[Eeglablist] BrainVision files

[Dr. Ingmar Gutberlet]

Dear Lars,

most people I know who do combined EEG/fMRI recordings AND wish to work with their data in EEGLAB actually do not use the fMRIB plugin for gradient artifact correction due to the memory limitations in Matlab you describe and which prove crippling for all but very small datasets. The problem is actually aggravated further by the fact that nonsynchronized data would also require upsampling by a factor of ~10 for offline alignment and this is when Matlab surely hits the memory ceiling.

Typically, these people would therefore perform the gradient artifact correction with BrainVision Analyzer and then export the data to EEGLAB to continue on with the OBS pulse artifact correction of the fMRIB plugin. After gradient correction the data will typically have been downsampled by a factor of 10 or 20 and the resulting file size will be digestible for Matlab/EEGLAB. Of course, being one of the people responsible for the algorithms used in BrainVision Analyzer I would also like to invite you to try your hand at its (excellent) pulse artifact correction, but I have to admit that Rami's OBS approach is a good choice as well... ;-)

Regarding your second question: The export from EEGLAB to the BrainVision file format works very well and the data does not even have to be imported or actively read into Analyzer. Simply add the files  to your workspace's Raw Files folder and they will show up ready for further action.

Best regards,
Ingmar

--
Dr. Ingmar Gutberlet
Customer Support Manager
Brain Products GmbH



From: eeglablist-bounces at sccn.ucsd.edu [mailto:eeglablist-bounces at sccn.ucsd.edu] On Behalf Of Michels Lars
Sent: Mittwoch, 28. Oktober 2009 16:35
To: eeglablist at sccn.ucsd.edu
Subject: [Eeglablist] BrainVision files

Dear EEGlab members,

I am currently performing a MR gradient correction for simultaneously recorded EEG-fMRI data in EEGlab.

In principle it works, however, it works only for files with a sampling rate well below 5000 Hz. Otherwise I get an error message: Out of memory. I thought the correction will work best for files with the (original) sampling rate of 5000 Hz. Is there any way to import the large raw file to EEGlab (file size is about 600 MB)?

Second question: There is an option to export the file to BrainVision in EEGlab. Does anybody now whether the (exported) file can be read/imported in BrainAnalyzer?

Best
Lars

Dr. phil. Lars Michels
Postdoctoral Fellow
Universitäts-Kinderspital
Steinwiesstrasse 75
8032 Zürich
Tel.  0041 44 266 78 28
Fax  0041 44 266 71 53
http://www.kispi.uzh.ch/af/ForschungLehre/zentrum_de.html






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