BIDS indicate where and how to save a single event file (_events.tsv) containing information about all tasks events of all conditions. However, such a table is not in in FSL’s ev format, which demands a seperate ev file for each condition of the task.
Where in BIDS are those files need to be saved? I could not find any example or indication for their location on the BIDS site, nor on any of the openNeuro datasets (which has only the raw or fmriprep preprocessed data, not yet processed).
I don’t think you will be able to do what you want to do. Single task event EV files are not BIDS compliant. If you are looking to run a GLM, FitLins is a BIDS app designed to work with fmriprep outputs and BIDS events files.
In addition to @Steven 's response, if you already have events.tsv files and are looking to convert them to FSL FEAT’s custom 3 format, this is actually relatively easy. The reason is that the two required fields in events.tsv files are “onset” and “duration”, which are the 1st and 2nd columns in FSL FEAT’s custom 3 format files. The 3rd column in those custom 3 files is a parametric modulation value (typically just 1). So to create the FSL file from your events.tsv file, simply extract the “onset” and "duration columns from your events.tsv and concatenate a dataframe of a simple column of 1’s (must be the same length as the “onset” and “duration” columns).
Once finished, you can then pass it into FSL FEAT’s Stat tab.
Thanks @dlevitas and @Steven for the answers!
I don’t have a unified events file, and was wondering whether to make one. I realize now this is the BIDS’ way of saving events data.
But to my main point, I was just wondering what is the BIDS way of storing (after creating them) the 3 column events files (seperately for each condition, as opposed to one events file) which is necessary for FSL GLM, which is the most common fMRI analysis as far as I know.
So I understand that BIDS do not indicate where such files supposed to be saved?
Going through FitLins explanation, I do not understand exactly how this solves the issue? Will running FitLins on my dataset recognize those files wherever I put them and will store them in correspondence with BIDS?
I see the FitLins refers to creation of json files containing information about the statistical models, but I don’t see any references to task event files.
You can store them in your derivatives folder somewhere, it’s meant for post-processing/analysis. I typically store my FSL FEAT 3 custom timing file formats like this: derivatives/Analysis/FSL/FEAT_timing_files
I haven’t used FitLins (yet), so I can’t say much about this, but it’s designed to work with fmriprep-processed data, so I imagine it takes the events.tsv at some stage.
FitLins is software that leverages the standardization of BIDS to run GLM analyses. So, you never have to specify an events file, because the software knows already where to look for them, since BIDS is standardized.