About this Research Topic
Near-infrared spectroscopy (NIRS) can be used to monitor brain activity by identifying and measuring changes in the concentrations of oxygenated and deoxygenated hemoglobin with diffuse transmittance of NIRS light at an appropriate combination of wavelengths. Multi-channel continuous wave NIRS has been used extensively for functional neuroimaging over the past decade, partly because it is considered a powerful tool for investigating brain function, particularly in cases where other neuroimaging techniques are not suitable. The primary advantage of using NIRS to assess brain activity is that the technique can be performed under less body constraints than other imaging modalities require. For instance, functional magnetic resonance imaging (fMRI) and electrophysiological recording require that the subject maintain an unusual body posture, such as the sphinx position in non-human animals or the supine position in humans while performing cognitive tasks, and head movement must be severely restricted. Moreover, fMRI emits a loud noise that is not only uncomfortable but may interfere with interpretation of the results. In this respect, the conditions for performing NIRS measurements are much more comfortable for human as well as non-human subjects. Therefore, despite the low temporal- and spatial-resolution and limited depth of the recording compared to fMRI and electrophysiological recordings, respectively, NIRS is useful for studying brain activity under more ‘natural’ and therefore much more variable conditions.
Consequently, topics that NIRS studies could address are highly variable, and more diverse than those with other non-invasive imaging research techniques. That fact makes NIRS most suitable for the functional research of prefrontal cortex, which has been undertaken with respect to more broadly based issues across the broad expanse of disciplines. In fact, many academic journals in diverse areas publish findings obtained from pioneering NIRS measurements of brain regions. This diversity of NIRS applications makes difficult to access accumulated experience. Protocols of NIRS recordings from various studies are not yet standardized and not grounded on available knowledge of NIRS use. Researchers interested in NIRS would benefit from an overview about its potential utilities for future research directions.
To resolve these problems, this Research Topic provides a forum for scientists planning functional studies of prefrontal brain activation using NIRS. It addresses multifaceted aspects of applying NIRS to various scientific disciplines such as pediatrics, psychology, psychiatry, neurophysiology, neuroethology. This forum serves as a reference repository of knowledge from these fields as well as a conduit of information from leading researchers before it would be standardized in textbooks. It offers an extensive cross-referencing system that will facilitate search and retrieval of information about NIRS measurements in activation studies. Reviews of current methodological problems of NIRS research and its perspectives, as well as the presentations of ongoing original work are welcomed.
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