By Luca Pollonini and Robert Luke
All members of the fNIRS community are invited to participate in an effort to formally extend the BIDS specification to include fNIRS data.
BIDS (Brain Imaging Data Structure) is a rapidly-expanding, community-driven standard that specifies how to organize neuroimaging and behavioral data with the goal of improving ease of use, accessibility and reproducibility of neuroimaging data and analytical methods. Based on widespread file formats and a hierarchical folder structure, BIDS covers most common neuroimaging experiments, including but not limited to (f)MRI, (i)EEG, MEG and ASL, but at the same time is intuitive and easy to adopt. A large ecosystem of tools and resources and data repositories are already BIDS-compatible, hence this is the perfect time to add fNIRS to this useful platform.
At this time, a BIDS Extension Proposal for fNIRS is publicly available for everyone to review and comment on. The logical choice is to adopt SNIRF as the official file format for fNIRS data, but there are several fNIRS-specific areas of the BIDS specification that are yet to be consensually agreed upon, hence your input is much welcome.
Specifically, it is important to ensure that time-domain and frequency-domain information are adequately included or, at least, that nothing precludes from adding them in the future in a backward-compatible manner. Also, attention is being devoted to properly represent hyperscanning (a discussion of a technique agnostic proposal on how to store hyperscanning is ongoing) and whether or not to explicitly identify short-separation channels (i.e., SNIRF does not do that, leaving users the option to automatically determine them based on distance or to manually flag them). To promote an open and community-driven discussion we encourage you to make comments and edits directly in the document linked above and share your experience or opinion in any of the open discussions.