1. Short-channel regression in functional near-infrared spectroscopy is more effective when considering heterogeneous scalp hemodynamics
- Author
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Martin Wolf, Dominik Wyser, Roger Gassert, Michelle Mattille, Olivier Lambercy, Felix Scholkmann, University of Zurich, and Wyser, Dominik
- Subjects
Paper ,Computer science ,Brain activity and meditation ,Neuroscience ,FNIRS ,brain-computer interface ,Short-channel regression ,Neuroimaging ,Separation (statistics) ,Neuroscience (miscellaneous) ,Hemodynamics ,610 Medicine & health ,general linear model ,01 natural sciences ,010309 optics ,03 medical and health sciences ,0302 clinical medicine ,0103 physical sciences ,medicine ,functional near-infrared spectroscopy ,2741 Radiology, Nuclear Medicine and Imaging ,Radiology, Nuclear Medicine and imaging ,3614 Radiological and Ultrasound Technology ,Brain–computer interface ,General linear model ,Radiological and Ultrasound Technology ,business.industry ,brain–computer interface ,Pattern recognition ,10027 Clinic for Neonatology ,Research Papers ,Regression ,physiological systemic artifacts ,medicine.anatomical_structure ,2801 Neuroscience (miscellaneous) ,Scalp ,scalp hemodynamics ,Functional near-infrared spectroscopy ,Artificial intelligence ,business ,030217 neurology & neurosurgery - Abstract
Significance: The reliability of functional near-infrared spectroscopy (fNIRS) measurements is reduced by systemic physiology. Short-channel regression algorithms aim at removing systemic “noise” by subtracting the signal measured at a short source–detector separation (mainly scalp hemodynamics) from the one of a long separation (brain and scalp hemodynamics). In literature, incongruent approaches on the selection of the optimal regressor signal are reported based on different assumptions on scalp hemodynamics properties. Aim: We investigated the spatial and temporal distribution of scalp hemodynamics over the sensorimotor cortex and evaluated its influence on the effectiveness of short-channel regressions. Approach: We performed hand-grasping and resting-state experiments with five subjects, measuring with 16 optodes over sensorimotor areas, including eight 8-mm channels. We performed detailed correlation analyses of scalp hemodynamics and evaluated 180 hand-grasping and 270 simulated (overlaid on resting-state measurements) trials. Five short-channel regressor combinations were implemented with general linear models. Three were chosen according to literature, and two were proposed based on additional physiological assumptions [considering multiple short channels and their Mayer wave (MW) oscillations]. Results: We found heterogeneous hemodynamics in the scalp, coming on top of a global close-to-homogeneous behavior (correlation 0.69 to 0.92). The results further demonstrate that short-channel regression always improves brain activity estimates but that better results are obtained when heterogeneity is assumed. In particular, we highlight that short-channel regression is more effective when combining multiple scalp regressors and when MWs are additionally included. Conclusion: We shed light on the selection of optimal regressor signals for improving the removal of systemic physiological artifacts in fNIRS. We conclude that short-channel regression is most effective when assuming heterogeneous hemodynamics, in particular when combining spatial- and frequency-specific information. A better understanding of scalp hemodynamics and more effective short-channel regression will promote more accurate assessments of functional brain activity in clinical and research settings., Neurophotonics, 7 (03)
- Published
- 2020