Functional optical brain imaging is more commonly known as a scientific research technique called functional near-infrared spectroscopy (fNIRS). This technique is a type of functional neuroimaging technology that offers a relatively non-invasive, safe, portable, and low-cost method of indirect and direct monitoring of brain activity. By measuring changes in near-infrared light, it allows researchers to monitor blood flow in the front part of the brain. It is still a new technique, so it is not yet widely used in research, but it shows promising results in studies done to-date.

How a fNIRS sensor is worn.

A typical fNIRS sensorMore technically, it allows functional imaging of brain activity (or activation) through monitoring of blood oxygenation and blood volume in the pre-frontal cortex. It does this by measuring changes in the concentration of oxy- and deoxy-haemoglobin (Hb) as well as the changes in the redox state of cytochrome-c-oxidase (Cyt-Ox) by their different specific spectra in the near-infrared range between 700-1000 nm.

The functional near-infrared spectroscopy (fNIRS) sensor is attached to the subject’s forehead and can be monitored either connected directly to a computer, or a portable computing device that records the subject’s data as he or she engages in specific tasks. The data is recorded and then analyzed for changes in the blood flow or its oxygenation levels of the brain before, during, and after the task. Hypotheses can then be tested about how brain activity is being affected by certain tasks or behaviors.

A typical fNIRS sensor


APA Reference
Grohol, J. (2007). What is Functional Near-Infrared Spectroscopy?. Psych Central. Retrieved on November 26, 2014, from
Scientifically Reviewed
    Last reviewed: By John M. Grohol, Psy.D. on 30 Jan 2013
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