<p style="font-family: arial,helvetica,sans-serif;">Hi everyone,</p><p style="font-family: arial,helvetica,sans-serif;">Sorry, this is a rather basic yet lengthy question, but I've been working on my own for some time and am totally stumped. If there exists a more appropriate way to get an answer to this question than to email the entire list, please let me know; otherwise, please forgive my inexperience!
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</p>I'm trying to use FieldTrip to analyze EEG data recorded using BioPac's "AcqKnowledge" data acquisition program (data files are saved with extension .acq). This is not a FieldTrip-compatible format, but using the FT FAQ (
<a href="http://www2.ru.nl/fcdonders/fieldtrip/doku.php?id=fieldtrip:dataformat" target="_blank">http://www2.ru.nl/fcdonders/fieldtrip/doku.php?id=fieldtrip:dataformat</a>) I found the following information for importing my dataformat.
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<font size="1">"Alternatively, if you already are able to read the data into Matlab,
you can reformat that data within Matlab into a datastructure that is
compatible with FieldTrip. Raw data that is comparable with the output
of preprocessing should consist of a structure with the fields </font></p>
<pre style="font-family: arial,helvetica,sans-serif;"><font size="1">data.label % cell-array containing strings, Nchan X 1<br>data.fsample % sampling frequency in Hz, single number<br>data.trial % cell-array containing a data matrix for each trial (1 X Ntrial), each data matrix is Nchan X Nsamples
<br>data.time % cell-array containing a time axis for each trial (1 X Ntrial), each time axis is a 1 X Nsamples vector"</font><br></pre>I'm able to save my data file as a single MATLAB matrix of dimensions NSamples x NChannels (20073x10). Using my knowledge of the timestamps of events within the data file, I divided it up into two trials. Each trial is 4001 samples long, and there are six channels that I want to analyze, so I've pasted that data into smaller matrices (Trial1 and Trial2) each with dimensions 6 x 4001. Having done this, I input the following:
<br><br><font size="1">data.label = {'EEG_CZ' 'EEG_C3' 'EEG_F3' 'EEG_FZ' 'EEG_F4' 'EEG_C4'}<br>data.fsample = 1000<br>data.trial = {Trial1 Trial2}<br>data.time = {1:4001 1:4001}
</font><br><br>Here's the output those commands generate:<br><br><font size="1">data = <br><br> label: {'EEG_CZ' 'EEG_C3' 'EEG_F3' 'EEG_FZ' 'EEG_F4' 'EEG_C4'}
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fsample: 1000<br> trial: {[6x4001 double] [6x4001 double]}<br> time: {[1x4001 double] [1x4001 double]}<br><font size="2"><br>It would seem to me that I have created the datastructure defined on the FAQ site. However, the structure doesn't appear to be usable for anything (my guess is that a cfg structure is also necessary, but I haven't found how to create one that is functionally identical to the output of preprocessing, define_trials, any of the read_xxx programs from fileio)...I don't know where to begin! I'd very much appreciate any help I could get. Thanks, very happy holidays.
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<div><br>Best,<br></div><div>Kenton Hokanson</div>
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<p>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.</p>
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