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. 2025 Apr;12(2):027801.
doi: 10.1117/1.NPh.12.2.027801. Epub 2025 Apr 18.

The fNIRS glossary project: a consensus-based resource for functional near-infrared spectroscopy terminology

Katharina Stute  1 Louisa K Gossé  2 Samuel Montero-Hernandez  3   4 Guy A Perkins  3   5 Meryem A Yücel  4 Simone Cutini  5 Turgut Durduran  6   7 Ann-Christine Ehlis  8 Marco Ferrari  9 Judit Gervain  5   10 Rickson C Mesquita  3   11 Felipe Orihuela-Espina  3 Valentina Quaresima  9 Felix Scholkmann  12   13 Ilias Tachtsidis  14 Alessandro Torricelli  15   16 Heidrun Wabnitz  17 Arjun G Yodh  18 Stefan A Carp  19 Hamid Dehghani  3 Qianqian Fang  20 Sergio Fantini  21 Yoko Hoshi  22 Haijing Niu  23 Hellmuth Obrig  24   25 Franziska Klein  26   27 Christina Artemenko  28 Aahana Bajracharya  29   30 Beatrix Barth  8   31   32 Christian Bartkowski  33   34 Lénac Borot  35 Chiara Bulgarelli  2 David R Busch  36 Malgorzata Chojak  37 Jason M DeFreitas  38 Laura Diprossimo  39 Thomas Dresler  8   31   32 Aykut Eken  40 Mahmoud M Elsherif  41 Lauren L Emberson  42 Anna Exner  43 Talukdar Raian Ferdous  44 Abigail Fiske  45 Samuel H Forbes  46 Jessica Gemignani  5   47 Christian Gerloff  48   49   50 Ségolène M R Guérin  51 Edgar Guevara  52 Antonia F de C Hamilton  53 S M Hadi Hosseini  54 Divya Jain  55 Anastasia N Kerr-German  56 Haiyan Kong  57 Agnes Kroczek  8 Jason K Longhurst  58 Michael Lührs  59   60 Rob J MacLennan  61   62 David M A Mehler  27   63   64 Kimberly L Meidenbauer  65 David Moreau  66   67 Murat C Mutlu  68   69 Renato Orti  70 Ishara Paranawithana  71   72 Paola Pinti  2 Ali Rahimpour Jounghani  54 Vanessa Reindl  49   73 Nicholas A Ross  74 Sara Sanchez-Alonso  75 Oliver Seidel-Marzi  76 Mohinish Shukla  5   77 Syed A Usama  78   79 Musa Talati  14 Grégoire Vergotte  80 M Atif Yaqub  6 Chia-Chuan Yu  81   82 Hanieh Zainodini  83
Affiliations

The fNIRS glossary project: a consensus-based resource for functional near-infrared spectroscopy terminology

Katharina Stute et al. Neurophotonics. 2025 Apr.

Abstract

Significance: A shared understanding of terminology is essential for clear scientific communication and minimizing misconceptions. This is particularly challenging in rapidly expanding, interdisciplinary domains that utilize functional near-infrared spectroscopy (fNIRS), where researchers come from diverse backgrounds and apply their expertise in fields such as engineering, neuroscience, and psychology.

Aim: The fNIRS Glossary Project was established to develop a community-sourced glossary covering key fNIRS terms, including those related to the continuous-wave (CW), frequency-domain (FD), and time-domain (TD) NIRS techniques.

Approach: The glossary was collaboratively developed by a diverse group of 76 fNIRS researchers, representing a wide range of career stages (from PhD students to experts) and disciplines. This collaborative process, structured across five phases, ensured the glossary's depth and comprehensiveness.

Results: The glossary features over 300 terms categorized into six key domains: analysis, experimental design, hardware, neuroscience, mathematics, and physics. It also includes abbreviations, symbols, synonyms, references, alternative definitions, and figures where relevant.

Conclusions: The fNIRS glossary provides a community-sourced resource that facilitates education and effective scientific communication within the fNIRS community and related fields. By lowering barriers to learning and engaging with fNIRS, the glossary is poised to benefit a broad spectrum of researchers, including those with limited access to educational resources.

Keywords: continuous-wave near-infrared spectroscopy; diffuse correlation spectroscopy; frequency-domain near-infrared spectroscopy; functional near-infrared spectroscopy; glossary; time-domain near-infrared spectroscopy.

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Figures

Fig. 1
Fig. 1
Timeline and milestones of the project.
Fig. 2
Fig. 2
Example of a term entry in the fNIRS Glossary Project online version, displaying all available fields.
Fig. 3
Fig. 3
Graphical representation of a block design illustrating task and rest periods, with key terms such as stimulus onset asynchrony (SOA), interstimulus interval (ISI), and the convoluted hemodynamic response function (HRF).
Fig. 4
Fig. 4
Graphical representation of a typical fNIRS measurement setup, highlighting key terms such as the source and detector, which form a channel, as well as short- and long-separation channels, among others.
Fig. 5
Fig. 5
Different common types of motion artifacts in fNIRS research.

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