Exporting single-trial ERPs pre-processed in ERPlab

Discussions
1

Hi all,

I am new to Brainstorm and wondering whether it is possible to export single-trial ERP data from .set files that have been pre-processed and epoched in ERPlab. I know it’s possible to import these .set files to Brainstorm, but I’d like to extract the single-trial information, maintaining all of the bin information I set up in the ERPlab environment. (Ultimately I would like to extract single-trial peak amplitudes, e.g., for the P1 component, not the entire time-window.) In a recent Brainstorm webinar I was told that the Brainstorm database can’t maintain all of the categories from the ERPlab binlister, but that it might be possible to reconstruct the bin information as folders in Brainstorm, and then export single-trial ERPs with all of the relevant trial/condition information. Does anyone have experience with this? Any help would be much appreciated!

Nicole

2

Hi Nicole,

If you import any .set file into Brainstorm, you would get a window asking you what combination of parameters you want to use to classify them into the Brainstorm database.
For instance, if you have two parameters (Gender and Condition), each of them with different possible values (respectively m/f and A/B/C), you would not be able to keep the two-level classification in Brainstorm. You would have to “flatten” it, deciding if you are interested by one or the other or both conditions.
You could decide to create 2 folders (Gender_m/Gender_f), 3 folders (Condition_A, Condition_B, Condition_C) or 6 folders (Am, Af, Bm, Bf, Cm, Cf).

Then you would be able to manipulate all your trials freely with the database explorer (works more or less like a regular file explorer). This is illustrated in this tutorial:
http://neuroimage.usc.edu/brainstorm/Tutorials/TutRawAvg

If you are planning to use Brainstorm, I would recommend you start by following the 12+3 introduction tutorials, followed by the EEG/Epilepsy tutorial (for some details related with EEG).
http://neuroimage.usc.edu/brainstorm/Tutorials

Cheers,
Francois

3

Hi Francois,

Thanks for your help re: data importing. What I am wondering specifically is whether, once the data are imported and appropriately labeled as per whatever folder structure is best for me, is it then possible to extract the data on a single-trial basis, e.g., single-trial estimates of peak amplitude for all different conditions. The tutorials you have suggested look useful for traditional means of ERP analysis on averaged data, but as far as I can tell, the tutorials group epoching and averaging together as a sort of 2-step process for traditional ERP analyses. I am interested in exporting data after epoching but before averaging. Is this possible to do in Brainstorm?

Thanks,
Nicole

4

Hi Nicole,

You are free to do what you want the files in the database. You have access to the individual trials, you can easily plug in you own analysis pipeline after the pre-processing + importing.
It will become more clear after you follow the tutorials.

Francois