fNIRS & NIRx Brain Recording Technology
Near Infrared Spectroscopy (NIRS), also called functional Near Infrared Spectroscopy (fNIRS), optical recording technology measures changes in the brain’s oxygen absorption based on optical properties of hemoglobin (blood). fNIRS technology is presently growing in use world-wide to assess cortical activity during cognitive tasks in both typical populations (including adults, children, and infants) as well as in persons with atypical cognitive disorders. fNIRS, however, has been used for decades in the physiological study of, for example, the heart, breast tumors, cerebral blood flow in premature infants, and the like.
Using safe non-ionizing wavelengths of light in the near-infrared range (700-1000nm), fNIRS technology ideally lends itself to studies of higher cognition over other brain imaging technologies because it has both good temporal resolution (~5 seconds) and good spatial resolution (~4 cm depth), without the use of, for example, radiation (PET), and without requiring research participants to remain motionless in an enclosed structure (fMRI). With fNIRS, participants’ cortical activity can be assessed while they are comfortably seated in an ordinary chair (adults and children) or even seated in mom’s lap (infants). Notably, fNIRS is the only portable neuroimaging system (the size of a desktop computer), virtually silent, and
can tolerate participants’ subtle movement. This latter feature is particularly outstanding for the neural study of higher cortical functions, such as human language, which necessarily has as one of its key components the movement of the mouth in speech production or the hands in sign language.
fNIRS Makes it Possible to Ask New Questions in Science
fNIRS systems can be used to ask new questions in science never before possible with traditional behavioral and/or brain imaging methods (such as PET, fMRI, ERP, etc.). For example, Petitto and team have used the fNIRS technology to track very specific swatches of neural tissue and neural systems in the infant brain classically associated with language and other higher cognitive processes over time, inclusive of visual and auditory sensory processing. Indeed they have tracked such tissue and systems throughout the course of human development (spanning infants, children, and adults) to identify typical brain development and its associated linguistic and cognitive functions, as well as atypical brain-function development. To be sure, the fNIRS system has made it possible to identify infants who are at risk for language disorders even before their expression of language, and well before the age at which diagnoses of language disorders are clinically available (which, for language, normally does not occur until around age 3 and beyond). In turn, such early identification has benefits for the early remediation of children when neural plasticity is most heightened, and, crucially, it makes possible the design of the most appropriate/targeted therapies.
New Brain Recording Technologies: fNIRS and NIRx Systems
Petitto and team use two related NIR brain recording (brain imaging) technologies. They have one “permanent” fNIRS ETG-4000 brain recording system from Hitachi Japan, and they have three NIRx brain recording systems from NIRx Medical Technologies-Optical Neuroimaging, Berlin, Germany, including one “permanent” system, plus two portable systems. Together, these systems permit first-time study of groups of people outside of the confines of the laboratory, and, crucially, groups of people in social and linguistic interactions. Many contemporary neuroimaging studies in Cognitive Neuroscience and its sister discipline, Educational Neuroscience, are conducted with an individual (studied with a brain recording system) who is engaged in cognitive tasks. However, the addition of multiple systems permits exciting exploration of more naturalistic cognitive processes, for example, those that occur outside in real world contexts, as well as the impact on our
cognitive processes when we humans are interacting in social groups. Each system has powerful strengths and permits among the world’s most sophisticated analyses of neural functions across a wide range of research participants and settings. Of note, the possession of multiple systems affords Petitto and team the ability to meet a fundamental mission of Petitto’s Brain and Language Laboratory for Neuroimaging (BL2): to train and educate large groups of students so as to advance student career choices and the next generation of young scientists. It is the Petitto and team’s goal to make our knowledge and resources available for the greater good of society and for the greater good of the community with which we live; first and foremost, this includes teaching and training students from Gallaudet University and from the PhD in Educational Neuroscience (PEN) program, as well as those interested students and faculty from the Greater Washington DC university communities. Towards this end, the BL2 team offer an intensive fNIRS certification program that trains students in modern neuroimaging experimental design, neural analyses and interpretation, and many other aspects of being a contemporary experimental Cognitive/Educational neuroscientist.