Reproducibility of fNIRS within subject for visual and motor tasks

Study Overview: fNIRS Reproducibility in Clinical Applications. Functional Near-Infrared Spectroscopy (fNIRS) has become a highly popular method to non-invasively identify brain activity by assessing changes in oxygenated (HbO) and deoxygenated (HbR) hemoglobin concentrations. Because of its high portability and tolerance for movement, fNIRS is incredibly appealing for real-world neuroscience, hyperscanning, and clinical applications. However, validating the reproducibility of these signals over multiple sessions is a crucial step for advancing its diagnostic and longitudinal potential. A recent study published in NeuroImage sought to determine the reliability of fNIRS across repeated sessions, analyzing how well the signals hold up day after day. Methodology & Setup:. Participants: Four participants completed at least ten separate daily sessions., Tasks: Participants performed structured Motor and Visual tasks., Data Collection: High-density fNIRS signals were measured from 102 channels spanning the entire head. To improve spatial accuracy and source localization, digitized optode positions from each session were utilized alongside anatomy-specific source modeling. Key Findings:. Reproducibility was quantified as the percentage of significant task-related activity occurring across sessions via Region of Interest (ROI) and vertex-wise analyses. While individual differences in reproducibility were present, the study concluded that task-related changes in HbO (oxygenated hemoglobin) were significantly more reproducible over multiple sessions than changes in HbR (p < 0.05). Significance for Real-World Neuroscience:. As research moves "beyond the lab," ensuring data consistency is paramount. These findings reinforce the viability of using fNIRS for longitudinal studies—such as tracking long-term neural changes, cognitive rehabilitation progress, or evaluating social interactions over time using hyperscanning setups. By demonstrating the high reproducibility of HbO signals, researchers can confidently deploy advanced fNIRS montages across multiple recording days.