Are event files required for MEG data?

[monique2208]

We recently found when running the bids validator that there are no warnings for missing event files with MEG data (when the task is not rest). Going over the specification it is not entirely clear to me whether they are required like they are for task fMRI. On MRI it says the following: "For task based fMRI, a corresponding task events file (see below) MUST be provided (please note that this file is not necessary for resting state scans)." But similar language is not used on the pages describing MEG or EEG data. So I am not sure if that is the case or if this is an issue in the validator.

I cannot currently share the data we validated, but I found a case on OpenNeuro where there is also no warning although the task is not rest and there are no event files: https://openneuro.org/datasets/ds004738/versions/1.0.1

[Remi-Gau]

which version of the validator are you using?

I modified this example by removing the events.tsv: https://github.com/bids-standard/bids-examples/tree/master/ds000248

ds000248/sub-01
├── anat
│   ├── sub-01_FLASH.json
│   ├── sub-01_FLASH.nii.gz
│   ├── sub-01_T1w.json
│   ├── sub-01_T1w.nii.gz
│   └── sub-01_THISSUFFIXISNOTVALID.json
├── meg
│   ├── sub-01_acq-calibration_meg.dat
│   ├── sub-01_acq-crosstalk_meg.fif
│   ├── sub-01_coordsystem.json
│   ├── sub-01_task-audiovisual_run-01_channels.tsv
│   ├── sub-01_task-audiovisual_run-01_meg.fif
│   └── sub-01_task-audiovisual_run-01_meg.json
└── sub-01_scans.tsv

Using a fairly recent version of the validator

bids-validator --version      
*bids-validator v1.14.7-dev.0-249-g93ca7a02

I get (amongst other things) this:

        [WARNING] Task scans should have a corresponding 'events.tsv' file.
If this is a resting state scan you can ignore this warning or rename the task to include the word "rest".
 (EVENTS_TSV_MISSING)

                ./sub-emptyroom/ses-19210819/meg/sub-emptyroom_ses-19210819_task-noise_meg.fif
                        Evidence: schema.rules.rules.checks.events.EventsMissing
                ./sub-emptyroom/ses-19210819/meg/sub-emptyroom_ses-19210819_task-noise_channels.tsv
                        Evidence: schema.rules.rules.checks.events.EventsMissing
                ./sub-01/meg/sub-01_task-audiovisual_run-01_meg.fif
                        Evidence: schema.rules.rules.checks.events.EventsMissing

                4 more files with the same issue

        Please visit https://neurostars.org/search?q=EVENTS_TSV_MISSING for existing conversations about this issue.

[Remi-Gau]

online validator gives this:

[monique2208]

Thank you for looking into it, in that case we will investigate a bit more. We were using 1.14.8, I will try with a different validator and let you know what happens.

[Remi-Gau]

oh wait, I was unclear: I was using the validator based on deno that uses the BIDS schema.

So install deno: https://docs.deno.com/runtime/fundamentals/installation/
And then install the validator:

deno install -Agf https://github.com/bids-standard/bids-validator/raw/deno-build/bids-validator.js

[effigies]

I would recommend using the distributed version, not the javascript build:

deno run -A jsr:@bids/validator $DATASET

This should line up with what's on the website. @Remi-Gau's command will get you the version based on the latest master branch, which might have some changes.

If you want an install:

deno install -Agf -n bids-validator jsr:@bids/validator

[monique2208]

This works, is this the validator you recommend now, or will the old one still be updated?

[effigies]

The old one will be entirely phased out and we will stop updating it. We may be able to package the new one so that people installing through npm can get an identical experience, but I'm not sure about that.

We're planning to write a blog post to help people understand and navigate the transition soon.