Pre-processed functional data in gifti files: "...func.gii" vs "...bold.func.gii"

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Hi fmriprep experts,

Quick question about the outputs of fmirprep:

What is the difference between files that end in “func.gii” vs. “bold.func.gi” ?

For instance, I have these two files:
sub-002_ses-1_task-fLoc_run-1_space-fsnative_hemi-R.func.gii
sub-002_ses-1_task-fLoc_run-1_space-fsnative_hemi-R.bold.func.gii

The data inside those files are very similar, but not equal.

After running fmriprep on another dataset I only got the bold.func.gii files.

thanks a million!
Alex

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It’s likely that you had previously run with an older version of fMRIPrep. At one point .func.gii was considered sufficient to indicate BOLD data, but this was determined to be out of line with BIDS principles, and we re-added _bold.func.gii, treating .func.gii as an extension like .nii.gz.

The differences will be from some nondeterminism in a registration or distortion correction portion of the pipeline.

I would suggest deleting your *_hemi-?.func.gii files, as they will be less consistent with the rest of your derivatives. If you still have the working directory (passed with -w to fMRIPrep), I might suggest deleting all derivatives and re-running. This will ensure that no other minor renames pollute your outputs. Or just check the mtimes on all your derivatives.