Question
Asked 2 November 2015

Is there any way I can import EEG data pre-processed in Brain Vision Analyzer into FieldTrip, so that I don't have to reprocess the data in FieldTrip?

I have some EEG data that I pre-processed (filtered, segmented, ICA etc) in Brain Vision Analyzer and would now like to import them into FieldTrip to use some of the connectivity functions. Is there any way I can do this? Or do I have to start from the beginning in FieldTrip and re-process all of the data? I couldn't find a way of doing this on the FieldTrip website so any advice would be much appreciated.

Most recent answer

Hello Dr. Shephard,
I am having the same question as you had three years ago - I use the generic data export function in BVA2 to export averaged data for each subject, and I could not find a way to make Fieldtrip read the exported data properly. I tried to use ft_definetrial but it keeps warning me that the resolution is unknown for the recording units. Have you encountered the same situation before? Thank you very much.

Popular answers (1)

Javier J. Gonzalez-Rosa
Universidad de Cádiz
Dear Elizabeth,
You have different ways to export your (Analyzer) pre-processed data into FiledTrip by:
Option 1. Export > EDF. This option converts your current analyzer files  into a .edf file.
Option 2. Export > Generic data.
Option 3. Transformations  > Others > Matlab > Export data in EEGlab format. 
I really prefer the 1 and 3 options because once you have your data in an eeglab format (.set), you can do a lot of analysis with them and export them into matlab, fiedltrip as they share several functionality.
Best,
Javier
4 Recommendations

All Answers (9)

Javier J. Gonzalez-Rosa
Universidad de Cádiz
Dear Elizabeth,
You have different ways to export your (Analyzer) pre-processed data into FiledTrip by:
Option 1. Export > EDF. This option converts your current analyzer files  into a .edf file.
Option 2. Export > Generic data.
Option 3. Transformations  > Others > Matlab > Export data in EEGlab format. 
I really prefer the 1 and 3 options because once you have your data in an eeglab format (.set), you can do a lot of analysis with them and export them into matlab, fiedltrip as they share several functionality.
Best,
Javier
4 Recommendations
Elizabeth Shephard
King's College London
Dear Filipa and Javier
Thank you for your very helpful answers. I hadn't explored the generic data export function in BVA properly, so it's great to know I can do this. 
Many thanks
Lizzie
1 Recommendation
Domenica Veniero
University of Nottingham
Dear Elizabeth, I usually go from preprocessed data in BV to fieldtrip without using EEG lab.
I export my BV epochs with GenericData Export as a .eeg, together with a new header and marker file. Now in Fieldtrip just use  the function ft_definetrial as usual, but add cfg.headerfile which is your BV file. 
Hope this is useful.
Mimma
1 Recommendation
Elizabeth Shephard
King's College London
Hi Mimma
Thank you - that is really helpful! 
Best wishes
Lizzie
Anat Perry
University of California, Berkeley
Hi Elizabeth, 
Did one of the options above work for you? I've been trying to export preprocessed and segmented data from BV to FieldTrip but none of these work for me. Can I ask what you ended up doing?
Thanks,
Anat.  
1 Recommendation
Beatriz Dionisio
Technical University of Munich
Hi Javier! 
I am trying the third option you mentioned through EEGLab, with the events already segmented. I create a new fieldtrip data structure, but the ft functions still miss the cfg.headerfile and cfg.datafile, do you know can I solve this problem?
Thank you!
Beatriz.
Elizabeth Shephard
King's College London
Anat, sorry for the very slow reply! I assume you have an answer now but just in case not, I export the data from BVA using generic data export, and then read the .eeg file into FieldTrip.
2 Recommendations
Hello Dr. Shephard,
I am having the same question as you had three years ago - I use the generic data export function in BVA2 to export averaged data for each subject, and I could not find a way to make Fieldtrip read the exported data properly. I tried to use ft_definetrial but it keeps warning me that the resolution is unknown for the recording units. Have you encountered the same situation before? Thank you very much.

Similar questions and discussions

Converting from partial eta^2 to cohen's d for repeated measures (within-subject) designs?
Question
7 answers
  • Caitlin DuncanCaitlin Duncan
Dear all,
Is there a way to convert partial eta^2 to cohen's d for repeated measures designs? I ask because I am conducting a meta-analysis and need to convert the studies' results into a common effect size.
I read that it can be calculated in 2 steps: first cohen's f and then cohen's d.
(1) cohen's f can be calculated from partial eta^2 as follows:
cohen's f = sqrt(partialeta^2/1-partialeta^2)
(2) cohen's f can be converted to cohen's d as follows:
cohen's d = f*2
When I try this with an example from a paper in which there was a partial eta^2 of .42, I get the following:
f=.85
d=1.7
However, I also have the pre and post means and SDs, and when I calculate the cohen's drm according to Lakens (2013), I get very different values. (Note that I do not have the r-value so I will assume one of .5). Mpre = .92, SDpre = .09, Mpost = .98, SDpost = .02.
Cohen's drm = (Mdiff/sqrt(SDpre^2 + SDpost^2 - 2 * r * SDpre * SDpost)) * sqrt(2(1-r))
drm = .73.
This is a huge difference. Even when changing the r-values, this effect size does not get close to the d-value of 1.7 estimated from the partial eta^2 value.
As such, I presume that the calculation I used from partial eta^2 to cohen's d is incorrect for a repeated measures design, and that a correction needs to be applied at step 1 or 2 (or both). I have not been able to find information about this so far. Does anyone know how to do this conversion for repeated measures designs properly?
Thank you in advance for your help.

Related Publications

Code
Script that allows time-domain EEG data exported from Brain Vision Analyzer to be read by Fieldtrip. Data can be segmented or averaged, with as much preprocessing done as you'd like.
Chapter
This is a commentary to the case narrative, “Problem Amongst the Planets” written by Thomas Gaudin.
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