Artifact

Definition: In the context of fNIRS, an artifact is a disturbance of the fNIRS signal that makes the identification of physiologically relevant information in the fNIRS signal difficult or impossible. Generally it is a component of the fNIRS signal that is not induced by neuronal activity and may thus contaminate the measured hemodynamic response. Common sources of artifact in fNIRS data include relative movement between the optodes and the scalp (i.e. motion artifacts), optical signal changes caused by non-brain function related physiological variations (e.g., effects of blood flow changes in the scalp or respiration), environmental variations (e.g., due to stray or ambient light), as well as undesired instrument fluctuations (i.e., related to the measurement equipment).

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References:

https://doi.org/10.3389/fnins.2012.00147

https://doi.org/10.1016/j.neuroimage.2013.04.082

Related terms: Physiological Noise, Filtering, Noise, Motion Correction, Accelerometer, Gyroscope, Inertial measurement Unit (IMU), Low-Pass Filter, High-Pass Filter, Band Pass Filter, baseline shift, baseline drift