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

Teon Brooks teon.brooks at gmail.com
Sat Jun 4 21:13:09 EDT 2016
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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.

Feel free to follow up and I can try to further debug this problem.

Hope this helps,

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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