Continuous Wave fNIR imaging offers the researchers with a portable functional near-infrared (fNIR) imaging research tool capable of monitoring brain’s hemodynamics and thereby the cognitive state of the subject in natural environments. fNIR technology employs specific wavelengths in an optical frequency window which can easily pass through a few centimeters for most tissue, and allow monitoring blood oxygenation changes but monitoring back-scattered light intensity. The relative changes of light intesity across time is due to changes in oxy- and deoxy-hemoglobin and provides information about neural activity.
- Techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have been widely used for functional brain studies in humans.
- These techniques are expensive, highly sensitive to motion artifacts, confine the participants to restricted positions, and may expose individuals to potentially harmful materials (PET) or loud noises (fMRI).
- These characteristics make these imaging modalities unsuitable for many uses, including the monitoring of ongoing cognitive activity under routine working conditions.
- fNIR is the only stand-alone and field-deployable technology able to determine localized brain activity.
- fNIR can be readily integrated with other physiological and neurobehavioral measures that assess human brain activity, including eye tracking, pupil reflex, respiration and electrodermal activity. fNIR can also complement other techniques.
- Studies have shown a positive correlation between a participant’s performance and fNIR responses as a function of task load.
- It has also been shown that fNIR can effectively monitor attention and working memory in real-life situations.