[Mne_analysis] Getting an evoked file in matlab

[Andres Felipe Salazar Gomez]

Hi MNE users,

I want to create my own evoked file using not an eeg average but a chunk
of it. I want to do this to analyze the localization of a signal that
appears at a specific time in the eeg (not related to stimuli). Therefore,
I will take a window of eeg containing this signal.

To use MNE and find the sources in the cortex, I need this "averaged" file
but I am having problems to get it.

I want to take a piece (200 ms) of raw data. I loaded the raw file in
matlab running the fiff_setup_read_raw and cut the chunk of interest using
fiff_read_raw_segment. I got a (samples x channel) file but I had problems
saving it as an averaged or evoked file. I tried using the
fiff_write_evoked command but I do not have the data.info piece nor the
tree structure.

With the raw data I got a regular averaged of some triggers and after
loading this file in matlab I replaced the data.evoked.evoked file by my
chunk of data and changed the data.info.filename for the new filename.
Doing this I was able to create the data structure of my "averaged" file
with data.info and data.evoked. When I run fiff_write_evoked it
successfully creates a file.  Nevertheless, it seems this file will not be
useful since I can not load it as an evoked file in mne_browse_raw. It
prompts (Incorrect number of samples in data matrix).

I really appreciate any help!!

Thank you!

-- 
Andres F. Salazar
Research Technologist
Neuroscience Statistics Research Laboratory
asalazar at nmr.mgh.harvard.edu
149 13th Street, Room 4005
Charlestown, MA  02129