[Mne_analysis] adding triggers post-acquisition

Matti Hamalainen msh at nmr.mgh.harvard.edu
Mon Jun 30 07:55:36 EDT 2008
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On Jun 30, 2008, at 5:57 AM, Mark Williams wrote:

> Hi,
> We are trying to read in text files that specify sub-conditions for  
> each of 3 separate triggers. We tried to use the mne_add_triggers  
> to do this, but encountered the following error message after it  
> read in the text file correctly:
> 'Cannot process floats yet.'
> We couldn't work out what floats are, or why they couldn't be  
> processed in this case...

This refers to the type of raw data. mne_add_triggers is an old  
utility which only handles 16-bit integers not floating point numbers.

> To give a concrete example of what we're trying to do, we have a  
> single trigger in the MEG data indicating 'condition 1' and we want  
> to divide these trials into 'condition 1 location 1', 'condition 1  
> location 2', 'condition 1 location 3', and 'condition 1 location  
> 4'. We have which trials fall in these sub-conditions in a text file.
> We also tried using Load event data to load a re-written .eve file  
> with the additional triggers changed manually but this didn't seem  
> to do anything.

The event file works. However, there is no apparent change in the  
display when you load an event file to mne_browse_raw; the program  
just replaces the trigger line in the data with the information in  
the file when it looks for triggers. If you use an ave file, you need  
to specify the event file with the 'eventfile' option in the file.

- Matti


Matti Hamalainen, Ph.D.
Director, Magnetoencephalography Core
Athinoula A. Martinos Center for Biomedical Imaging
Massachusetts General Hospital
Building 149, 13th Street, Mailcode 149-2301
Charlestown, MA 02129-2060

e-mail          msh at nmr.mgh.harvard.edu
Tel             +1 617 726 0323
FAX             +1 617 726 7422

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