fNIR

fNIR (functional near-infrared) imaging is a spectroscopic method for measuring the level of neuronal activity in the brain. The method is based on neuro-vascular coupling, that is, the relationship between metabolic activity and oxygen level (oxygenated hemoglobin) in feeding blood vessels.

There are three types of fNIR:

• CW - continuous wave - In this method, infrared light shines at the same intensity level during the measurement period. The detected signal is lower intensity static signal (dc-valued)

• FD - frequency domain - In this method, the input signal is a modulated sinusoid at some frequency and the detected output signal has changes in amplitude and phase that correspond to brain activity.

• TR - time-resolved - In time-resolved spectroscopy, a very short IR pulse is introduced, with a pulse length usually on the order of picoseconds. The detected signal is usually a longer signal and has a decay time.

fNIR was first invented by Dr. Britton Chance of the University of Pennsylvania. Current cwFNIR devices have improved with the advent of electronics.[1] At the Optical Brain Imaging Lab of Drexel University, in collaboration with the University of Pennsylvania, battery-operated, wireless cwfNIR devices have been developed.[2]

External links

• Lab of BC at University of Pennsylvania
• Optical Brain Imaging Lab at Drexel University
• Functional Near-Infrared Spectroscopy (fNIRS)

See also

• Near infrared spectroscopy
• Optical imaging