digit numbers
>>  such as 65303, and even when I count the number of triggers of each type
>> it does not match what is expected.
>> I also tried to convert these numbers to 2 high and low byte numbers but
>> again the actual numbers and the amount do not match what is expected. I
>> have no idea what the problem is but I am sure the trigger info is well
>> contained in the  .bdf file, as a colleague of mine analysed this data for
>> a different research  purpose using Brain Vision Analyser. I am quite keen
>> on learning mne-python so any advise on how to load this trigger info would
>> be much appreciated.
>> In case it is useful a sample of the data can be downloaded here
>> https://drive.google.com/open?id=0B0PbSnFq24yMc2tKU29zWHZKRU0
>>
>> thanks!
>>
>> david
>>
>>
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