Systemic low frequency oscillations

Definition: Oscillations in fNIRS signals in the frequency range below the heart rate frequency (< ~ 1 Hz). They can be spontaneous and induced by the experimental paradigm. Their sources are multifaceted and include changes in blood volume, hemoglobin oxygenation and the vasculature itself. Physiological processes underlying these effects are for example changes in blood pressure, concentration of CO2 in the blood and activity changes of the autonomic nervous system. A particular oscillation in this frequency range is the Mayer wave oscillation at about 0.1 Hz. SLFOs are always present in fNIRS and fMRI recordings and need to be properly addressed in data analysis. In addition, SLFOs can be also analyzed to gain valuable physiological information.

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References:

https://doi.org/10.1016/j.neuroimage.2003.11.025 https://doi.org/10.1016/j.neuroimage.2013.04.107 https://doi.org/10.1117/1.JBO.21.10.101410

https://doi.org/10.1038/srep17471

https://doi.org/10.1006/nimg.2000.0657

https://doi.org/10.3389/fnhum.2015.00285;

https://doi.org/10.3389/fnhum.2018.00505

https://doi.org/10.3389/fnins.2016.00313;

https://doi.org/10.3389/fnins.2019.00433;

https://doi.org/10.1177/0271678X17753329

Related terms: Physiological Noise, Systemic Activity, Preprocessing, Artifact Correction, Mayer wave, Blood pressure, Respiration