Functional near infrared spectroscopy (NIRS) is a technique that allows you to monitor the activity of selected areas of the brain by measuring the level of oxygen in the blood flowing through those areas. The measurement is carried out with the use of small infrared light sources (LEDs) that emit waves of various lengths towards our brain. Light waves penetrating the tissues are partially absorbed and dispersed, which depends on the amount of oxygen in the blood particles (hemoglobin) flowing through the examined area. By measuring the difference in the parameters of the light sent to the brain and the light that returns to the detectors after it passes through the tissue, we are able to determine the concentration changes:
- oxygenated hemoglobin (HbO2)
- deoxygenated hemoglobin (Hb)
- total concentration of hemoglogin (HbT)
Changes in the concentration of these three parameters allow us to conclude about the oxygen demand of a given area of the brain, and therefore about its activity at the time of measurement. We can observe the light penetrating the tissues of our body at any time by placing our hand against the background of the sun or a lamp. The infrared light used in fNIRS penetrates our skull and brain in a similar way.
Near-infrared spectroscopy is one of the youngest brain imaging techniques and, unlike other methods, it is:
FNIRS is a safe method of examining the work of the brain. No negative impact of this technology on humans has been found.
It is painless and completely safe. The tissues of the examined person are not damaged during registration. So far, no negative impact of the use of near infrared spectroscopy on the human body has been found.
NIRS technology is energy-efficient and does not require the use of disposable, consumable accessories such as gels, disposable electrodes or conductive liquids.
This technology is much less susceptible to electromagnetic interference from the environment than, for example, EEG devices.
NIRS may be considered the most convenient technology for studying brain activity as it leaves a lot of flexibility to the user and allows for mobility and self-service.
NIRS allows for integration with other research and computer devices such as VR goggles, eye trackers or EEG.
Thanks to these advantages, it is possible to use fNIRS in „non-laboratory” conditions, on the move and without constant supervision by the researcher.