to be highly advantageous in studies of this nature. cerebral oximetry nirs monitoring is helpful in a number of ways. preterm infants can be monitored reducing cerebral hypoxia and hyperoxia with different patterns of activities. it is an effective aid in cardiopulmonary bypass, is strongly considered to improve patient outcomes and reduce costs and extended stays. there are inconclusive results for use of nirs with patients with traumatic brain injury, so it has been concluded that it should remain a research tool. diffuse optical tomography diffuse optical tomography is the 3d version of diffuse optical imaging. diffuse optical images are obtained using nirs or fluorescence-based methods. these images can be used to develop a 3d volumetric model which is known as the diffuse optical tomography.10-20 system fnirs cap fnirs electrode locations can be defined using a variety of layouts, including names and locations that are specified by the international 10–20 system as well as other layouts that are specifically optimized to maintain a consistent 30mm distance between each location. in addition to the standard positions of electrodes, short separation channels can be added. short separation channels allow the measurement of scalp signals. since the short separation channels measure the signal coming from the scalp, they allow the removal of the signal of superficial layers. this leaves behind the actual brain response. short separation channel detectors are usually placed 8mm away from a source. they do not need to be in a specific direction or in the same direction as a detector. functional neuroimaging the use of fnirs as a functional neuroimaging method relies on the principle of neuro-vascular coupling also known as the haemodynamic response or blood-oxygen-level dependent (bold) response. this principle also forms the core of fmri techniques. through neuro-vascular coupling, neuronal activity is linked to related changes in localized cerebral blood flow. fnirs and fmri are sensitive to similar physiologic changes and are often comparative methods. studies relating fmri and fnirs show highly correlated results in cognitive tasks. fnirs has several advantages in cost and portability over fmri, but cannot be used to measure cortical activity more than 4 cm deep due to limitations in light emitter power and has more limited spatial resolution. fnirs includes the use of diffuse optical tomography (dot/nirdot) for functional purposes. multiplexing fnirs channels can allow 2d topographic functional maps of brain activity (e.g. with hitachi etg-4000, artinis oxymon, nirx nirscout, etc.) while using multiple emitter spacings may be used to build 3d tomographic maps. hyperscanning hyperscanning involves two or more brains monitored simultaneously to investigate interpersonal (across-brains) neural correlates in various social situations, which proves fnirs to be a suitable modality for investigating live brain-to-brain social interactions. virtual and augmented reality modern fnirs systems are combined with virtual or augmented reality in studies on brain-computer interfaces, neurorehabilitation or social perception. mobile and wireless fnirs and eeg systems synchronized with all-in-one head mounted display (photoncap, cortivision) music and the brain fnirs can be used to monitor musicians' brain activity while playing musical instruments. advantages and disadvantages the advantages of fnirs are, among other things: noninvasiveness, low-cost modalities, perfect safety, high temporal resolution, compatibility with other imaging modalities, and multiple hemodynamic biomarkers. however, no system is without limitations. for fnirs those include: low brain sensitivity, low spatial resolution, and shallow penetration depth. future directions despite a few limitations, fnirs devices are relatively small, lightweight, portable and wearable. due to these features, applications for the devices are astounding—which make them easily accessible in many different scenarios. for example, they have the potential to be used in clinics, global health, a natural environment, and as a health tracker. ultimately, future at-risk individuals in hospitals could benefit from neuromonitoring and neurorehabilitation that fnirs can offer. now there are fully wireless research grade fnirs systems in the market. fnirs compared with other neuroimaging techniques when comparing and contrasting neuroimaging devices it is important to look at the temporal resolution, spatial resolution, and the degree of immobility. in particular, eeg (electroencephalograph) and meg (magnetoencephalography) have high temporal resolution, but a low spatial resolution. eeg also has a higher degree of mobility than meg has. when looking at fnirs, they are similar to an eeg. they have a high degree of mobility as well as temporal resolution, and they have low spatial resolution. pet scans and fmris are grouped together, however they are distinctly different from the other neuroimaging scans. they have a high degree of immobility, medium/high spatial resolution, and a low temporal resolution. all of these neuroimaging scans have important characteristics and are valuable, however they have distinct characteristics. among all other facts, what makes fnirs a special point of interest is that it is compatible with some of these modalities, including: mri, eeg, and meg.